Endocrine

Type 2 diabetes: outpatient pharmacotherapy progression

Clinical Overview and When to Suspect Type 2 Diabetes

— Prevalence rises with age, BMI ≥25 (≥23 in Asian Americans), sedentary lifestyle, and family history in a first-degree relative

— Higher prevalence in Black, Hispanic, Native American, Pacific Islander, and South Asian populations

— History of gestational diabetes, PCOS, prediabetes (A1c 5.7–6.4%), HTN, dyslipidemia, ASCVD, NAFLD, or chronic steroid/antipsychotic use

— Asymptomatic adults meeting USPSTF/ADA screening criteria: age 35–70 with overweight/obesity (USPSTF 2021), or ADA: all adults ≥35, or earlier if risk factors

— Polyuria, polydipsia, blurred vision, fatigue, recurrent candidiasis, slow-healing wounds, acanthosis nigricans

— Incidental hyperglycemia on routine chemistry, or an A1c ordered for unrelated reasons

— T2DM is a longitudinal, ambulatory disease — questions test stepwise drug choice based on A1c trajectory, weight, ASCVD/HF/CKD, hypoglycemia risk, and cost

— Treatment failure with monotherapy is the rule, not the exception — β-cell function declines ~4%/year

— Modern algorithms are comorbidity-driven, not glucose-only

— Glycemic: individualized A1c (typically <7%; <6.5% if young/healthy; 7.5–8% if frail/limited life expectancy)

— Cardiorenal: prevent MI, stroke, HF hospitalization, CKD progression, all-cause mortality

— Weight, BP, lipid, and lifestyle co-management

Board pearl: On Step 3, "newly diagnosed T2DM" stems almost always hide a comorbidity (ASCVD, HFrEF, CKD, obesity) that dictates the first agent — read the vignette for the comorbid clue before picking metformin reflexively.

Definition: Type 2 diabetes mellitus (T2DM) is a progressive disorder of insulin resistance with relative β-cell insufficiency, accounting for ~90–95% of all diabetes in US adults.

Epidemiology and risk factors:

When to suspect in the outpatient clinic:

Why pharmacotherapy progression matters on Step 3:

Goals of therapy frame every drug choice:

Presentation Patterns and Key History

— Routine annual visit; A1c sent per USPSTF in adults 35–70 with overweight/obesity

— Repeat confirmatory testing required on a separate day unless unequivocal hyperglycemia with symptoms

— Polyuria, nocturia, polydipsia, unintentional weight loss, blurred vision (osmotic lens swelling), fatigue

— Genital pruritus, vulvovaginal/balanitis candidiasis, recurrent UTIs

— Non-healing foot ulcer, peripheral neuropathy (stocking distribution paresthesias), erectile dysfunction

— New microalbuminuria on routine UA, unexplained CKD, retinopathy on optometry exam

— Acute MI or stroke uncovering undiagnosed diabetes

— Hyperosmolar hyperglycemic state (HHS): glucose >600, profound dehydration, altered mental status, minimal ketosis — typical of elderly with intercurrent illness

— DKA can occur in T2DM, especially with SGLT2 inhibitor use (euglycemic DKA) or in ketosis-prone diabetes (often African/Caribbean ancestry)

— Duration of hyperglycemia symptoms, weight trajectory (loss vs gain), dietary patterns, physical activity

— Family history of diabetes, premature ASCVD, CKD

— Current medications that worsen glycemia: glucocorticoids, atypical antipsychotics (olanzapine, clozapine), thiazides at high dose, tacrolimus, niacin, β-blockers (mask hypoglycemia)

— Prior gestational diabetes, macrosomic infants, PCOS

— Substance use (alcohol → hypoglycemia risk on sulfonylureas/insulin), occupation (commercial driver — hypoglycemia liability)

Key distinction: T2DM with rapid weight loss, lean body habitus, or DKA at onset should prompt evaluation for LADA (latent autoimmune diabetes in adults) with GAD-65 antibodies — these patients fail oral agents quickly and need insulin.

Asymptomatic screening detection (most common Step 3 presentation):

Classic hyperglycemic symptoms (subacute over weeks–months):

Complication-first presentations (older adults, delayed diagnosis):

Severe hyperglycemic crises (less common in T2DM but tested):

Targeted history must capture:

Physical Exam Findings and Baseline Assessment

— BMI and waist circumference (>40 in men, >35 in women indicates central adiposity)

— BP at every visit; goal <130/80 in most adults with diabetes per ADA/ACC

— Orthostatic vitals if neuropathy or volume depletion suspected (autonomic dysfunction)

— Acanthosis nigricans (velvety hyperpigmentation of neck, axillae) — marker of insulin resistance

— Skin tags, necrobiosis lipoidica (pretibial yellow-brown plaques), diabetic dermopathy (shin spots)

— Eruptive xanthomas if marked hypertriglyceridemia

— Inspection: ulcers, calluses, deformity (Charcot foot — midfoot collapse, "rocker bottom")

— Pulses and ABI if claudication or absent pulses

— 10-g Semmes-Weinstein monofilament at plantar surfaces (loss predicts ulceration)

— 128-Hz vibration sense, ankle reflexes, pinprick

— Euvolemic vs volume-overloaded (HF signs: rales, edema, elevated JVP) → favors SGLT2 inhibitor

— Volume-depleted, frail elderly → caution with SGLT2 (euglycemic DKA, AKI, hypotension)

— Tachycardia at rest may suggest autonomic neuropathy — affects exercise prescription and β-blocker choice

Step 3 management: A documented annual comprehensive foot exam plus dilated eye exam plus urine albumin/creatinine ratio is the trio Step 3 expects at every diabetic patient's care plan — missing them is a common audit/quality-measure question.

Vital signs and anthropometrics:

General and skin findings:

Cardiovascular exam: carotid bruits, peripheral pulses (dorsalis pedis, posterior tibial), capillary refill, JVP, S3/S4

Comprehensive diabetic foot exam (annual minimum, every visit if neuropathy/PAD):

Eye exam referral: dilated funduscopy by optometry/ophthalmology at diagnosis and annually (every 1–2 years if low risk and well controlled)

Oral exam: periodontal disease is more prevalent and worsens glycemic control — refer to dentistry

Baseline hemodynamic and volume status assessment matters before drug selection:

Diagnostic Workup — Initial Labs and Diagnostic Criteria

— Fasting plasma glucose ≥126 mg/dL (fasting ≥8 hours)

— 2-hour plasma glucose ≥200 mg/dL during 75-g OGTT

— A1c ≥6.5% (NGSP-certified, DCCT-aligned assay)

— Random plasma glucose ≥200 mg/dL with classic symptoms or hyperglycemic crisis

— FPG 100–125, 2-hr OGTT 140–199, A1c 5.7–6.4%

— Hemoglobinopathies (HbS, HbC, HbE) — use fasting glucose or fructosamine

— Conditions altering RBC turnover: hemolysis, recent transfusion, EPO use, pregnancy, advanced CKD, iron-deficiency anemia (falsely elevates A1c)

— Use estimated average glucose or CGM-derived metrics in these patients

— CBC, CMP (Cr, eGFR, electrolytes, LFTs)

— Lipid panel (fasting or non-fasting)

— TSH (autoimmune association, especially if T1DM features)

— Urine albumin-to-creatinine ratio (UACR) — single spot urine; ≥30 mg/g = albuminuria

— eGFR — drives metformin/SGLT2 dosing decisions

— Vitamin B12 if on long-term metformin (or at baseline)

— Resting ECG at baseline if symptomatic, ≥40 years, or ASCVD risk factors

— 10-year ASCVD risk calculator drives statin intensity

— Consider coronary artery calcium scoring in selected borderline cases

Board pearl: A single A1c of 6.5% with FPG 110 is not diagnostic — diagnosis requires either two abnormal tests (same or different) or one abnormal test with classic symptoms. Re-test on a separate day before committing the patient to a lifelong diagnosis on the chart.

ADA diagnostic criteria (any one, confirmed on repeat testing unless symptomatic with glucose ≥200):

Prediabetes thresholds (drives intensive lifestyle + consider metformin):

A1c caveats — when A1c is unreliable:

Initial workup panel at diagnosis (all patients):

Cardiovascular risk assessment:

Diagnostic Workup — Advanced and Confirmatory Studies

— GAD-65, IA-2, ZnT8 antibodies — positive in T1DM and LADA; consider if lean, age <50, family hx of autoimmunity, rapid OHA failure

— C-peptide (with concurrent glucose) — low/undetectable in T1DM, preserved or elevated in T2DM/insulin resistance

— Genetic testing for MODY if onset <25, strong autosomal dominant family history, mild non-progressive hyperglycemia, negative antibodies, preserved C-peptide

— Cushing syndrome (central obesity, striae, hypokalemia, easy bruising) → 24-hr urine cortisol, dexamethasone suppression

— Acromegaly (coarse features, enlarging shoe/ring size) → IGF-1

— Hemochromatosis ("bronze diabetes," elevated transferrin saturation, family hx) → ferritin, transferrin sat, HFE genetics

— Chronic pancreatitis or pancreatic cancer (especially new diabetes >age 50 with weight loss) → imaging

— Medication-induced: glucocorticoids, atypical antipsychotics, calcineurin inhibitors, HIV protease inhibitors

— Dilated retinal exam — diabetic retinopathy may be present at T2DM diagnosis (unlike T1DM)

— UACR + eGFR for diabetic kidney disease staging (KDIGO heat map)

— Lipid panel — guide statin

— Liver evaluation: AST/ALT, consider FIB-4 index; refer for elastography if FIB-4 ≥1.3 to assess MASLD/MASH fibrosis

— Sleep study if OSA suspected (snoring, daytime somnolence, HTN)

Key distinction: New-onset diabetes in a thin adult >50 with weight loss and abdominal/back pain warrants pancreatic imaging — diabetes can be the heralding feature of pancreatic adenocarcinoma up to 3 years before diagnosis. Don't reflexively start metformin and move on.

Distinguishing T2DM from other diabetes types (consider if atypical presentation):

Secondary causes of hyperglycemia to exclude when clinically suggested:

Complication-screening studies at or near diagnosis:

Risk Stratification and First-Line Management Logic

— Step 1: Lifestyle modification (5–10% weight loss, Mediterranean/DASH diet, 150 min/week moderate activity, smoking cessation) — universal

— Step 2: Pharmacotherapy initiated at diagnosis in nearly all patients (not lifestyle alone for 3 months as in older paradigms)

— Established ASCVD or high ASCVD risk (≥55 y/o with risk factors): GLP-1 RA with proven CV benefit (semaglutide, liraglutide, dulaglutide) OR SGLT2 inhibitor with proven CV benefit (empagliflozin, canagliflozin) — independent of metformin or A1c

— HFrEF or HFpEF: SGLT2 inhibitor (empagliflozin, dapagliflozin) — class I indication

— CKD with eGFR ≥20 and UACR ≥200 (or eGFR 25–60): SGLT2 inhibitor preferred; GLP-1 RA if SGLT2 contraindicated

— Obesity-dominant phenotype: GLP-1 RA or dual GIP/GLP-1 (tirzepatide) — greatest weight reduction

— Cost or access-limited, no compelling comorbidity: metformin first

— A1c <1.5% above goal: monotherapy

— A1c ≥1.5% above goal: dual therapy from the start

— A1c ≥10%, glucose ≥300, or symptomatic: consider initial insulin (often basal) with plan to de-escalate

Step 3 management: When the vignette gives a comorbidity (HF, ASCVD, CKD, obesity), the comorbidity-targeted agent comes first or alongside metformin — don't waste a step "trialing metformin alone for 3 months" if the patient already has HFrEF. The right answer is empagliflozin now.

2024 ADA Standards of Care framework — choose first agent by dominant clinical driver, not just A1c:

Comorbidity-driven first-line algorithm:

A1c gap from goal guides initial intensity:

Hypoglycemia risk modifiers: prefer agents with low hypoglycemia risk (metformin, GLP-1, SGLT2, DPP-4, pioglitazone) in elderly, CKD, drivers, lone-living patients

Pharmacotherapy — First-Line and Core Agents

— Mechanism: decreases hepatic gluconeogenesis, modestly improves peripheral insulin sensitivity

— Dose: start 500 mg daily/BID with meals, titrate to 1000 mg BID over 4–6 weeks

— A1c reduction: 1–2%; weight neutral or slight loss; no hypoglycemia as monotherapy

— Renal dosing: eGFR ≥45 full dose; 30–44 reduce to 1000 mg/day max and do not initiate; <30 contraindicated

— Hold for IV contrast if eGFR <30 or AKI; resume 48 hr after if renal function stable

— AEs: GI (50% — mitigate with XR formulation, slow titration), B12 deficiency (check annually after 4 yr), rare lactic acidosis

— Mechanism: glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, satiety

— A1c reduction 1–2%; weight loss 4–15 kg (tirzepatide highest)

— CV benefit: semaglutide, liraglutide, dulaglutide

— AEs: nausea (titrate slowly), pancreatitis (rare), gallstones; contraindicated with personal/family hx of medullary thyroid carcinoma or MEN2

— Hold before procedures requiring anesthesia (aspiration risk from delayed gastric emptying — ASA guidance: hold 1 week before surgery for weekly agents)

— Mechanism: block proximal tubule glucose reabsorption → glucosuria, natriuresis

— A1c reduction 0.5–1%; weight loss 2–3 kg; BP reduction 3–5 mmHg

— Benefits: reduce HF hospitalization, slow CKD progression, reduce MACE

— Initiate if eGFR ≥20 (varies by agent); continue until dialysis for cardiorenal benefit

— AEs: genital mycotic infections, UTIs, volume depletion, euglycemic DKA (hold during illness/surgery/fasting — "sick day rule"), Fournier gangrene (rare), increased amputation (canagliflozin signal)

Board pearl: "Sick day" rule for SGLT2 — STOP during acute illness, prolonged fasting, surgery, or low-carb diet to prevent euglycemic DKA. Resume when eating/drinking normally.

Metformin (biguanide) — still the foundational glucose-lowering agent:

GLP-1 receptor agonists (semaglutide, liraglutide, dulaglutide, tirzepatide):

SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin):

Pharmacotherapy — Intensification, Add-Ons, and Insulin

— Add a second agent from a different class targeting residual gap and comorbidities

— Triple therapy is appropriate before insulin in many patients (metformin + GLP-1 + SGLT2 is common modern combination)

— DPP-4 inhibitors (sitagliptin, linagliptin): A1c ↓ 0.5–0.8%, weight neutral, well tolerated; do not combine with GLP-1 (redundant mechanism); avoid saxagliptin/alogliptin in HF (HF hospitalization signal)

— Sulfonylureas (glipizide preferred over glyburide): cheap, effective (A1c ↓1–2%), but hypoglycemia and weight gain; glyburide avoided in elderly/CKD (long-acting metabolites)

— Pioglitazone (TZD): improves insulin sensitivity, helps MASLD; AEs: weight gain, edema, HF exacerbation (contraindicated NYHA III–IV), fracture risk, bladder cancer signal

— Meglitinides (repaglinide): postprandial agent for irregular eaters; CKD-friendly

— Indications: A1c >10%, glucose >300, symptomatic hyperglycemia, catabolism/weight loss, hospitalization, pregnancy, severe hyperglycemia at diagnosis

— Basal insulin first: glargine, detemir, or degludec — start 10 units or 0.1–0.2 U/kg/day at bedtime

— Titrate by 2 units every 3 days based on fasting glucose (goal 80–130); reduce if hypoglycemia

— If basal optimized but A1c still high → add prandial (bolus) insulin at largest meal first (basal-plus), then full basal-bolus, or switch to GLP-1 RA if not already on (often replaces prandial insulin)

— Concentrated insulins (U-300, U-500) for high-dose requirements; insulin pens improve adherence

CCS pearl: When ordering insulin in a CCS case, also order glucose monitoring (fingerstick QID or CGM), hypoglycemia education, glucagon prescription, and follow-up in 1–2 weeks — partial credit hides in the ancillary orders.

Stepwise intensification when A1c remains above goal at 3 months:

Other oral/injectable options and their niches:

Insulin initiation in T2DM:

De-intensification deserves equal attention: in elderly, frail, or polypharmacy patients with A1c well below goal, stop sulfonylurea and basal insulin first to reduce hypoglycemia risk

Special Populations — Elderly and Renal/Hepatic Impairment

— Healthy, few comorbidities, long life expectancy: A1c <7.0–7.5%

— Multiple chronic conditions, moderate cognitive impairment, ADL dependence: A1c <8.0%

— Very complex/poor health, end-stage chronic illness, dementia: A1c <8.5%, avoid hypoglycemia and symptomatic hyperglycemia rather than chase a number

— Prefer agents with low hypoglycemia risk: metformin, DPP-4, GLP-1, SGLT2

— De-prescribe sulfonylureas, glyburide especially, and tight basal-bolus regimens

— Metformin: full dose ≥45, reduced dose 30–44 (do not initiate), avoid <30

— SGLT2: initiate ≥20 (empagliflozin, dapagliflozin); continue for cardiorenal benefit until dialysis

— GLP-1: safe across CKD spectrum including dialysis (semaglutide, dulaglutide, liraglutide); monitor for volume depletion with vomiting

— DPP-4: dose-adjust (sitagliptin, saxagliptin); linagliptin needs no renal adjustment

— Sulfonylureas: avoid glyburide; glipizide preferred but use cautiously

— Insulin: requirements often decrease with worsening eGFR (reduced renal clearance) — risk of hypoglycemia

— Pioglitazone: avoid in HF and advanced CKD due to fluid retention

— Avoid pioglitazone if active liver disease or ALT >2.5× ULN

— Metformin: avoid in decompensated cirrhosis or active alcohol use (lactic acidosis risk)

— GLP-1, SGLT2, DPP-4 generally safe in compensated cirrhosis

— Insulin requires careful titration — gluconeogenesis impaired, hypoglycemia risk

Step 3 management: Frail 82-year-old with A1c 7.8% on metformin + glimepiride and recent fall? Answer: stop glimepiride, accept A1c goal <8%, document shared decision-making. "Add another agent" is wrong.

Older adults (≥65 years) — individualize A1c targets:

CKD — drug-by-drug summary (memorize the eGFR cut-offs):

Hepatic impairment:

Special Populations — Pregnancy, Adolescents, and Pre-Conception

— Optimize A1c to <6.5% before conception to reduce congenital malformation risk (risk rises sharply with A1c >7%)

— Discontinue teratogenic agents: ACEi/ARB, statins, most non-insulin agents except metformin and possibly glyburide

— Folic acid 400–800 mcg daily (some recommend 1 mg in diabetes); higher 4 mg if prior NTD

— Baseline retinal exam (retinopathy can progress in pregnancy); UACR; TSH

— Insulin is the gold-standard pharmacotherapy in pregestational T2DM and in gestational DM not controlled by diet

— Metformin and glyburide cross the placenta; ADA/ACOG: insulin preferred; metformin acceptable if patient declines insulin, but discuss limited long-term offspring data

— GLP-1 RAs, SGLT2 inhibitors, DPP-4, TZDs are contraindicated/avoided in pregnancy

— Glycemic targets: fasting <95, 1-hr postprandial <140, 2-hr <120

— Monitor for preeclampsia, polyhydramnios, macrosomia, fetal growth; serial ultrasounds

— Breastfeeding: metformin and insulin compatible; glyburide acceptable; avoid GLP-1, SGLT2 until lactation complete

— Re-screen women with GDM at 4–12 weeks postpartum with 75-g OGTT, then every 1–3 years lifelong

— First-line: metformin and/or liraglutide (FDA-approved ≥10 years) or empagliflozin (≥10 years); insulin if A1c >8.5% or symptomatic

— More aggressive β-cell decline than adult T2DM — early combination therapy often needed

— Comprehensive comorbidity screening earlier (HTN, lipids, NAFLD, OSA, PCOS, depression)

Key distinction: A woman with T2DM seeking pregnancy needs ACEi and statin stopped, A1c <6.5%, and switch to insulin — this is a guaranteed Step 3 stem. Don't continue empagliflozin "because it's working."

Pre-conception planning in reproductive-age women with T2DM:

During pregnancy:

Postpartum:

Adolescents and young adults with T2DM (rising epidemic):

Complications and Adverse Outcomes

— Diabetic retinopathy: dilated eye exam at diagnosis, then annually (q1–2 yr if low risk); refer to ophthalmology for non-proliferative changes, macular edema, or proliferative disease → anti-VEGF, laser, vitrectomy

— Diabetic kidney disease: annual UACR + eGFR; ACEi or ARB if albuminuria (UACR ≥30) or HTN; add SGLT2 inhibitor if eGFR ≥20 and UACR ≥200; add finerenone (nonsteroidal MRA) if persistent albuminuria on max ACEi/ARB + SGLT2

— Diabetic neuropathy: annual monofilament + vibration + reflexes; for painful neuropathy use duloxetine, pregabalin, gabapentin, or amitriptyline (avoid in elderly); autonomic features → gastroparesis (metoclopramide short term), orthostatic hypotension, neurogenic bladder, ED (PDE5 inhibitors)

— ASCVD: 2–4× higher risk; aggressive statin therapy, BP <130/80, antiplatelet for secondary prevention, GLP-1/SGLT2 with proven CV benefit

— Heart failure: SGLT2 inhibitor regardless of EF

— Stroke, PAD — same prevention principles

— Metformin: B12 deficiency, lactic acidosis (rare, in renal failure/sepsis/contrast), GI intolerance

— SGLT2: euglycemic DKA, mycotic genital infections, volume depletion, Fournier gangrene

— GLP-1: nausea/vomiting (most discontinue for this), pancreatitis, gallbladder disease, ileus signal

— TZD: edema, HF, fractures, bladder cancer (pioglitazone)

— Sulfonylureas: hypoglycemia (especially elderly, CKD, alcohol), weight gain

— Insulin: hypoglycemia, weight gain, injection-site lipohypertrophy

Board pearl: Persistent albuminuria despite ACEi/ARB + SGLT2 at maximal tolerated doses → add finerenone (FIGARO/FIDELIO trials) — Step 3 will test this newer fourth pillar of cardiorenal protection.

Microvascular complications — screen and treat per ADA standards:

Macrovascular complications:

Drug-specific adverse outcomes Step 3 loves to test:

Foot ulceration and amputation: annual comprehensive foot exam + patient education; daily inspection; appropriate footwear; refer to podiatry/wound care early

When to Escalate Care — Hospitalization and Consults

— DKA: glucose >250, anion gap, ketosis, pH <7.3 or HCO3 <18 — ICU/step-down

— HHS: glucose >600, osmolality >320, altered mental status, severe dehydration — ICU

— Severe hyperglycemia with intercurrent illness (infection, MI, stroke) requiring IV fluids/insulin

— Inability to maintain hydration/oral intake at home

— Severe hypoglycemia with persistent altered mental status or recurrent episodes

— A1c >9% despite triple therapy or struggling to reach goal after 6–12 months

— Suspected T1DM, LADA, MODY, or ketosis-prone diabetes

— Insulin pump or CGM initiation candidates needing specialist support

— Pregnancy or pre-conception planning with pregestational diabetes

— Recurrent severe hypoglycemia, hypoglycemia unawareness

— Diabetes complicated by complex comorbidities (steroid-induced, post-transplant)

— Certified diabetes care and education specialist (DCES) at diagnosis, with treatment changes, with complications, and annually

— Registered dietitian for medical nutrition therapy

— Ophthalmology, podiatry, nephrology (eGFR <30 or rapidly declining), cardiology (ASCVD/HF)

— Behavioral health: depression screening (PHQ-9) — comorbid in 25%; diabetes distress screen

— Dentistry; sleep medicine if OSA suspected

— Hold metformin if contrast/major surgery and eGFR concerns

— Hold SGLT2 inhibitor 3–4 days before elective surgery (euglycemic DKA risk)

— Hold GLP-1 RA per anesthesia guidance (aspiration risk)

— Continue basal insulin (usually 80% of dose); hold prandial if NPO; sliding scale plus correction

CCS pearl: For inpatient hyperglycemia, discontinue all oral agents and GLP-1s on admission and use basal-bolus subcutaneous insulin (target 140–180 mg/dL on non-ICU floors). Sliding-scale-only is wrong on CCS.

Inpatient admission criteria for hyperglycemia:

Endocrinology referral indications (outpatient):

Multidisciplinary team referrals (build into every diabetes care plan):

Perioperative escalation:

Key Differentials — Other Forms of Diabetes

— Typically <30 years, lean, rapid symptom onset (days–weeks), DKA at presentation in 30%

— Autoantibody positive (GAD-65, IA-2, ZnT8, insulin), low C-peptide, ketosis-prone

— Requires insulin from diagnosis; oral agents inappropriate

— Phenotype overlap with T2DM: adults >30, often non-obese

— GAD-65 antibodies positive; C-peptide initially preserved but declines faster than T2DM

— Initially controlled on orals but fails within 6 months to a few years → progresses to insulin

— Important to identify because SGLT2 inhibitors carry higher DKA risk in autoimmune diabetes

— Autosomal dominant, often three generations affected, onset <25, mild non-progressive hyperglycemia, antibody-negative, preserved C-peptide

— Subtype-specific therapy: HNF1A/HNF4A MODY responds beautifully to low-dose sulfonylurea (not metformin or insulin); GCK MODY needs no treatment outside pregnancy

— Presents with DKA but later behaves like T2DM; often African or Caribbean ancestry

— May come off insulin after initial DKA resolution

— Pancreatogenic (type 3c): chronic pancreatitis, post-pancreatectomy, pancreatic cancer, CF-related diabetes; brittle glycemic control, fat malabsorption coexists, low C-peptide and low glucagon → unique vulnerability to hypoglycemia

— Endocrinopathies: Cushing, acromegaly, pheochromocytoma, hyperthyroidism, glucagonoma

— Drug-induced: glucocorticoids (most common — postprandial-predominant pattern), atypical antipsychotics, calcineurin inhibitors (post-transplant DM), HIV protease inhibitors, statins (modest risk)

— Hemochromatosis: "bronze diabetes" with cirrhosis, arthropathy, cardiomyopathy

Key distinction: A 19-year-old with diabetes diagnosed at 14, A1c 7.0% on diet alone, mother and grandmother both diagnosed in their 20s, antibodies negative — think MODY, refer for genetic testing; a low-dose sulfonylurea may be ideal.

Type 1 diabetes mellitus:

Latent autoimmune diabetes in adults (LADA):

Maturity-onset diabetes of the young (MODY):

Ketosis-prone diabetes (Flatbush diabetes):

Secondary diabetes:

Key Differentials — Non-Diabetic Hyperglycemia Mimics

— Acute illness (sepsis, MI, stroke, trauma, burns) elevates counter-regulatory hormones

— Patients without prior diabetes may have transient glucose elevations >180–200

— A1c at admission helps distinguish: elevated → undiagnosed diabetes; normal → stress hyperglycemia

— Manage acutely with insulin; re-test glucose and A1c 6–12 weeks post-discharge before assigning diabetes diagnosis

— Especially with morning prednisone — predominant postprandial/afternoon hyperglycemia, often normal fasting

— Manage with NPH timed to prednisone, or short-acting prandial insulin; consider GLP-1 if chronic steroid plan

— Distinct pattern: do not chase fasting numbers; check pre-dinner/bedtime

— Dilute urine, hypernatremia, normal glucose; water deprivation test, copeptin

— Postprandial dips can occur in pre-diabetes

— Psychogenic water intake; normal serum sodium, normal glucose

— Mannitol, post-obstructive diuresis, recovery phase of ATN

— Hematocrit extremes affect glucose meters; high-dose acetaminophen and vitamin C interfere with some CGM sensors

— Confirm with venous lab glucose before committing to a diagnosis or major therapy change

— Hemolytic anemia, recent transfusion, EPO, hemoglobinopathy → false low A1c

— Use fructosamine or CGM-derived mean glucose

Step 3 management: Inpatient with new glucose 240 on day 2 of pneumonia and no prior diabetes — order A1c. If A1c <6.5%, label "stress hyperglycemia," treat with insulin acutely, re-screen at 6–12 weeks post-discharge rather than discharging with a "T2DM" diagnosis.

Stress hyperglycemia:

Steroid-induced hyperglycemia:

Diabetes insipidus (mimics polyuria/polydipsia without hyperglycemia):

Reactive hypoglycemia presenting with hunger/sweating (paradoxically suggests early insulin resistance):

Stress polyuria and primary polydipsia:

Other osmotic diuresis causes:

CGM/glucose meter artifacts:

Hyperglycemia with normal A1c — consider:

Secondary Prevention, Discharge Plans, and Long-Term Strategy

— A1c at goal — individualize target

— BP <130/80 (ACEi/ARB first-line if albuminuria or HTN)

— Cholesterol — statin in nearly all diabetics ≥40 (moderate-intensity primary prevention; high-intensity if ASCVD risk ≥20% or established ASCVD); consider ezetimibe or PCSK9 add-on

— Smoking cessation at every visit

— Aspirin 81 mg for secondary prevention (established ASCVD); primary prevention only in selected high-risk patients with low bleeding risk

— Weight management — 5–10% weight loss target; bariatric surgery referral if BMI ≥35 with comorbidity or ≥30 with uncontrolled diabetes

— Annual influenza

— Pneumococcal: PCV15 followed by PPSV23, or PCV20 alone (per ACIP)

— Hepatitis B series for unvaccinated diabetic adults <60 (and shared decision-making ≥60)

— COVID-19 per current ACIP recs

— RSV in adults ≥60 per shared decision

— Tdap, zoster (≥50), HPV per age

— Medical nutrition therapy: individualized; Mediterranean and DASH have best evidence; carbohydrate counting if on insulin

— Physical activity: 150 min/week moderate aerobic + 2–3 days/week resistance; reduce sedentary time

— Sleep hygiene; OSA treatment improves glycemia

— Glucose monitoring: pre-meal and bedtime if on insulin; CGM increasingly first-line for any insulin user, and now covered for many on basal alone or with high A1c

— Hypoglycemia plan: rule of 15 (15 g carbs, recheck in 15 min); glucagon prescription for any patient on insulin or sulfonylurea

— Sick day rules: continue insulin/most agents, hold SGLT2 and metformin, hydrate, monitor ketones if symptomatic

Board pearl: A diabetic patient with established ASCVD walks out with: high-intensity statin + ACEi/ARB + aspirin + GLP-1 or SGLT2 with proven CV benefit + lifestyle + annual flu/pneumococcal. Missing any one of these on a discharge medication list is a Step 3 trap.

Comprehensive ABCs of T2DM care (every visit checklist):

Vaccinations (don't skip on Step 3):

Lifestyle reinforcement:

Self-management education and tools:

Follow-Up, Monitoring Parameters, and Counseling

— Every 3 months if not at goal or therapy recently changed

— Every 6 months if stable and at goal

— Newly diagnosed or treatment changes: 2–4 week follow-up to assess tolerance and adherence

— Stable patients: every 3–6 months

— Telehealth visits acceptable for stable medication management and education

— Comprehensive foot exam

— Dilated retinal exam (q1–2 yr if low risk)

— UACR + eGFR

— Lipid panel

— Dental exam

— Vaccination review

— Depression and diabetes distress screening

— B12 if on long-term metformin

— Fingerstick: at minimum once daily varied times if on oral agents alone; more frequent if on insulin (pre-meal + bedtime)

— Continuous glucose monitoring (CGM): now recommended for all on multiple daily injections; increasingly covered for basal-only insulin and even non-insulin users with high A1c. Key metrics: time-in-range (70–180 mg/dL) goal >70%, time-below-range <4%, glucose management indicator (GMI)

— Medication adherence review (pill burden, cost barriers, injection technique)

— Symptoms of hypoglycemia and treatment

— Foot care: daily inspection, no barefoot walking, proper nail care, well-fitting shoes

— Driving safety: check glucose before driving on insulin/sulfonylurea; do not drive if <70

— Pregnancy/contraception counseling for reproductive-age women

— Mental health: screen PHQ-9 annually; treat depression aggressively — improves glycemic outcomes

Step 3 management: When the patient returns 3 months later with A1c unchanged on metformin monotherapy, the highest-yield next move is verify adherence, ask about barriers, and intensify — not "wait another 3 months." Therapeutic inertia is a tested concept.

A1c frequency:

Routine outpatient follow-up cadence:

Annual standard-of-care items (Step 3 quality measures):

Self-monitoring:

Counseling at each visit:

Ethical, Legal, and Patient Safety Considerations

— GLP-1 RAs are increasingly prescribed for weight loss off-label; obtain explicit discussion of indication, cost, supply shortages, and discontinuation rebound — document carefully

— SGLT2 inhibitors: discuss euglycemic DKA, mycotic infections, and sick-day rules; document patient understanding

— Insulin initiation: address fears ("insulin failure," needle phobia), demonstrate technique, confirm caregiver involvement if cognitive impairment

— FMCSA requires diabetic CMV drivers on insulin to obtain exemption with quarterly endocrinology evaluation, A1c reporting, and stable hypoglycemia history

— Severe hypoglycemia episode (requiring third-party assistance) typically grounds driving privileges temporarily; states vary in mandatory reporting laws

— Document hypoglycemia discussions in chart

— Beers criteria: avoid glyburide, long-acting sulfonylureas, sliding-scale-only insulin in elderly

— Risk of falls from hypoglycemia → deprescribe sulfonylureas and intensive insulin in frail patients

— Hospital discharge: medication reconciliation must clarify whether home oral agents resume and at what doses; basal insulin doses often need reduction from inpatient levels; ensure follow-up within 1–2 weeks

— Outpatient-to-outpatient transitions (insurance change, new PCP): cost-driven medication changes (e.g., losing GLP-1 coverage) need proactive substitution planning

— Nursing home admission: deprescribe to simplest, lowest-hypoglycemia-risk regimen

— Insulin and GLP-1 affordability remain major adherence barriers; know patient-assistance programs, $35 insulin cap (Medicare), and 340B referrals

— Document attempts at less expensive alternatives when prior authorization is denied

— Diabetic ketoacidosis from intentional insulin omission in a minor may trigger child protective services involvement; in adults with mental illness, involve social work and consider capacity assessment

— HEDIS measure: A1c <8% in the diabetic population; closing care gaps improves both outcomes and reimbursement

Board pearl: A 70-year-old admitted from a nursing home for symptomatic hypoglycemia on glyburide + basal insulin should be discharged on metformin alone (if eGFR allows) or a low-hypoglycemia-risk agent, with A1c goal relaxed to <8%. Continuing the same regimen is a patient-safety wrong answer.

Informed consent and shared decision-making:

Commercial driver and aviation safety:

Polypharmacy and prescribing cascades in elderly:

Transition-of-care risk points (Step 3 favorites):

Health equity and access:

Mandatory reporting:

Quality and value:

High-Yield Associations and Rapid-Fire Clinical Facts

Key distinction: GLP-1 = weight loss + ASCVD; SGLT2 = HF + CKD; combination of both has additive cardiorenal benefit and is the new modern standard in patients with multiple comorbidities.

Empagliflozin, dapagliflozin → HF (any EF) and CKD benefit beyond glycemia; class I for HF

Semaglutide, liraglutide, dulaglutide → ASCVD secondary prevention; semaglutide reduces stroke

Tirzepatide (dual GIP/GLP-1) → greatest A1c reduction (~2%) and weight loss (~20%) among injectables

Metformin + IV iodinated contrast → hold if eGFR <30, AKI, or hepatic dysfunction; resume 48 hr later if renal function stable

Metformin + B12 deficiency → check after 4 years on therapy; check earlier with neuropathy or anemia

SGLT2 inhibitor + acute illness/surgery/fasting/low-carb diet → euglycemic DKA risk; hold during these

Pioglitazone + HF (NYHA III–IV) → contraindicated; also avoid in active bladder cancer

Sulfonylurea + alcohol or skipped meals → hypoglycemia; glyburide especially in elderly/CKD = avoid

DPP-4 (saxagliptin, alogliptin) + HF → increased HF hospitalization signal; prefer sitagliptin/linagliptin

GLP-1 + medullary thyroid carcinoma/MEN2 → contraindicated

GLP-1 + preoperative period → ASA guidance recommends holding weekly GLP-1 1 week pre-op for aspiration risk

Hypoglycemia treatment → conscious: 15 g fast carbs, recheck 15 min (rule of 15); unconscious: IM/intranasal glucagon, then IV dextrose

Glucagon nasal spray → game-changer for caregiver administration; prescribe for all on insulin/SU

Statins in diabetes → moderate intensity for primary prevention age 40–75; high intensity if ASCVD or 10-year risk ≥20%

ACE inhibitor + albuminuria → standard of care even without HTN; can normalize albuminuria

Finerenone → 4th pillar of DKD when ACEi/ARB + SGLT2 maxed and UACR ≥30

A1c 6% but glucose 200 → check for hemoglobinopathy or hemolysis (falsely low A1c)

New T2DM in elderly thin patient + abdominal/back pain → image pancreas

Diagnostic A1c ≥6.5% on two occasions; cutoff 5.7–6.4% = prediabetes

Bariatric surgery → consider at BMI ≥30 with uncontrolled diabetes; remission rates 40–80%

Board Question Stem Patterns

Step 3 management: The single highest-yield approach to these stems: read the comorbidities first, then check the A1c, then choose the agent that treats both. This algorithm wins 80%+ of T2DM pharmacotherapy questions.

Pattern 1 — Comorbidity-driven first agent: "55-year-old man with T2DM (A1c 8.2%), HFrEF (EF 30%), eGFR 55. What is the most appropriate next step?" → empagliflozin (HF + CKD benefit), regardless of metformin status

Pattern 2 — ASCVD plus obesity: "62-year-old woman post-MI, BMI 38, A1c 7.9% on metformin. Best add-on?" → semaglutide (or another GLP-1 with proven CV benefit + weight loss)

Pattern 3 — Frail elderly with hypoglycemia: "84-year-old in assisted living, A1c 6.8% on metformin and glimepiride, two falls in 6 months." → stop glimepiride; goal A1c <8%

Pattern 4 — Pregnancy: "29-year-old with T2DM on metformin and empagliflozin, A1c 6.4%, planning pregnancy." → stop empagliflozin and statin/ACEi, switch to insulin, fortify folate

Pattern 5 — Euglycemic DKA: "Diabetic on empagliflozin presents with nausea, abdominal pain, glucose 180, anion gap 22, ketones positive." → euglycemic DKA; stop SGLT2, IV fluids + insulin + dextrose

Pattern 6 — Lactic acidosis risk: "T2DM on metformin develops sepsis with Cr rising to 2.5 and lactate 5." → discontinue metformin, supportive care

Pattern 7 — LADA: "Lean 35-year-old, A1c 9.5%, fails metformin within 4 months, BMI 22, mother has Hashimoto's." → check GAD-65 antibodies, anticipate insulin

Pattern 8 — Stress hyperglycemia vs new diabetes: "Glucose 240 on day 2 of CAP, A1c 5.6%." → stress hyperglycemia; treat acutely, re-screen 6–12 weeks

Pattern 9 — Statin in diabetes: "45-year-old with T2DM, LDL 110, no ASCVD, 10-yr risk 14%." → moderate-intensity statin

Pattern 10 — Albuminuria management: "T2DM, BP 128/78, UACR 80 mg/g, eGFR 65." → start ACEi or ARB; add SGLT2; statin

Pattern 11 — Perioperative GLP-1: "Patient on weekly semaglutide scheduled for elective cholecystectomy in 5 days." → hold semaglutide 1 week pre-op

Pattern 12 — Cost barrier: "Patient cannot afford GLP-1, has HFrEF and T2DM A1c 8.5%." → SGLT2 inhibitor (generic empagliflozin/dapagliflozin formulations and lower cost than GLP-1, plus HF benefit)

One-Line Recap

Modern outpatient T2DM pharmacotherapy is comorbidity-driven: select agents (GLP-1 RA, SGLT2 inhibitor, metformin) based on the patient's dominant ASCVD, HF, CKD, or obesity phenotype rather than chasing A1c alone, while individualizing glycemic targets, screening complications annually, and aggressively addressing BP, lipids, lifestyle, and vaccinations.

Board pearl: If a Step 3 vignette gives you a comorbidity (HF, ASCVD, CKD, obesity, pregnancy planning), the comorbidity-targeted agent comes first, and a near-perfect approach is GLP-1 + SGLT2 + metformin as your modern triple-pillar foundation in high-risk patients — with adjustments for renal function, pregnancy, and patient safety throughout the longitudinal care journey.

First-line logic: Comorbidity dictates the agent — HFrEF/HFpEF/CKD → SGLT2 inhibitor; ASCVD/obesity → GLP-1 RA; otherwise metformin; combination from the start if A1c ≥1.5% above goal or two comorbidities present.

Goals beyond A1c: Individualize A1c (<7% generally, <8% in complex elderly), but equally treat BP <130/80 with ACEi/ARB, statin in nearly all ≥40, aspirin only for secondary prevention, and 5–10% weight loss.

Safety pillars: Stop SGLT2 during illness/surgery/fasting (euglycemic DKA); hold GLP-1 1 week pre-op; deprescribe sulfonylureas in elderly; verify B12 yearly on chronic metformin; always provide hypoglycemia + glucagon plan for insulin/SU users.

Annual standard-of-care checklist: A1c quarterly until stable; UACR + eGFR; dilated eye exam; comprehensive foot exam; lipid panel; dental visit; depression and diabetes distress screening; influenza, pneumococcal, hepatitis B, COVID-19, RSV (≥60) vaccines; lifestyle reinforcement and diabetes self-management education referral.