A 52-year-old man presents to his primary care physician to discuss laboratory results that were obtained during his annual checkup. He has no symptoms or concerns and denies changes in eating or urination patterns. Specifically, the physician ordered a panel of metabolic laboratory tests to look for signs of diabetes, hyperlipidemia, or other chronic disorders. A spot glucose check from a random blood sample showed a glucose level of 211 mg/dL. A hemoglobin A1c level was obtained at the same time that showed a level of 6.3%. A fasting blood glucose was obtained that showed a blood glucose level of 125 mg/dL. Finally, a 2-hour glucose level was obtained after an oral glucose tolerance test that showed a glucose level of 201 mg/dL. Which of the following statements is most accurate for this patient?

This patient has type 2 diabetes as diagnosed by his oral tolerance blood glucose

This patient does not have type 2 diabetes

This patient has type 2 diabetes as diagnosed by his fasting blood glucose

This patient has type 2 diabetes as diagnosed by his random blood glucose

This patient has type 2 diabetes as diagnosed by his hemoglobin A1c

A 62-year-old man comes to the physician in May for a routine health maintenance examination. He feels well. He underwent a right inguinal hernia repair 6 months ago. He has hypertension and type 2 diabetes mellitus. There is no family history of serious illness. Current medications include metformin, sitagliptin, enalapril, and metoprolol. He received the zoster vaccine 1 year ago. He received the PPSV23 vaccine 4 years ago. His last colonoscopy was 7 years ago and was normal. He smoked a pack of cigarettes a day for 20 years but quit 17 years ago. He drinks two to three alcoholic beverages on weekends. He is allergic to amoxicillin. He is scheduled to visit Australia and New Zealand in 2 weeks to celebrate his 25th wedding anniversary. He appears healthy. Vital signs are within normal limits. An S4 is heard at the apex. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate recommendation at this time?

Pneumococcal conjugate vaccine 13

A 27-year-old Hispanic G2P1 presents for a routine antepartum visit at 26 weeks gestation. She has no complaints. The vital signs are normal, the physical examination is within normal limits, and the gynecologic examination corresponds to 25 weeks gestation. The oral glucose tolerance test (OGTT) with a 75-g glucose load is significant for a glucose level of 177 mg/dL at 1 hour and 167 mg/dL at 2 hour. The fasting blood glucose level is 138 mg/dL (7.7 mmol/L), and the HbA1c is 7%. Which of the following represents the proper initial management?

Dietary and lifestyle modification

A 29-year-old woman presents to the primary care office for a recent history of falls. She has fallen 5 times over the last year. These falls are not associated with any preceding symptoms; she specifically denies dizziness, lightheadedness, or visual changes. However, she has started noticing that both of her legs feel weak. She's also noticed that her carpet feels strange beneath her bare feet. Her mother and grandmother have a history of similar problems. On physical exam, she has notable leg and foot muscular atrophy and 4/5 strength throughout her bilateral lower extremities. Sensation to light touch and pinprick is decreased up to the mid-calf. Ankle jerk reflex is absent bilaterally. Which of the following is the next best diagnostic test for this patient?

Electromyography (including nerve conduction studies)

A 53-year-old woman with type 2 diabetes mellitus is admitted for evaluation of recurrent episodes of nausea, tremors, and excessive sweating. She works as a nurse and reports self-measured blood glucose levels below 50 mg/dL on several occasions. Her family history is positive for borderline personality disorder. The only medication listed in her history is metformin. Which of the following is the most appropriate next step in management?

Ask the patient if she is taking any medications other than metformin

Measure serum C-peptide concentration

Search the patient's belongings for insulin

Measure glycated hemoglobin concentration

Report the patient to her employer

A 59-year-old man presents to his primary care physician complaining of leg pain with exertion for the last 6 months. He has cramping in his calves when walking. He states that the cramping is worse on the right than the left and that the cramping resolves when he stops walking. He has had type 2 diabetes mellitus for 15 years and is not compliant with his medications. He has smoked 20–30 cigarettes daily for the past 30 years. On examination, the femoral pulses are diminished on both sides. Which of the following is the most likely cause of this patient’s condition?

Segmental arterial occlusions due to non-atherosclerotic vasculitis

Diabetes complications and screening for USMLE Step 3: High-Yield Internal Medicine Lessons

Screening & Diagnosis - Catching the Culprit

Screening: Asymptomatic adults aged ≥35. Any age if BMI ≥25 (≥23 in Asians) + ≥1 risk factor (e.g., family hx, HTN, PCOS).
Diagnostic Criteria (confirm with repeat test):
- HbA1c: ≥6.5%
- Fasting Plasma Glucose (FPG): ≥126 mg/dL
- 2-hr Oral Glucose Tolerance Test (OGTT): ≥200 mg/dL
- Random Plasma Glucose: ≥200 mg/dL + symptoms

⭐ HbA1c is unreliable in hemoglobinopathies or conditions with high RBC turnover (e.g., CKD, hemolysis); use FPG or OGTT instead.

FPG thresholds for normal, prediabetes, and diabetes

Microvascular Mayhem - Small Vessels, Big Trouble

Pathophysiology: Chronic hyperglycemia → advanced glycation end-products (AGEs) & polyol pathway activation → basement membrane thickening, endothelial damage, and oxidative stress.
Diabetic Retinopathy
- Non-proliferative: Microaneurysms, dot-blot hemorrhages, hard exudates, cotton-wool spots.
- Proliferative: Neovascularization (VEGF-driven), vitreous hemorrhage, retinal detachment.
- Screening: Annual dilated fundoscopy starting 5 years post-diagnosis for T1DM, and at diagnosis for T2DM.
Diabetic Nephropathy
- Earliest sign: Thickening of the glomerular basement membrane. First clinical sign is microalbuminuria.
- Screening: Annual urine albumin-to-creatinine ratio (UACR). UACR 30-300 mg/g indicates microalbuminuria.
- Pathology: Kimmelstiel-Wilson nodules are pathognomonic.
Diabetic Neuropathy
- Peripheral: Distal, symmetric "stocking-glove" polyneuropathy. Loss of proprioception & vibration.
- Screening: Annual comprehensive foot exam, including 10-g monofilament test.
- Autonomic: Gastroparesis, orthostatic hypotension, erectile dysfunction.

⭐ ACE inhibitors or ARBs are first-line therapy for diabetic nephropathy, providing renal protection independent of their antihypertensive effects.

Diabetic Retinopathy Severity Levels and Hallmarks

Macrovascular Mess - The Highway to Hazard

Atherosclerosis is the primary pathology, accelerated by chronic hyperglycemia, insulin resistance, and dyslipidemia. Leads to major adverse cardiovascular events (MACE).
Coronary Artery Disease (CAD)
- Most common cause of death in diabetics.
- Screen with stress testing if symptomatic or high-risk.
Cerebrovascular Disease (CVD)
- Leads to ↑ risk of stroke and transient ischemic attacks (TIA).
Peripheral Arterial Disease (PVD)
- Presents with claudication, non-healing ulcers, and gangrene.
- Screen with Ankle-Brachial Index (ABI) if symptomatic.

⭐ Due to diabetic autonomic neuropathy, myocardial infarctions can be "silent," presenting with atypical symptoms like shortness of breath, fatigue, or nausea instead of classic chest pain.

Diabetic Foot - An Achilles' Heel

Diabetic foot ulcer with cellulitis

Pathophysiology Triad:
- Neuropathy: ↓ sensation & motor control (📌 SAD: Sensory, Autonomic, Motor).
- Peripheral Artery Disease (PAD): ↓ blood flow, poor healing.
- Immunocompromise: ↑ infection risk.
Screening (Annual):
- Neuropathy: 10-g monofilament test.
- Vascular: Ankle-brachial index (ABI).
Management:
- Glycemic control, patient education, proper footwear.
- Ulcer care: Debridement, dressings, offloading pressure.

⭐ Charcot foot (neuroarthropathy) is a severe complication causing bone destruction, subluxation, and foot deformity in neuropathic patients.

High‑Yield Points - ⚡ Biggest Takeaways

Annual screening for retinopathy, nephropathy (urine albumin/creatinine ratio), and neuropathy is crucial.

ACE inhibitors or ARBs are first-line for diabetic nephropathy, even with normal blood pressure.

Diabetic foot ulcers are a major risk; perform a comprehensive foot exam annually.

Painful diabetic neuropathy is commonly treated with gabapentin or pregabalin.

Macrovascular disease (CAD, stroke) is the leading cause of death; manage lipids and blood pressure aggressively.

Screen asymptomatic adults for T2DM starting at age 35.

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