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 31-year-old G1P0 woman at 26 weeks gestation presents to the clinic for evaluation of an abnormal glucose tolerance test. She denies any symptoms, but states that she was given 50 g of oral glucose 1 week earlier and demonstrated a subsequent venous plasma glucose level of 156 mg/dL 1 hour later. The vital signs are: blood pressure, 112/78 mm Hg; pulse, 81/min; and respiratory rate, 16/min. Physical examination is within normal limits. Which of the following is the most appropriate next step in management?

Administer an oral, 3-hour 100 g glucose dose

Advise the patient to follow an American Diabetic Association diet plan

Repeat the 50 g oral glucose challenge

Order a fetal ultrasound examination

A 37-year-old woman, gravida 3, para 2, at 28 weeks' gestation comes to the physician for a follow-up examination. One week ago, an oral glucose tolerance screening test showed elevated serum glucose levels. She has complied with the recommended diet and lifestyle modifications. Over the past week, home blood glucose monitoring showed elevated fasting and post-prandial blood glucose levels. Which of the following describes the mechanism of action of the most appropriate pharmacotherapy for this patient?

Binding to receptors with tyrosine kinase activity

Inhibition of alpha-glucosidase

Closure of ATP-dependent K+-channels

Inhibition of dipeptidyl peptidase 4

Activation of peroxisome proliferator-activated receptor-gamma

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 31-year-old G3P2 who is at 24 weeks gestation presents for a regular check-up. She has no complaints, no concurrent diseases, and her previous pregnancies were vaginal deliveries with birth weights of 3100 g and 4180 g. The patient weighs 78 kg (172 lb) and is 164 cm (5 ft 5 in) in height. She has gained 10 kg (22 lb) during the current pregnancy. Her vital signs and physical examination are normal. The plasma glucose level is 190 mg/dL after a 75-g oral glucose load. Which of the listed factors contributes to the pathogenesis of the patient’s condition?

Insulin antagonism of human placental lactogen

Decrease in insulin gene expression

Production of autoantibodies against pancreatic beta cells

Decrease in insulin sensitivity of maternal tissues caused by alpha-fetoprotein

Point mutations in the gene coding for insulin

A 22-year-old Caucasian G1 presents to her physician at 29 weeks gestation for a checkup. The medical history is unremarkable and the current pregnancy has been uncomplicated. Her weight is 81 kg (178.6 lb) and the height is 169 cm (5 ft 6 in). She has gained 13 kg (28.6 lb) during the pregnancy. She has no abnormalities on physical examination. Which of the following screening tests should be obtained ?

Non-fasting oral glucose challenge test with 50 g of glucose

Fasting oral glucose test with 50 g of glucose

Non-fasting oral glucose load test with 75 g of glucose

A 36-year-old primigravida presents to her obstetrician for antenatal care. She is at 24 weeks of gestation and does not have any current complaint except for occasional leg cramps. She does not smoke or drink alcohol. Family history is irrelevant. Her temperature is 36.9°C (98.42°F), blood pressure is 100/60 mm Hg, and pulse of 95/minute. Her body mass index is 21 kg/m² (46 pounds/m²). Physical examination reveals a palpable uterus above the umbilicus with no other abnormalities. Which of the following screening tests is suitable for this patient?

Oral glucose tolerance test for gestational diabetes mellitus

Fasting and random glucose testing for gestational diabetes mellitus

HbA1C for gestational diabetes mellitus

Complete blood count for iron deficiency anemia

Wet mount microscopy of vaginal secretions for bacterial vaginosis

Gestational diabetes management for USMLE Step 1: High-Yield OB/GYN Lessons

GDM Screening - The Sugar Gauntlet

Universal Screening: All patients at 24-28 weeks gestation.
Early Screening (1st trimester): For high-risk patients (obesity, prior GDM).

⭐ 3-hr OGTT Diagnostic Criteria (Carpenter-Coustan):

Fasting: ≥ 95 mg/dL

1 hr: ≥ 180 mg/dL

2 hr: ≥ 155 mg/dL

3 hr: ≥ 140 mg/dL

Oral Glucose Tolerance Test (OGTT) for Diabetes Diagnosis

GDM Diagnosis - The Sweet Verdict

The two-step approach is most common in the US.

3-hr OGTT Diagnostic Criteria (Carpenter-Coustan):
- Fasting: > 95 mg/dL
- 1-hr: > 180 mg/dL
- 2-hr: > 155 mg/dL
- 3-hr: > 140 mg/dL

⭐ One-Step Alternative: The IADPSG criteria uses a 2-hr 75g OGTT. GDM is diagnosed if even one value exceeds the threshold (Fasting >92, 1-hr >180, 2-hr >153).

Gestational Diabetes Diagnosis: 1-Step vs. 2-Step

GDM Management - Taming the Tide

Cornerstone: Lifestyle modification.
- Dietary counseling (low glycemic index) & regular exercise.
- Self-monitoring of blood glucose (SMBG) 4x/day.
Glycemic Targets:
- Fasting: < 95 mg/dL
- 1-hr postprandial: < 140 mg/dL
- 2-hr postprandial: < 120 mg/dL

Pharmacotherapy:
- 1st Line: Insulin (gold standard; no placental crossing).
- Alternatives: Metformin, Glyburide.
Fetal Surveillance:
- Start at 32-34 wks if on meds (NST, BPP).
- Growth US for macrosomia.

⭐ Postpartum Follow-up: All patients require screening for overt DM at 6-12 weeks postpartum using a 75g 2-hr OGTT.

Postpartum Care - The Aftermath

Screening: All women with a history of GDM require lifelong screening for Type 2 Diabetes (T2DM).
Breastfeeding: Encouraged; it ↓ maternal glucose levels and may ↓ the risk of T2DM.

Timing	Screening Test
4-12 weeks postpartum	75-g 2-hour Oral Glucose Tolerance Test (OGTT)
Every 1-3 years thereafter	Assess glycemic status (A1c, FPG, or 75-g OGTT)

High‑Yield Points - ⚡ Biggest Takeaways

Initial management of GDM is always diet and exercise.

Insulin is the first-line medication if lifestyle changes fail; it does not cross the placenta.

Metformin and glyburide are oral options but carry risks like placental transfer (metformin) or neonatal hypoglycemia (glyburide).

Key glucose targets: fasting <95, 1-hr postprandial <140, and 2-hr postprandial <120 mg/dL.

Poor control risks fetal macrosomia, shoulder dystocia, and preeclampsia.

Screen for overt diabetes at 6-12 weeks postpartum with a 75g 2-hour OGTT.

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