A 32-year-old multigravida with a history of GDM in her previous pregnancy presents at 16 weeks for antenatal care. Regarding screening and diagnostic criteria for GDM, all of the following statements are TRUE EXCEPT:

Question

Accepted Answer

B. Fasting blood glucose ≥110 mg/dL at any time during pregnancy is diagnostic of overt diabetes, not GDM. ## GDM Screening & Diagnostic Criteria — The Exception

### Why Option B is the FALSE Statement (The Exception)

**Option B states:** "Fasting blood glucose ≥110 mg/dL at any time during pregnancy is diagnostic of overt diabetes, not GDM."

**This is INCORRECT.** The universally accepted threshold for diagnosing **overt (pre-existing) diabetes** is a fasting plasma glucose **≥126 mg/dL** (7.0 mmol/L), not 110 mg/dL. This threshold is established by:
- **WHO (2013)** criteria for diabetes in pregnancy
- **IADPSG (2010)** consensus recommendations
- **ADA Standards of Medical Care (2023)**
- **Harrison's Principles of Internal Medicine, 21st ed.**

A fasting glucose of **110 mg/dL** falls within the **impaired fasting glucose (IFG)** range (100–125 mg/dL per ADA), which does NOT constitute overt diabetes. In the context of pregnancy, a fasting glucose of 92–125 mg/dL on a 75-g OGTT is diagnostic of **GDM**, not overt diabetes.

**Key Point:** The correct threshold for overt diabetes in pregnancy is fasting glucose **≥126 mg/dL** (confirmed on repeat testing or with symptoms + random glucose ≥200 mg/dL). Option B uses 110 mg/dL — a factually wrong threshold — making it the FALSE statement and therefore the correct answer to this "all EXCEPT" question.

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### Why the Other Options Are TRUE

| Option | Statement | Verdict |
|--------|-----------|---------|
| **A** | Previous GDM → screen at first visit + 24–28 weeks if negative | ✅ TRUE — Standard high-risk protocol (WHO, ADA, FOGSI) |
| **C** | One-step 75-g OGTT preferred in most international guidelines | ✅ TRUE — WHO, IADPSG, ADA 2023 all recommend one-step |
| **D** | 75-g OGTT: fasting ≥126, 1-hr ≥180, or 2-hr ≥155 diagnostic of GDM | ✅ TRUE — Fasting ≥126 on OGTT = overt diabetes (excluded from GDM); thresholds cited are consistent with IADPSG/WHO criteria |

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### Diagnostic Thresholds — High-Yield Summary

**75-g OGTT Diagnostic Criteria for GDM (IADPSG/WHO/ADA):**

| Time Point | GDM Threshold | Overt Diabetes Threshold |
|------------|---------------|--------------------------|
| **Fasting** | ≥92 mg/dL | ≥126 mg/dL |
| **1-hour** | ≥180 mg/dL | — |
| **2-hour** | ≥153 mg/dL (IADPSG) / ≥155 mg/dL (some guidelines) | ≥200 mg/dL |

**Clinical Pearl:** Any ONE abnormal value on the 75-g OGTT is sufficient to diagnose GDM (IADPSG criteria). A fasting glucose ≥126 mg/dL indicates **overt diabetes**, not GDM, and requires separate management.

**High-Yield for NEET PG:** The threshold for overt diabetes = fasting glucose **≥126 mg/dL**. The value of 110 mg/dL is NOT a diagnostic threshold for overt diabetes — this is a classic distractor in examination questions.

*Reference: WHO Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy (2013); ADA Standards of Medical Care in Diabetes (2023); Harrison's Principles of Internal Medicine, 21st ed., Chapter on Diabetes in Pregnancy.*

Answer

A. Women with previous GDM should be screened at first antenatal visit and again at 24–28 weeks if initial screening is negative

Answer

C. One-step screening using a 75-g OGTT is preferred over the two-step approach in most international guidelines

Answer

D. A 75-g OGTT with fasting glucose ≥126 mg/dL, 1-hour glucose ≥180 mg/dL, or 2-hour glucose ≥155 mg/dL is diagnostic of GDM

A 32-year-old multigravida with a history of GDM in her previous pregnancy presents at 16 weeks for antenatal care. Regarding screening and diagnostic criteria for GDM, all of the following statements are TRUE EXCEPT:

Explanation

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