According to the WHO classification, what is the diagnostic threshold for fasting blood glucose in the diagnosis of diabetes mellitus?

Explanation

## WHO Diagnostic Criteria for Diabetes Mellitus **Key Point:** The WHO and ADA both recognize a fasting plasma glucose (FPG) of ≥126 mg/dL (≥7.0 mmol/L) as diagnostic for diabetes mellitus. ### Fasting Blood Glucose Categories | FPG Level | Classification | |-----------|----------------| | <100 mg/dL | Normal | | 100–125 mg/dL | Impaired fasting glucose (IFG) | | ≥126 mg/dL | Diabetes mellitus | **High-Yield:** This threshold (126 mg/dL) is based on the epidemiological observation that microvascular complications (particularly retinopathy) begin to increase at this glucose level. The value has remained consistent across WHO, ADA, and Indian guidelines since 1997. **Clinical Pearl:** Fasting is defined as no caloric intake for at least 8 hours. A single elevated FPG must be confirmed on a separate day unless accompanied by classic symptoms (polyuria, polydipsia, weight loss) and a random plasma glucose ≥200 mg/dL. ### Alternative Diagnostic Methods - **2-hour post-load glucose (OGTT):** ≥200 mg/dL - **HbA1c:** ≥6.5% (≥48 mmol/mol) - **Random plasma glucose:** ≥200 mg/dL with symptoms