30-Minute Postprandial Glucose (PPG) in Healthy, Pre-Diabetic, and Diabetic Individuals

Unlike the 2-hour post-meal glucose test, 30-minute postprandial glucose (PPG) is less commonly used in standard diagnostics but provides insight into early-phase insulin response and glucose tolerance.

Blood Glucose Marker	Healthy Range	Pre-Diabetes	Diabetes
Fasting Blood Glucose (FBG)	70–99 mg/dL (3.9–5.5 mmol/L)	100–125 mg/dL (5.6–6.9 mmol/L)	≥126 mg/dL (≥7.0 mmol/L)
30-Minute Post-Meal (PPG)	~120–160 mg/dL (~6.7–8.9 mmol/L)	160–180 mg/dL (~8.9–10.0 mmol/L)	>180 mg/dL (>10.0 mmol/L)
2-Hour Post-Meal (PPG)	<140 mg/dL (<7.8 mmol/L)	140–199 mg/dL (7.8–11.0 mmol/L)	≥200 mg/dL (≥11.1 mmol/L)
HbA1c (Glycated Hemoglobin)	<5.7% (39 mmol/mol)	5.7–6.4% (39–46 mmol/mol)	≥6.5% (≥48 mmol/mol)

Key Takeaways

Healthy individuals typically see a glucose peak of ~120–160 mg/dL (6.7–8.9 mmol/L) at 30 minutes, followed by a gradual decline.
Pre-diabetics & diabetics often have higher peaks (>160 mg/dL) and slower glucose clearance due to insulin resistance.
PPG is important for detecting early blood sugar dysregulation, even if fasting glucose and HbA1c appear normal.
A rapid return to baseline (~100 mg/dL) by 2 hours is ideal.