Lower Values for Postprandial Blood Glucose
The recommended lower value for postprandial blood glucose is 70 mg/dL (3.9 mmol/L), which represents the threshold below which hypoglycemia is defined in diabetic patients. 1
Postprandial Glucose Targets by Population
For Non-Pregnant Adults with Diabetes
- Peak postprandial capillary plasma glucose should be <180 mg/dL (10.0 mmol/L) 1
- Postprandial measurements should be taken 1-2 hours after the beginning of a meal 1
- Preprandial (fasting) glucose targets are 80-130 mg/dL (4.4-7.2 mmol/L) 1
For Pregnant Women with Gestational Diabetes (GDM)
- 1-hour postprandial target: <140 mg/dL (7.8 mmol/L) 1, 2
- 2-hour postprandial target: <120 mg/dL (6.7 mmol/L) 1, 2
- Fasting plasma glucose target: <95 mg/dL (5.3 mmol/L) 1, 2
For Pregnant Women with Pre-existing Diabetes
- Peak postprandial glucose target: 100-129 mg/dL (5.4-7.1 mmol/L) 1, 2
- Premeal, bedtime, and overnight glucose target: 60-99 mg/dL (3.3-5.4 mmol/L) 1
Clinical Significance of Postprandial Glucose
- Postprandial hyperglycemia contributes to elevated A1C levels, with its relative contribution being greater at A1C levels closer to 7% 1
- Elevated postprandial glucose has been associated with increased cardiovascular risk independent of fasting plasma glucose in some epidemiological studies 3
- Surrogate measures of vascular pathology, such as endothelial dysfunction, are negatively affected by postprandial hyperglycemia 1
When to Monitor Postprandial Glucose
- Postprandial glucose monitoring is recommended for individuals who have premeal glucose values within target but A1C values above target 1
- When intensifying insulin therapy, measuring postprandial glucose can help optimize treatment 1
- In GDM, both fasting and postprandial monitoring are essential for optimal glucose control 2
Hypoglycemia Considerations
- Blood glucose <70 mg/dL (3.9 mmol/L) is considered clinically important hypoglycemia regardless of symptoms 1
- Blood glucose <54 mg/dL (3.0 mmol/L) is the threshold at which neuroglycopenic symptoms begin to occur (Level 2 hypoglycemia) 1
- Treatment for hypoglycemia should be approximately 15-20g of glucose, followed by reassessment after 15 minutes 1
Clinical Pearls
- Postprandial glucose naturally rises after meals, with peak levels typically occurring 30-60 minutes after eating in non-diabetic individuals 4
- For individuals without diabetes, postprandial glucose levels typically remain below 140 mg/dL, even at peak 4
- Reactive hypoglycemia can occur 2-5 hours after food intake, with glucose potentially dropping below 55-60 mg/dL 5
- The composition of meals affects glucose rise, and individual variation in insulin response affects postprandial glucose excursions 4
By understanding both the upper and lower boundaries of normal postprandial glucose, clinicians can better identify abnormal patterns and optimize treatment strategies for patients with diabetes or glucose metabolism disorders.