Normal Blood Glucose Ranges for Home Monitoring
For home blood glucose monitoring in adults with diabetes, target pre-breakfast (fasting) glucose of 80-130 mg/dL and post-meal glucose <180 mg/dL measured 1-2 hours after starting the meal. 1, 2
Pre-Breakfast (Fasting) Targets
The preprandial capillary plasma glucose target is 80-130 mg/dL (4.4-7.2 mmol/L) for most nonpregnant adults with diabetes. 3, 1, 2
The lower limit was raised from 70 mg/dL to 80 mg/dL to provide a safety margin and limit overtreatment in patients using glucose-lowering medications. 2
Blood glucose <70 mg/dL (3.9 mmol/L) is considered clinically important hypoglycemia requiring immediate treatment with 15-20g of fast-acting carbohydrate. 3, 2
Blood glucose <54 mg/dL (3.0 mmol/L) represents Level 2 hypoglycemia where neuroglycopenic symptoms begin and indicates serious, clinically important hypoglycemia. 3, 2
Post-Meal Targets
Peak postprandial capillary plasma glucose should be <180 mg/dL (10.0 mmol/L) for most nonpregnant adults with diabetes. 3, 1
Postprandial measurements should be taken 1-2 hours after the beginning of the meal, which generally captures peak glucose levels. 3, 1
This <180 mg/dL target has remained consistent across American Diabetes Association guidelines from 2004 through 2024, indicating strong consensus. 1
When to Focus on Post-Meal Monitoring
Postprandial glucose monitoring becomes particularly important when A1C goals are not met despite achieving preprandial glucose targets. 1, 2
If preprandial values are within target (80-130 mg/dL) but A1C remains elevated, checking postprandial glucose identifies areas for improvement. 1
Targeting postprandial values <180 mg/dL can help lower A1C when intensifying therapy. 1
Monitoring Frequency and Timing
Individuals on intensive insulin therapy (multiple daily injections or pump) should check glucose before meals and snacks, at bedtime, occasionally postprandially, and before/during/after exercise. 3
For many individuals using blood glucose monitoring, this requires checking 6-10 times daily, though individual needs vary. 3
More frequent monitoring is reasonable when glycemia is unstable, patients are prone to hypoglycemia, or treatment changes are made. 3
Practical Context from Research Data
Research from the ADAG study shows that to achieve an A1C of 7.0-7.49%, the average fasting blood glucose was 152 mg/dL (143-162 mg/dL) and postmeal glucose was 152 mg/dL (147-157 mg/dL). 4
People achieving A1C <7.5% typically have approximately 60% of blood glucose readings in the 72-180 mg/dL range, with up to 30% of readings >180 mg/dL still being compatible with good control. 5
In people without diabetes, mean premeal glucose is 93 mg/dL and mean peak postmeal glucose is 143 mg/dL, providing context for therapeutic targets. 6
Common Pitfalls to Avoid
Do not rely solely on fasting glucose or A1C to assess glycemic control, as postprandial excursions can be missed. 1
Avoid measuring postprandial glucose at inconsistent times; standardize at 1-2 hours after meal start to capture peak levels. 1
Do not ignore postprandial glucose when A1C goals are not met despite good fasting values, as this indicates excessive postprandial excursions requiring specific intervention. 1
Avoid setting targets too low (<80 mg/dL fasting) as this increases hypoglycemia risk without clear benefit. 2