What are the recommended glucose control ranges for Fasting Blood Sugar (FBS) and Post-Prandial Blood Sugar (PPBS) in a patient with type 2 diabetes mellitus?

Glucose Control Targets in Type 2 Diabetes Mellitus

For adults with type 2 diabetes, maintain fasting blood sugar (FBS) between 80-130 mg/dL and post-prandial blood sugar (PPBS) below 180 mg/dL, measured 1-2 hours after starting a meal. 1, 2

Fasting Blood Sugar (FBS) Targets

The recommended preprandial capillary plasma glucose target is 80-130 mg/dL for most nonpregnant adults with type 2 diabetes. 3, 1, 4

• The lower limit was specifically raised from 70 mg/dL to 80 mg/dL to provide a safety margin and limit overtreatment in patients using glucose-lowering medications, particularly insulin 1, 4
• Blood glucose below 70 mg/dL constitutes clinically important hypoglycemia requiring immediate treatment with 15-20g of fast-acting carbohydrate 1, 4
• Blood glucose below 54 mg/dL represents Level 2 hypoglycemia where neuroglycopenic symptoms begin, indicating serious, clinically important hypoglycemia 1, 4

Post-Prandial Blood Sugar (PPBS) Targets

Peak postprandial capillary plasma glucose should remain below 180 mg/dL, measured 1-2 hours after beginning the meal. 3, 1, 2

• This target has remained consistent across American Diabetes Association guidelines from 2004 through 2024, indicating strong consensus on its importance 3, 2
• Postprandial measurements must be standardized at 1-2 hours after meal start to capture peak glucose levels accurately 1, 2
• When A1C goals are not met despite achieving fasting glucose targets, postprandial glucose monitoring becomes critical to identify excessive postprandial excursions requiring specific intervention 1, 2, 5

Clinical Context and Rationale

Postprandial glucose control accounts for approximately 80% of HbA1c when HbA1c is below 6.2%, but only about 40% when HbA1c exceeds 9.0%. 6

• Research demonstrates that 70% of patients with HbA1c below 7% still have postprandial glucose values exceeding 160 mg/dL after meals 7
• Among type 2 diabetes patients treated with basal insulin who achieve adequate fasting glucose control (below 130 mg/dL), approximately 23.5% still fail to achieve HbA1c targets below 7% due to uncontrolled postprandial excursions 5
• Control of fasting hyperglycemia alone is necessary but usually insufficient for achieving HbA1c goals below 7%; control of postprandial hyperglycemia is essential 6

Monitoring Frequency Based on Treatment Regimen

Patients on intensive insulin therapy should check glucose before meals and snacks, at bedtime, occasionally postprandially, and before/during/after exercise, typically requiring 6-10 checks daily. 1

• For patients on single daily basal insulin injections, daily fasting blood glucose measurements are suggested as the fasting value best reflects the appropriateness of the basal insulin dose 3
• More frequent monitoring is reasonable when glycemia is unstable, patients are prone to hypoglycemia, or treatment changes are made 1

Target Modification Based on Patient Characteristics

More stringent HbA1c targets (6.0-6.5%) may be considered in selected patients with short disease duration, long life expectancy, and no significant cardiovascular disease if achievable without significant hypoglycemia. 3

Less stringent HbA1c goals (7.5-8.0% or slightly higher) are appropriate for patients with:

• History of severe hypoglycemia 3, 4
• Limited life expectancy 3, 4
• Advanced complications 3
• Extensive comorbid conditions 3
• Difficulty attaining targets despite intensive self-management education and multiple glucose-lowering agents including insulin 3

Critical Pitfalls to Avoid

Do not rely solely on fasting glucose or HbA1c to assess glycemic control, as postprandial excursions can be missed entirely. 1, 2

• Ignoring postprandial glucose when A1C goals are not met despite good fasting values is a common error that leaves excessive postprandial excursions unaddressed 1, 2
• Measuring postprandial glucose at inconsistent times should be avoided; standardize at 1-2 hours after meal start 1, 2
• Setting fasting targets too low (below 80 mg/dL) increases hypoglycemia risk without clear benefit 1, 4
• The coefficient of correlation between fasting plasma glucose and HbA1c is only 0.73, meaning fasting glucose alone poorly predicts overall glycemic control 7