Target Blood Glucose Levels for Type 2 Diabetes Mellitus
For most adults with type 2 diabetes, target HbA1c <7.0% (53 mmol/mol), with fasting/premeal glucose <130 mg/dL (7.2 mmol/L) and postprandial glucose <180 mg/dL (10.0 mmol/L). 1
HbA1c Targets Based on Patient Characteristics
The standard HbA1c target of <7.0% reduces microvascular complications, but this must be individualized based on specific clinical factors 1:
More Stringent Targets (HbA1c 6.0-6.5%)
Consider tighter control in patients with: 1
- Short disease duration (newly diagnosed)
- Long life expectancy (younger patients without comorbidities)
- No significant cardiovascular disease
- Ability to achieve target without significant hypoglycemia
Less Stringent Targets (HbA1c 7.5-8.0% or higher)
Use higher targets for patients with: 1
- History of severe hypoglycemia
- Limited life expectancy
- Advanced microvascular or macrovascular complications
- Extensive comorbid conditions
- Difficulty achieving lower targets despite intensive therapy
- Older age (>65 years) 1
Daily Glucose Monitoring Targets
Beyond HbA1c, specific glucose values throughout the day matter significantly 1:
Fasting and Premeal Glucose
- Target: <130 mg/dL (<7.2 mmol/L) 1
- Mean plasma glucose should be 150-160 mg/dL (8.3-8.9 mmol/L) to achieve HbA1c <7.0% 1
Postprandial Glucose
- Target: <180 mg/dL (<10.0 mmol/L) 1
- Measure 1-2 hours after meal initiation 1
- Postprandial hyperglycemia contributes significantly to overall glycemic control even when fasting glucose is controlled 2, 3, 4
Critical Clinical Considerations
Why Both Fasting and Postprandial Targets Matter
Fasting glucose alone is insufficient for assessing glycemic control. Studies show that 70% of patients with HbA1c <7% still have postprandial glucose >160 mg/dL after meals 4. The correlation between fasting glucose and HbA1c is only moderate (r=0.73), meaning patients can have acceptable fasting values but poor overall control 4.
In patients with fasting glucose <130 mg/dL but HbA1c >7%, the most common pattern is elevated glucose at all times (41.7% of cases), followed by high pre-meal and post-meal glucose (36.7%), and isolated postprandial hyperglycemia (21.7%) 2.
Hospitalized Patients
Different targets apply for inpatient management 1:
- Initiate insulin therapy at glucose ≥180 mg/dL (10.0 mmol/L) 1
- Target range: 140-180 mg/dL (7.8-10.0 mmol/L) for most critically ill and non-critically ill patients 1
- More stringent goals of 110-140 mg/dL (6.1-7.8 mmol/L) may be appropriate for selected patients if achievable without significant hypoglycemia 1
Avoiding Common Pitfalls
Do not use percentage of patients achieving HbA1c <7.0% as a quality indicator across populations, as this contradicts the emphasis on individualized treatment goals 1. Each target should reflect an agreement between patient and clinician based on individual risk-benefit assessment 1.
Hypoglycemia avoidance is paramount. Cardiovascular outcome trials demonstrate that not everyone benefits from aggressive glucose management, and tight control (targeting 80-110 mg/dL) increases mortality compared to moderate targets (140-180 mg/dL) 1.
Monitoring Strategy
Regular monitoring should include 1, 5:
- HbA1c every 3 months until target achieved, then every 6 months if stable
- Fasting glucose to assess basal control
- Postprandial glucose to identify meal-related excursions
- Both pre-meal and post-meal measurements correlate significantly with HbA1c (r=0.40-0.47) 2