Assessing Glycemic Control in Diabetes

HbA1c as the Primary Metric

The American College of Physicians and the American Diabetes Association recommend HbA1c as the primary metric for assessing long-term glycemic control, reflecting average glycemia over approximately 3 months, with strong predictive value for diabetes complications 1, 2
The American Diabetes Association suggests testing HbA1c at least twice per year in patients meeting treatment goals with stable glycemic control, and quarterly in those whose therapy has changed or who are not meeting glycemic goals, with a strength of evidence level of A 1, 3
HbA1c is the metric used in clinical trials demonstrating the benefits of improved glycemic control, with high-quality evidence supporting its use 3
Point-of-care testing for HbA1c allows more timely treatment changes, with moderate-quality evidence supporting its effectiveness 1, 2

The American College of Physicians notes that HbA1c does not measure glycemic variability or hypoglycemia, with low-quality evidence available on its limitations 1, 2
The American Diabetes Association states that HbA1c may not accurately measure average glycemia in persons with increased turnover of red blood cells, with moderate-quality evidence supporting this limitation 1
HbA1c is an indirect measure of glycemia and may not correlate with a patient's measured glucose levels in certain conditions, such as hemoglobinopathies or anemia, with high-quality evidence supporting its limitations 1, 4

The Endocrine Society recommends CGM as a useful tool for assessing glycemic control, providing more detailed information about glycemic patterns, with moderate-quality evidence supporting its use 1, 5
The American Diabetes Association suggests that CGM metrics, particularly time in range, provide a more personalized approach to diabetes management, with low-quality evidence available on its effectiveness
The greatest predictor of HbA1c lowering with CGM for all age groups is frequency of sensor use, with moderate-quality evidence supporting its effectiveness 1, 5

The American Diabetes Association recommends SMBG as an essential tool for day-to-day management, providing point-in-time measurements that help with adjusting therapy, with high-quality evidence supporting its use 5
In patients with type 1 diabetes, increased daily frequency of SMBG was significantly associated with lower HbA1c levels and fewer acute complications, with moderate-quality evidence supporting its effectiveness 5
For patients using intensive insulin regimens, SMBG is essential to adjust therapy and minimize hypoglycemia, with high-quality evidence supporting its use 5, 6

The American Diabetes Association recommends using HbA1c as the foundation for assessing glycemic control, measuring HbA1c every 3-6 months depending on stability of glycemic control, with moderate-quality evidence supporting its use 3, 2
The Endocrine Society suggests incorporating CGM when available, especially for patients on intensive insulin therapy or with problematic hypoglycemia, with moderate-quality evidence supporting its effectiveness 5, 7

For patients with frequent hypoglycemia or hypoglycemia unawareness, CGM provides critical information that HbA1c cannot, with moderate-quality evidence supporting its use 5, 7
In pregnancy, more frequent monitoring and tighter targets are required, with high-quality evidence supporting its importance 5
For elderly patients or those with comorbidities, less stringent HbA1c goals (such as <8%) may be appropriate, with focus on avoiding hypoglycemia, with moderate-quality evidence supporting its use 1, 2

Relying solely on HbA1c without considering glycemic variability or hypoglycemia risk, with low-quality evidence available on its limitations 1
Failing to calibrate glucose meters regularly, which can lead to inaccurate SMBG results, with high-quality evidence supporting its importance 4, 6
Not accounting for conditions that may affect HbA1c accuracy (hemoglobinopathies, anemia, etc.), with moderate-quality evidence supporting its importance 2, 4