What should a Hemoglobin A1C (HbA1C) level be?

From the Guidelines

For most adults with diabetes, the target Hemoglobin A1C (HbA1C) level should be less than 7%. This target is based on the American Diabetes Association's standards of medical care in diabetes, as outlined in the 2017 guidelines 1. The HbA1C test measures the percentage of hemoglobin proteins in the blood that are coated with sugar, reflecting average blood sugar levels over the past 2-3 months.

Key Considerations for HbA1C Targets

• For individuals with a short duration of diabetes, long life expectancy, or no significant cardiovascular disease, more stringent HbA1C goals (such as <6.5%) may be appropriate, as long as they can be achieved without significant hypoglycemia or other adverse effects 1.
• Less stringent HbA1C goals (such as <8%) may be suitable for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, or extensive comorbid conditions 1.
• The HbA1C level is an indirect measure of glycemia and may not accurately reflect average glycemia in individuals with increased red blood cell turnover or hemoglobin variants 1.

Importance of Regular HbA1C Testing

• Regular HbA1C testing is recommended every 3-6 months for people with diabetes to monitor the effectiveness of their treatment plan 1.
• The frequency of HbA1C testing should depend on the clinical situation, treatment regimen, and clinician's judgment, with more frequent testing for those whose therapy has changed or who are not meeting glycemic goals 1.

Limitations of HbA1C Testing

• HbA1C testing has limitations, including not providing a measure of glycemic variability or hypoglycemia, and being affected by conditions that alter erythrocyte turnover or hemoglobin variants 1.
• Glycemic control is best evaluated by combining results from self-monitoring of blood glucose (SMBG) and HbA1C testing 1.

From the Research

HbA1C Levels

The ideal Hemoglobin A1C (HbA1C) level is a subject of controversy, with different guidelines and studies recommending varying targets.

• The American College of Physicians (ACP) recommends a target HbA1C level between 7% and 8% for most patients with type 2 diabetes 2.
• The American Diabetes Association recommends aiming for HbA1C levels less than 7% for many nonpregnant adults and considering a target of 6.5% if it can be achieved safely 2.
• A study published in the journal Diabetes, metabolic syndrome and obesity: targets and therapy found that the recommended 6.5% threshold distinguishes well between subjects with and without retinopathy 3.
• Another study published in the Journal of diabetes suggests that insulin may not be the preferred treatment for HbA1C levels above 9%, and that other treatments such as metformin, incretin-based treatments, and SGLT2 inhibitors may be more effective 4.
• A meta-analysis published in the journal Cardiovascular diabetology found that relatively tight glucose control resulting in a follow-up HbA1C level above 7.0% was associated with a reduction in major cardiovascular events, while a follow-up HbA1C level below 7.0% was associated with a reduction in non-fatal myocardial infarction 5.
• A study published in the journal Diabetologia found that HbA1C levels were associated with lower risks of macrovascular events and death down to a threshold of 7.0% and microvascular events down to a threshold of 6.5% 6.

Key Findings

• There is no single ideal HbA1C target for all patients with type 2 diabetes.
• Different guidelines and studies recommend varying targets, ranging from 6.5% to 8%.
• The relationship between HbA1C levels and vascular complications and death is non-linear, with evidence of thresholds below which there is no significant change in risks.
• HbA1C levels above 7.0% are associated with increased risks of macrovascular events, microvascular events, and death.

HbA1C Targets

• The American College of Physicians (ACP) recommends a target HbA1C level between 7% and 8% for most patients with type 2 diabetes 2.
• The American Diabetes Association recommends aiming for HbA1C levels less than 7% for many nonpregnant adults and considering a target of 6.5% if it can be achieved safely 2.