Hypoglycemia Risk at All HbA1c Levels

The risk of a hypoglycemic event in type 2 diabetes patients was similar among patients across all levels of glycemic control….

The authors analyzed the relationship between HbA1c levels and hypoglycemia among type 2 diabetes patients. Ranging from ages 30 to 77, patients in the study were on their usual medications for diabetes management. The study, which was based on a survey linked to participant’s electronic medical records, looked at the occurrence of diabetes complications, including self-reported hypoglycemic events. The primary endpoint was the incidence of at least one severe hypoglycemic event in the year prior to the "observation period."

Participants’ HbA1c levels were classified as either "near-normal glycemia (less than 6%), very good (6% to 6.9%), good (7% to 7.9%), suboptimal (8% to 8.9%), and very poor (9% or greater)." Furthermore, their diabetes duration was classified as either "10 years or less" or "more than 10 years."

Among the diabetic patients surveyed, 10.8% of them were said to experience severe hypoglycemia, with rates of hypoglycemic events occurring between 9.35 to 13.8% across all HbA1c levels. Results of the study indicated no significant difference between level of HbA1c and risk of severe hypoglycemia. However, risk of a hypoglycemic event occurring tended to be higher in patients with either "near-normal glycemia or very poor glycemic control." Furthermore, it was also found that no significant relationship existed between a patient’s HbA1c level and their age, length of diabetes history, or type of diabetes medication regimen.

In conclusion, diabetic patients who take certain antidiabetic medication and experience hypoglycemia are common across all level of glycemic control. "It is important to note that it’s not the HbA1c that directly causes hypoglycemia, it’s the therapies we use to lower it," said Dr. Lipska. "Future research needs to better identify those patients at the highest risk for hypoglycemia so we can reduce the risk. For now, we know that poor control is certainly not protective."

The authors note that since the study was based on a survey, involving patient self-reported hypoglycemic events, a study limitation was lack of confirmation of hypoglycemia. Its retrospective nature and lack of determining a causal relationship were also limitations.

Lipska KJ, et al "HbA1c and risk of severe hypoglycemia in type 2 diabetes" Diab Care 2013; DOI: 10.2337/dc13-0610