According to a study published in Diabetes Care, patients with newly diagnosed type 2 diabetes and at least 10 years of survival who had hemoglobin A1c (HbA1c) levels of ≥6.5% for the first year after diagnosis are at an increased risk for future incident of microvascular and macrovascular events and mortality.
To determine the legacy effect of early glycemic control on diabetic complications and death, researchers followed a cohort of 34,737 patients (mean age, 56.8) with newly diagnosed diabetes for an average of 13 years. For various periods of exposure, patients were examined for associations between future complications and HbA1c levels of <6.5%, 6.5% to <7%, 7% to <8%, 8% to <9%, and ≥9%.
Patients with a mean glycemic level of <6.5% in the 0- to 1-year early exposure period were generally older, more likely to be non-Hispanic white, less likely to be current smokers, and had a lower BMI and total cholesterol than patients with higher mean HbA1c levels.
Overall, in the first year after diagnosis, the researchers found that 41.1% of patients had an average HbA1c level of <6.5%, 16.9% had an average of 6.5% to <7%, 13.6% had an average of 7% to <8%, 4.1% had an average of 8% to <9%, and 3.7% had an average of ≥9%.
Via sensitivity analysis, researchers concluded that compared with patients whose HbA1c levels were <6.5% for the 0- to 1-year exposure period, patients with levels ≥6.5% were more likely to experience microvascular and macrovascular events (hazard ratio, 1.204), and patients with levels ≥7% were associated with increased mortality. Furthermore, longer periods of exposure to HbA1c levels of ≥8% were associated with steadily increasing risk for microvascular event and mortality.
Limitations to this study included an inability to assess causality, analyze the effects of prescription medications, and study cause of death.
Despite these and other limitations, the researchers said their findings “underscore the urgency of early diagnosis of diabetes and the future consequences of failing to achieve near-normal glycemia soon after patients are diagnosed with diabetes.”
Laiteerapong N, Ham SA, Gao Y, et al. The legacy effect in type 2 diabetes: Impact of early glycemic control on future complications (the diabetes & aging study) [published online August 13, 2018]. Diabetes Care. doi:0.2337/dc17-1144/-/DC1