Association of the Average Rate of Change in HbA1c With Severe Adverse Events: A Longitudinal Evaluation of Audit Data From the Bavarian Disease Management Program for Patients With Type 2 Diabetes Mellitus
Bonke FC, Donnachie E, Schneider A, Mehring M Diabetologia. 2016;59:286-293
This observational study evaluated the association between glycated hemoglobin (A1c) variability and cardiovascular events, emergency admissions, and episodes of severe hypoglycemia among 13,777 patients with type 2 diabetes and newly initiated insulin therapy. The investigators calculated variability using differences between A1c measurements scaled according to length of time between measurements, thereby producing a standardized rate of change.
The outcomes of interest were new occurrence of myocardial infarction (MI), stroke, hypoglycemia that required medical attention, and unplanned hospitalizations related to complications of diabetes. Increase in risk for each of these four outcomes was assessed with Cox models that controlled for age, sex, smoking status, baseline A1c, diabetes duration longer than 8 years (median), the presence of cardiovascular disease (CVD), peripheral artery disease, diabetic complications (retinopathy, neuropathy, or nephropathy), and previous MI, stroke, or diabetes-related emergency admission.
Low (But Not No) Variability May Be Optimal
Most patients (56%) had low A1c variability (0%-0.49% per quarter), and about one third had moderate variability (0.5%-1%). The lowest risk for the outcomes of MI, stroke, and severe hypoglycemia was seen with a variability of approximately 0.5% per quarter, with greater risk for patients with both lower and higher variability.
