Glucose Variability Affects Hemoglobin A_1c

Glycosylated hemoglobin (HbA_1c) levels reflect average blood glucose over several months. However, a 3-month average glucose level of 200 mg/dL, for example, could reflect levels mostly clustered tightly around 200 mg/dL, or it could reflect levels varying widely between 100 and 300 mg/dL. The question: At any given average glucose level, does glucose variability affect HbA_1c?

In a study involving 427 diabetic patients (63% had type 1 diabetes), investigators obtained about 2700 blood glucose measurements per patient during a 3-month period. Glucose variability affected HbA_1c in type 1 diabetic patients. In patients with poor control (average glucose level, 240 mg/dL), low glucose variability (standard deviation, 30 mg/dL) was associated wit…