Relationship between Diurnal Glucose Levels and Hb_A1c in Type 2 Diabetes

Abstract

Aims and methods: Study results still conflict on the contribution of diurnal blood glucose (BG) values to Hb_A1c in type 2 diabetes. We investigated the relationship between Hb_A1c and diurnal BG obtained under standardized conditions - before breakfast, two hours after breakfast, before lunch, two hours after lunch, before dinner, two hours after dinner, and at 10 PM, 12 midnight and 3 AM in 68 type 2 diabetic patients before and after optimizing glycemic control. The areas under the curve above fasting BG (AUC1) and above 5.6 mmol/l (AUC2) were calculated for further evaluation. Hb_A1c was measured at baseline and after a mean of 89 (74 to 108) days. Results: Each BG value at baseline and after treatment optimization significantly correlated with baseline and follow-up Hb_A1c, respectively. The pre-breakfast BG showed the closest correlation with Hb_A1c. The relative contribution of postprandial BG concentrations (AUC1) to overall hyperglycemia (AUC2) decreased with poorer glycemic control. However, treatment optimization mainly resulted in improved blood glucose values in patients with the poorest glycemic control at baseline. Multiple regression analysis demonstrated that fasting (AUC2-AUC1) and postprandial (AUC1) hyperglycemia independently determined Hb_A1c or the change in Hb_A1c after treatment optimization. Conclusions: Our findings indicate that intensive blood glucose monitoring during fasting and postprandial states is important for glycemic control, and is therefore an essential part of good clinical practice.

Hb_A1c - type 2 diabetes - fasting glucose - postprandial glucose

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