What is the relative contribution of blood glucose levels at different time points of the day to HbA1c in Type 1 diabetes?

Abstract

Aims: To evaluate the relative contribution of blood glucose levels at different time points of the day to HbA1c in Type 1 diabetes. Methods: Consecutive home blood glucose records (n = 146) from 71 Type 1 diabetic patients who were on an intensive diabetes therapy programme were examined. Each home blood glucose record included six daily blood glucose profiles over 2 months. The relationship between glycaemic values at each time point and HbA1c measured at the end of each record period was analysed. Results: Significant linear correlations were found between HbA 1c and glycaemia at each time point of the day (ranged from 0.413 to 0.593), the strongest being with predinner glycaemia (r = 0.593; P = 0.000). Total daily glycaemia, mean preprandial and mean postprandial glycaemia were also significant and linearly correlated with HbA1c (r = 0.701; r = 0.686; r = 0.620, respectively; P < 0.0001). Multiple linear regression analysis showed that predinner, pre-breakfast and post-breakfast glycaemia correlated significantly and independently with HbA1c. The model accounted for 47.8% of the variance in HbA1c. Conclusions: Our study shows that among individual time points, prebreakfast and predinner are those with more influence on HbA1c in Type 1 diabetes and, to a lesser extent, post breakfast. It also confirms that preprandial glycaemia better predicts overall glycaemic control in Type 1 diabetes than postprandial glycaemia.