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

Diabet Med. 2004 May;21(5):468-70. doi: 10.1111/j.1464-5491.2004.01184.x.


Aims: To evaluate the relative contribution of blood glucose levels at different time points of the day to HbA(1c) 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 HbA(1c) 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 HbA(1c) (r = 0.701; r = 0.686; r = 0.620, respectively; P < 0.0001). Multiple linear regression analysis showed that predinner, prebreakfast and post-breakfast glycaemia correlated significantly and independently with HbA(1c). The model accounted for 47.8% of the variance in HbA(1c).

Conclusions: Our study shows that among individual time points, prebreakfast and predinner are those with more influence on HbA(1c) 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.

MeSH terms

  • Blood Glucose / metabolism*
  • Circadian Rhythm*
  • Diabetes Mellitus, Type 1 / blood*
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Linear Models
  • Postprandial Period


  • Blood Glucose
  • Glycated Hemoglobin A