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

• Published in: Diabetic medicine Vol. 21; no. 5; pp. 468 - 470
• Main Authors: Hillman, N., Herranz, L., Grande, C., Vaquero, P. M., Pallardo, L. F.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-05-2004; Blackwell
• Subjects: Biological and medical sciences; Blood Glucose - metabolism; Circadian Rhythm; Diabetes Mellitus, Type 1 - blood; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; glucose profiles; Glycated Hemoglobin A - metabolism; HbA1c; Humans; Linear Models; Medical sciences; postprandial glycaemia; Postprandial Period; preprandial glycaemia; Type 1 diabetes; Endocrinopathy; Immunopathology; Type 1 diabetes; Hemoglobin A1c; Postprandial; preprandial glycaemia; postprandial glycaemia; Autoimmune disease; glucose profiles; Glucose; HbA1c; Glycemia
• ISSN: 0742-3071; 1464-5491
• 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 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 HbA1c 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, prebreakfast 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.
Diabet. Med. (2004)