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.

Key words

Hb_A1c - type 2 diabetes - fasting glucose - postprandial glucose

References

• 1 Bonora E, Calcaterra F, Lombardi S. et al. . Plasma glucose levels throughout the day and HbA(1c) interrelationships in type 2 diabetes: implications for treatment and monitoring of metabolic control.  Diabetes Care. 2001;  24 2023-2029
• 2 Bonora E, Muggeo M. Postprandial blood glucose as a risk factor for cardiovascular disease in Type II diabetes: the epidemiological evidence.  Diabetologia. 2001;  44 2107-2114
• 3 Hanefeld M, Fischer S, Julius U. et al. . Risk factors for myocardial infarction and death in newly detected NIDDM: the Diabetes Intervention Study, 11-year follow-up.  Diabetologia. 1996;  39 1577-1583
• 4 Hanefeld M. Postprandial hyperglycaemia: noxious effects on the vessel wall.  Int J Clin Pract Suppl. 2002;  45-50
• 5 Ceriello A, Hanefeld M, Leiter L. et al. . Postprandial glucose regulation and diabetic complications.  Arch Intern Med. 2004;  164 2090-2095
• 6 Avignon A, Radauceanu A, Monnier L. Nonfasting plasma glucose is a better marker of diabetic control than fasting plasma glucose in type 2 diabetes.  Diabetes Care. 1997;  20 1822-1826
• 7 Monnier L, Lapinski H, Colette C. Contributions of fasting and postprandial plasma glucose increments to the overall diurnal hyperglycemia of type 2 diabetic patients: variations with increasing levels of HbA(1c).  Diabetes Care. 2003;  26 881-885
• 8 American Diabetes Association . Clinical practise recommendations (Position Statement): Diabetes care.  2005;  28 37-42
• 9 Hillman N, Herranz L, Grande C, Vaquero PM, Pallardo LF. What is the relative contribution of blood glucose levels at different time points of the day to Hb_A1c in Type 1 diabetes?.  Diabet Med. 2004;  21 468-470
• 10 Bouma M, Dekker JH, de Sonnaville JJ. et al. . How valid is fasting plasma glucose as a parameter of glycemic control in non-insulin-using patients with type 2 diabetes?.  Diabetes Care. 1999;  22 904-907
• 11 Derr R, Garrett E, Stacy GA, Saudek CD. Is HbA(1c) affected by glycemic instability?.  Diabetes Care. 2003;  26 2728-2733
• 12 Bastyr EJ, III, Stuart CA, Brodows RG. et al. . Therapy focused on lowering postprandial glucose, not fasting glucose, may be superior for lowering Hb_A1c. IOEZ Study Group.  Diabetes Care. 2000;  23 1236-1241
• 13 Buse JB. Should postprandial glucose be routinely measured and treated to a particular target? Connecting the two sides of the debate.  Diabetes Care. 2003;  26 2700-2701
• 14 Abrahamson MJ. Optimal glycemic control in type 2 diabetes mellitus: fasting and postprandial glucose in context.  Arch Intern Med. 2004;  164 486-491

Correspondence