Chronic hyperglycemia but not glucose variability determines HbA1c levels in well-controlled patients with type 2 diabetes

Diabetes Res Clin Pract. 2007 Sep;77(3):420-6. doi: 10.1016/j.diabres.2007.01.021. Epub 2007 Feb 28.

Abstract

To determine the relationships between HbA1c, characteristics of hyperglycemia and glycemic variability in well-controlled type 2 diabetes (HbA1c<7.0%), we studied 63 primary-care patients (36 men and 27 women), aged 34-75 years, with type 2 diabetes for 2-32 years using a continuous glucose monitoring system (CGMS) and standardized meal test (MMT). Duration of hyperglycemia (>8.0 mmol/l), standard deviation score (S.D.-score) and mean amplitude of glycemic excursions (MAGE) were analyzed from CGMS data and postprandial glucose during MMT (PPG(MMT)). Patients were hyperglycemic for 5.7h/day (median), experienced 4.1 hyperglycemic episodes/day, and 78% exceeded PPG levels of 8.0 mmol/l. HbA1c, though associated with the extent of hyperglycemia (r=0.40, p<0.001), failed to correlate with S.D.-score and MAGE. Multiple regression analysis demonstrated that HbA1c was predicted only by fasting glucose (R(2)=0.24, p<0.001) but neither by PPG(MMT), duration of hyperglycemia, S.D.-score nor MAGE. CGMS and meal test provide the tools for complete characterization of glycemia in type 2 diabetes. In well-controlled type 2 diabetes, HbA1c correlates with chronic hyperglycemia but not with glucose variability. Our data suggest that chronic sustained hyperglycemia and glucose fluctuations are two independent components of dysglycemia in diabetes.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Glucose / analysis*
  • Chronic Disease
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / metabolism*
  • Diet*
  • Female
  • Germany
  • Glycated Hemoglobin / analysis*
  • Humans
  • Hyperglycemia / blood*
  • Male
  • Middle Aged
  • Prospective Studies

Substances

  • Blood Glucose
  • Glycated Hemoglobin A