title: Chronic hyperglycemia but not glucose variability determines HbA1c levels in well-controlled patients with type 2 diabetes.
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.
authors.affiliation: Institute of Diabetes Gerhardt Katsch, Greifswalder Strasse 11e, D-17495 Karlsburg, Germany. kohnert@diabetes-karlsberg.de
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Kohnert
authors.forename: Petra
authors.initials: P
authors.lastname: Augstein
authors.forename: Peter
authors.initials: P
authors.lastname: Heinke
authors.forename: Eckhard
authors.initials: E
authors.lastname: Zander
authors.forename: Karolina
authors.initials: K
authors.lastname: Peterson
authors.forename: Ernst-Joachim
authors.initials: EJ
authors.lastname: Freyse
authors.forename: Eckhard
authors.initials: E
authors.lastname: Salzsieder
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D002908:Chronic Disease; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000378:metabolism*; D004032:Diet; D005260:Female; D005858:Germany; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin