Distribution of blood glucose and the correlation between blood glucose and hemoglobin A1c levels in diabetic outpatients.

PURPOSE OF THE STUDY Tight glycemic control is important for the prevention of microvascular complications in diabetic patients. We examined the reliability of using blood glucose levels measured at various time-points relative to a meal as an index of glycemic control in Japanese diabetic outpatients. Basic procedures followed: We examined the correlation between the fasting blood glucose (FBG) level; the one-hour (1-h), two-hour (2-h), and three-hour (3-h) post breakfast blood glucose (PBBG) levels, the 1 h, 2 h, and 3 h post lunch blood glucose (PLBG) levels and the hemoglobin A1c (HbA1c) levels in Japanese diabetic outpatients. A total of 11451 patient-visits to the Marunouchi Hospital between January 2002 and December 2002 were included in the study. The main findings: The blood glucose levels measured at all of the above time-points were significantly correlated with the HbA1c level. As calculated using local polynomial regression fitting, the FPG, 1-h, 2-h, and 3-h PBBG levels that corresponded to an HbA1c level of 6.5% were 132 mg/dL, 174 mg/dL, 170 mg/dL, and 143 mg/dL, respectively. The FPG and 2-h PBBG levels exhibited a good sensitivity and specificity for predicting a glycemic control corresponding to an HbA1c<5.8%, while the FPG and 3-h PBBG levels exhibited fair sensitivity and specificity for predicting glycemic control corresponding to an HbA1c<6.5%. The principal conclusions: The FBG, 2-hPBBG, and 3-hPBBG levels can be used as rough estimates of glycemic control in Japanese diabetic outpatients.