Predictor variables and an equation for estimating HbA1c attainable by initiation of basal supported oral therapy

Abstract

Aims/Introduction: A method of estimating HbA1c attained after initiation of basal supported oral therapy (BOT) has not been reported previously. The aim of the present study was to determine which characteristics of patients could influence the effectiveness of BOT introduction, and to obtain an equation to estimate HbA1c after BOT initiation. Materials and Methods: Sixty consecutive insulin-naive type 2 diabetic patients with poor glycemic control (HbA1c ≥7.5%) started once-daily injections of insulin glargine. Simple correlations were calculated between parameters such as HbA1c at baseline, HbA1c at week 24, reduction rate of HbA1c over 24weeks (calculated as: [HbA1c level at baseline - HbA1c level at week 24]/HbA1c level at baseline), duration of diabetes, and the number of classes of coadministered oral antidiabetic drugs. Using multiple linear regression models, the independent effects of these parameters on HbA1c at week 24 were evaluated separately. Results: Multiple linear regression analysis revealed that duration of diabetes (β=0.561; P<0.001) and HbA1c at baseline (β=0.284; P=0.006) were significant predictors of HbA1c at week 24. The best fitting multiple regression equation was: HbA1c at week 24=0.078×duration of diabetes+0.218×HbA1c at baseline+4.628 (r 2=0.437). Conclusions: The equation based on the multiple linear regression models indicates necessary conditions for type 2 diabetic patients to achieve target HbA1c. The present findings emphasize the principle that early initiation of BOT in type 2 diabetes effectively achieves good glycemic control. © 2011 Asian Association for the Study of Diabetes and Blackwell Publishing Asia Pty Ltd.