HbA_1c after a short period of monotherapy with metformin identifies durable glycemic control among adolescents with type 2 diabetes

OBJECTIVE To determine whether clinically accessible parameters early in the course of youth-onset type 2 diabetes predict likelihood of durable control on oral therapy. RESEARCH DESIGN AND METHODS TODAY was a randomized clinical trial of adolescents with type 2 diabetes. Two groups, including participants from all three treatments, were defined for analysis: 1) those who remained in glycemic control for at least 48 months of follow-up and 2) those who lost glycemic control before 48 months. Outcome group was analyzed in univariate and multivariate models as a function of baseline characteristics (age, sex, race/ethnicity, socioeconomic status, BMI, waist circumference, Tanner stage, disease duration, depressive symptoms) and biochemical measures (HbA_1c, C-peptide, lean and fat body mass, insulin inverse, insulinogenic index). Receiver operating characteristic curves were used to analyze HbA_1c cut points. RESULTS In multivariate models including factors significant in univariate analysis, only HbA_1c and insulinogenic index at randomization remained significant (P < 0.0001 and P = 0.0002, respectively). An HbA_1c cutoff of 6.3% (45 mmol/mol) (positive likelihood ratio [PLR] 3.7) was identified that optimally distinguished the groups; sex-specific cutoffs were 6.3% (45 mmol/mol) for females (PLR 4.4) and 5.6% (38 mmol/mol) for males (PLR 2.1). CONCLUSIONS Identifying youth with type 2 diabetes at risk for rapid loss of glycemic control would allow more targeted therapy. HbA_1c is a clinically accessible measure to identify high risk for loss of glycemic control on oral therapy. Adolescents with type 2 diabetes unable to attain a non-diabetes range HbA_1c on metformin are at increased risk for rapid loss of glycemic control.