Effect of Early Glycemic Control in Youth-Onset Type 2 Diabetes on Longer-Term Glycemic Control and β-Cell Function: Results From the TODAY Study

Abstract

OBJECTIVE Little is known about the impact of early attainment of tight glycemic control on long-term β-cell function and glycemic control in youth-onset type 2 diabetes. We examined the effect of the initial 6 months of glycemic control on β-cell function and glycemic control longitudinally over 9 years and the impact of sex, race/ethnicity, and BMI on these relationships in adolescents with youth-onset type 2 diabetes in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study. RESEARCH DESIGN AND METHODS Oral glucose tolerance tests were performed longitudinally through year 9 to derive estimates of insulin sensitivity and secretion. Early glycemia was defined by mean HbA1c during the first 6 months postrandomization, categorized into five HbA1c groups (<5.7%, 5.7 to <6.4%, 6.4 to <7.0%, 7.0 to <8.0%, and ≥8.0%). The long-term period was defined as the period between years 2 and 9. RESULTS A total of 656 participants (64.8% female, baseline mean age 14 years, diabetes duration <2 years) had longitudinal data available over an average of 6.4 ± 3.2 years of follow-up. HbA1c significantly increased in all early glycemic groups during years 2–9, with a steeper increase (+0.40%/year) among participants with the tightest initial control (mean early HbA1c <5.7%), in parallel to a decline in the C-peptide–derived disposition index. Nevertheless, the lower HbA1c categories continued to have relatively lower HbA1c over time. CONCLUSIONS Early tight glycemic control in the TODAY study was related to β-cell reserve and translated to better long-term glycemic control. However, tight early glycemic control on the randomized treatment in the TODAY study did not prevent deterioration of β-cell function.