Weight Gain and Glycemic Control in Adults with Type 1 Diabetes in the T1D Exchange Registry

<bold>Aim:</bold> The impact of weight gain on insulin dosage and glycemic control in adults with type 1 diabetes (T1D) aged 25 years and older was investigated in the T1D Exchange Registry participants. <bold>Methods:</bold> Participants were categorized into four groups based on their change in weight from T1D Exchange registry enrollment to year 5: stable weight (-5 to <5 lb), gained 5 to <10 lb, gained 10 to <20 lb, or gained >= 20 lb. Those who lost >5 lb were excluded. The primary outcomes were glucose control, as measured by glycosylated hemoglobin (HbA1c), and total daily insulin dose (TDD) at year 5. Linear regression models were used to evaluate the association between weight gain, HbA1c, and TDD. <bold>Results:</bold> There were 1969 participants included in the analyses. The mean +/- standard deviation age was 45 +/- 13 years, 57% were female, and 92% were White non-Hispanic. For those with an enrollment HbA1c <8.0%, the mean HbA1c at year 5 was higher for those who gained >= 20 lb compared to those with a stable weight of -5 to <5 lb (7.4% +/- 1.1% vs. 7.2% +/- 0.8%, respectively; P = 0.005). For this cohort, the mean TDD at year 5 increased from 49 +/- 25 to 61 +/- 29 U for those who gained >= 20 lb, while decreased from 45 +/- 27 to 44 +/- 25 U for those with stable weight of -5 to <5 lb (P < 0.001). Among participants with an enrollment HbA1c >= 9.0%, the mean HbA1c at year 5 was statistically insignificant at 8.4% +/- 1.3% for those who gained >= 20 lb compared to 9.2% +/- 1.7% for those with a stable weight of -5 to <5 lb (P = 0.09). <bold>Conclusion:</bold> Significant weight gain in adults with T1D who had good to adequate glycemic control was associated with modest deterioration in glucose control despite an increase in TDD. Worsening glucose control may indicate insulin resistance related to weight gain despite significantly increased insulin dosage which was insufficient to maintain adequate glycemic control.