Overweight and obesity in adults with type 1 diabetes: associations with glycemic control and cardiometabolic risk.

Purpose: An often-overlooked issue in type 1 diabetes' (T1D) management is the growing prevalence of overweight and obesity, as well as the control of accompanying cardiometabolic risk factors. This cross-sectional study investigates associations of body mass index (BMI) and waist circumference (WC) with glycemic control and other cardiometabolic risk factors in adults with T1D. Methods: Patients followed in the Insulin Pump Clinic at a tertiary hospital were selected. Data from clinical records and continuous glucose monitoring-derived parameters were retrospectively documented, from 2022 to 2024. Associations of BMI and WC categories with cardiometabolic risk factors were assessed using linear regression models. Restricted cubic splines analyses were performed to assess for nonlinear associations. Results: Of the 388 patients included, 32.3% were overweight and 13.7% had obesity. A U-shaped relationship was observed between BMI and glycated hemoglobin (HbA1c), with lower and higher BMI associated with increased HbA1c (p for non-linearity = 0.005). A higher time in range was found in the increased WC group (53.1 ± 18.4% vs. 59.8 ± 14.6%, p = 0.036). Patients with obesity had higher systolic (p = 0.013) and diastolic blood pressure (BP) (p = 0.001), non-high-density lipoprotein (HDL) cholesterol (p = 0.022) and triglycerides (p = 0.001) values, when compared to lower BMI categories. Patients with increased WC also presented higher systolic (p = 0.038) and diastolic BP (p = 0.015), non-HDL (p = 0.010) and triglycerides (p < 0.001) values, compared to those with normal WC. Conclusion: In adults with T1D, BMI and WC showed stronger associations with BP and lipid profile than glycemic control, underscoring the importance of comprehensive cardiovascular risk assessment and targeted therapeutic strategies in this population. Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-025-01718-1.