Overweight and obesity are increasingly common among people living with type 1 diabetes (T1D). They may promote insulin resistance, increase insulin requirements, and make it more difficult to achieve individualized glycemic targets. In French Guiana, these challenges may be amplified by economic insecurity, cultural heterogeneity, and barriers to healthcare access. The primary objective of this study was to assess the association of overweight and obesity with glycemic control and metabolic parameters in adults with autoimmune diabetes in French Guiana.

We conducted an observational study using data from the prospective multicenter CODIAM cohort, conducted in French Guiana between 2019 and 2021. Adult patients with classic T1D or latent autoimmune diabetes in adults (LADA) were included. BMI was classified into three categories: normal weight, overweight, and obesity. The glycemic target was individualized at 7% or 8% according to age, diabetes duration, and comorbidities.

Among 76 participants (mean age 43 years, mean BMI 24.7 ± 4.2 kg/m²), 40.8% had BMI ≥25 kg/m² and 75% experienced financial hardship; LADA accounted for 43.4% of cases. Among the 68 patients for whom glycemic data was available during the two-year follow-up, 63.2% of patients never achieved their individualized glycemic target, although mean HbA1c values were lower at later visits than at baseline among patients with available follow-up measurements. The proportion of patients who never achieved glycemic control increased across BMI categories. Vitamin D deficiency affected more than two-thirds of patients and was associated with never achieving glycemic control. Higher LDL cholesterol correlated with poor glycemic control during follow-up.

In this French Amazonian cohort, overweight/obesity was frequent and was associated with a more insulin-resistant profile and a lower likelihood of achieving glycemic targets, in a context marked by precarious living conditions and substantial barriers to healthcare access. These findings support a multidimensional approach to care that integrates glycemic control, weight management, cardiometabolic risk, and social determinants of health.