We examined a novel linkage of national US donor registry data with records from a pharmacy claims warehouse (2007‐2016) to examine associations (adjusted hazard ratio, LCLaHRUCL) of post‐donation fills of antidiabetic medications (ADM, insulin or non‐insulin agents) with body mass index (BMI) at donation and other demographic and clinical factors. In 28 515 living kidney donors (LKDs), incidence of ADM use at 9 years rose in a graded manner with higher baseline BMI: underweight, 0.9%; normal weight, 2.1%; overweight, 3.5%; obese, 8.5%. Obesity was associated with higher risk of ADM use compared with normal BMI (aHR, 3.364.596.27). Metformin was the most commonly used ADM and was filled more often by obese than by normal weight donors (9‐year incidence, 6.87% vs 1.85%, aHR, 3.555.007.04). Insulin use was uncommon and did not differ significantly by BMI. Among a subgroup with BMI data at the 1‐year post‐donation anniversary (n = 19 528), compared with stable BMI, BMI increase >0.5 kg/m2 by year 1 was associated with increased risk of subsequent ADM use (aHR, 1.031.482.14,
P= .04). While this study did not assess the impact of donation on the development of obesity, these data support that among LKD, obesity is a strong correlate of ADM use.