Abstract Ulnar nerve entrapment (UNE) is a common disorder with many associated risk factors. Diabetes mellitus (DM) is an established risk factor, but less is known about metabolic risk factors in individuals without diabetes. Our study aimed to explore the association of body mass index (BMI) with UNE during long-term follow-up. The population-based cohort study Malmö Diet and Cancer Study (MDCS) and the Swedish Patient Register (NPR) were cross-linked.