Background: The rising global incidence of diabetes poses a major health challenge, with growing evidence linking diabetes mellitus (DM) and ambient temperature. Due to compromised heat stress responses, people with diabetes are more vulnerable to extreme weather, common comorbidities, insulin resistance, and chronic inflammation. This study examines the impact of ambient temperature on healthcare utilization among diabetes patients in Jakarta, Indonesia, using data from the National Health Insurance program. Method: The study used 2015–2023 sample data from Indonesia's Healthcare and Social Security Agency (BPJS Health), comprising 2,407,300 participants diagnosed with DM. Claims data were stratified by residence, DM type, and healthcare facility type (primary vs. referral care). These were linked with daily, weekly, and monthly temperature records obtained from the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). Negative binomial regression model were applied to assess associations between temperature and DM-related healthcare visits, as the data indicated overdispersion in the count outcomes. Results: Higher daily average temperatures were associated with increased healthcare visits, particularly in primary care. A 1 °C increase in the 7-day average temperature was associated with a 3 % rise in patient visits, while a 14-day average increase was linked to a 4 % rise. Lag structures reduced daily variability, highlighting consistent associations. Utilization patterns also showed peaks on Mondays and declines on weekends and public holidays. Conclusions: Diabetic patients are vulnerable to elevated temperatures, potentially due to impaired thermoregulation and medication effects. As climate change exacerbates extreme temperatures, Jakarta's healthcare system may face increased demand. Interventions such as access to cool public spaces, enhanced patient monitoring, and resilient healthcare infrastructure are recommended. © 2025 The Authors