A large study of more than 4 million adults found that people with a history of cannabis use faced nearly four times the risk of developing type 2 diabetes compared with those who didn’t use cannabis. The research followed participants for five years and raises concerns about possible long-term metabolic harms as cannabis use grows worldwide.
Methods
Researchers at Boston Medical Center analyzed electronic health records from 54 healthcare organizations in the U.S. and Europe using the TriNetX Research Network. They reviewed records from 2010 to 2018 for adults aged 18 to 50. Nearly 97,000 people had cannabis-related diagnoses (ranging from occasional use and intoxication to dependence and withdrawal). These individuals were matched to more than 4 million people without substance-use histories or major chronic conditions. Matching accounted for common diabetes risk factors such as age, sex, and underlying health issues. All participants were tracked for five years to see who developed type 2 diabetes.
Key findings
– During follow-up, 2.2% of cannabis users developed type 2 diabetes versus 0.6% of non-users, translating to nearly four times the risk.
– Survival (diabetes-free) rates were 96.82% for cannabis users and 99.15% for non-users; the modest percentage gap represents thousands of additional diabetes cases given the study’s size.
– The large, multisite sample and real-world clinical data strengthen the relevance of the findings to routine care, though they cannot prove causation.
Possible mechanisms and expert commentary
Lead researcher Ibrahim Kamel, MD, suggested cannabis may raise diabetes risk via overstimulation of the endocannabinoid system (especially the CB1 receptor), which can promote abdominal and liver fat accumulation and insulin resistance. He also noted other possible contributors: increased caloric intake (the “munchies”), low-grade inflammation, oxidative stress, and potential β-cell dysfunction that impair glucose regulation. Lifestyle factors linked to cannabis use, such as lower physical activity and concurrent alcohol or nicotine use, may further elevate risk.
Kamel cautioned that the study included a relatively healthy population without typical diabetes risk factors, indicating even relatively healthy adults might be at increased risk. He emphasized that further research is needed to confirm mechanisms and whether occasional use carries the same risk; he suggested that reducing use and maintaining a healthy diet and caloric awareness could be helpful measures pending more data.
Independent comment
Chad Larson, NMD, DC, who was not involved in the research, recommended waist circumference as an early indicator of insulin resistance (over 40 inches in men and 35 inches in women) even when body weight seems normal. He also advised practical steps like prioritizing evening protein (about 25 grams) to stabilize overnight blood sugar and reduce cannabis-related cravings, and adding brief daily exercise (for example, a 20-minute brisk walk) to improve glucose uptake by muscle—measures that may lower progression toward type 2 diabetes.
Limitations and implications
Because the study used observational clinical records, it cannot establish a direct cause-and-effect relationship, and residual confounding is possible despite matching and statistical adjustments. The data do not clarify whether frequency, dose, or mode of cannabis use changes risk, or whether occasional use is safer. Nonetheless, the association in a large, diverse cohort suggests clinicians and users should be aware of potential metabolic risks and that further prospective research is warranted.
