Cannabis use may quadruple diabetes risk

Cannabis use is increasing globally with an estimated 219 million users (4.3% of the global adult population) in 2021, but its long-term metabolic effects remain unknown. While some studies have suggested potential anti-inflammatory or weight management properties, others have raised concerns regarding glucose metabolism and insulin resistance, and the magnitude of the risk for developing diabetes hasn’t been clear.

To strengthen the evidence base, Dr Ibrahim Kamel from the Boston Medical Center, Massachusetts, USA and colleagues analyzed electronic health records from 54 healthcare organizations (TriNetX Research Network, with centers from across USA and Europe) to identify 96,795 outpatients (aged between 18 and 50 years, 52.5% female) with cannabis-related diagnoses (ranging from occasional use to dependence, including cases of intoxication and withdrawal) between 2010 and 2018.

They were matched with 4,160,998 healthy individuals (with no record of substance use or major chronic conditions) based on age, sex, and underlying illnesses at the start of the study, and followed for 5 years.

After controlling HDL and LDL cholesterol, uncontrolled high blood pressure, atherosclerotic cardiovascular disease, cocaine use, alcohol use and several other lifestyle risk factors, the researchers found that new cases of diabetes were significantly higher in the cannabis group (1,937; 2.2%) compared to the healthy group (518; 0.6%), with statistical analysis showing cannabis users at nearly four times the risk of developing diabetes compared to non-users.

While the authors note that more research is needed to fully explain the association between cannabis and diabetes, it may come down to insulin resistance and unhealthy dietary behaviours. Nevertheless, the study's results have immediate implications for metabolic monitoring practices and public health messaging.

“As cannabis becomes more widely available and socially accepted, and legalized in various jurisdictions, it is essential to understand its potential health risks,” said lead author Dr Kamel. “These new sights from reliable real-world evidence highlight the importance of integrating diabetes risk awareness into substance use disorder treatment and counseling, as well as the need for healthcare professional to routinely talk to patients about cannabis use so that they can understand their overall diabetes risk and potential need for metabolic monitoring.”

The authors note that more research is needed on the long-term endocrine effects of cannabis use and whether diabetes risks are limited to inhaled products or other forms of cannabis such as edibles.

Despite the important findings, this is a retrospective study and cannot prove that cannabis use causes diabetes, and the authors cannot rule out the possibility that other unmeasured factors may have influenced the results despite efforts to reduce confounding bias via propensity score matching. This study has limitations due to lack of detailed cannabis consumption data and potential misclassification. The authors acknowledge inherent limitations of real-world data often result from inconsistent patient reporting in electronic medical records. They also note that there is a risk of bias because of imprecise measures of cannabis exposure and the reliance on participants to accurately report any cannabis use, even when they lived in places where the drug is illegal.