Marijuana Use Linked to Prediabetes
Does cannabis protect against blood sugar problems…or ignite them? Several big population studies hint at an intriguing association between marijuana and lower risk for type 2 diabetes. But a recent University of Minnesota study has uncovered 49-65% higher odds for prediabetes in current smokers and former “heavy” users. The study was published in the September issue of the journal Diabetologia.
Researchers used data from the large, on-going CARDIA (Coronary Artery Risk Development in Young Adults) study, which is studying heart disease development in 5,115 black and Caucasian women and men over several decades. For this study, they looked at associations between marijuana use and blood-sugar levels in a group of 3,034 study volunteers 25 years after the study began in the mid-1980s. They also looked at 3,151 volunteers who did not have prediabetes or diabetes in 1992-1993 to see, in follow-up exams, how blood sugar levels changed for pot users and abstainers.
Overall, marijuana use dropped from 28% at the start of the study to 12% by 2010. By then, current smokers had a 65% higher risk for prediabetes. And former users who smoked or otherwise ingested marijuana at least 100 times in the past had a 49% higher risk for prediabetes. But pot wasn’t associated with higher risk for full-blown type 2 diabetes. “Marijuana may have a more noticeable impact on glycemic metabolism in the prediabetes range compared with the diabetes range,” says lead researcher Michael Bancks, a doctoral student at the University of Minnesota School of Public Health. In contrast, traditional risk factors like obesity may overshadow the effects of marijuana in people who do develop diabetes, he adds.
THC and A1c
Nearly 19 million Americans use marijuana. But “despite the growing movement to legalize marijuana, little is known about its effect on metabolic health,” Bancks and his coauthors from the University of California, San Francisco, the University of Alabama at Birmingham and Kaiser Permanente Northern California note in the study.
A string of epidemiological studies have turned up an association between the drug and lower risk for diabetes. In a 2013 study from Harvard Medical School of the health records of 4,657 people, marijuana users had lower fasting insulin levels and less insulin resistance than non-users. And in July of 2015, Michigan State University researchers analyzed eight studies and found a 30% lower diabetes risk for current marijuana users. They concluded that “current evidence is too weak for causal inference” but that marijuana’s effects on blood sugar were worth more study.
Researchers aren’t sure what might be at work. But they (and cannabis fans) do know that tetrahydrocannabinol — THC, the major “active ingredient” in marijuana—stimulates the body’s endocannabinoid system, which helps regulate appetite (explaining the “munchies”), impulse control and body weight as well as blood sugar. Lab studies looking at THC’s role more directly have found that, at least in rats, THC seemed to protect against high blood sugar.
But it’s not clear how beneficial marijuana or THC may be. When National Institutes of Health researchers took a closer look at the metabolic health of 30 cannabis smokers and 30 non-smokers, they found that marijuana users had more abdominal fat and their fat cells were more insulin resistant. And other studies have found higher blood-sugar and insulin levels among former users compared to nonusers, according to a 2013 University of Miami review. Burning cannabis also releases substances that can damage cells, Bancks notes. “Marijuana smoke is shown to increase the production of reactive oxygen species and oxidative stress,” he says. “This means the overall physiological process occurring with marijuana use may be complex.”
Good for Blood Sugar? Not Yet
So, should you smoke, or snack on brownies spiced with cannabis, for your blood sugar? “There is not enough evidence to start using marijuana for diabetes prevention or diabetes treatment for that matter,” says registered dietitian and certified diabetes educator Amy Hess-Fischl, MS, RD, LDN, BC-ADM, CDE of the Kovler Diabetes Center in Chicago and an EndocrineWeb advisor. “Until there are large scale studies that can prove otherwise, it should not be recommended for this at all.”
“Based on the marijuana users I see in clinical practice, they all state they experience "the munchies" and tend to overeat junk food (or anything in sight). The unabashed eating could contribute to the increased visceral fat. And for the young adults I work with who use marijuana, we have long conversations about how it affects cognitive function,” she adds. “They may not take their insulin correctly or take too much. Being high could also mask low blood sugar symptoms and the person could have a very severe and dangerous low.”