Marijuana Smokers Have Better Blood Sugar Control

For ganja lovers, there's good news. A new study suggests that regular marijuana use is associated with favorable indices related to diabetic control.

More specifically, they found that current users had significantly lower fasting insulin and were less likely to be insulin resistant, even after excluding patients who had a diagnosis of diabetes mellitus.

A multicenter research team analyzed data obtained during the National Health and Nutrition Survey (NHANES) between 2005 and 2010. They studied data from 4,657 patients who completed a drug use questionnaire. Of these, 579 were current marijuana users, 1,975 had used marijuana in the past but were not current users, and 2,103 had never inhaled or ingested marijuana. Fasting insulin and glucose were measured via blood samples following a nine hour fast, and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated to evaluate insulin resistance.

Participants who reported using marijuana in the past month had lower levels of fasting insulin and HOMA-IR and higher levels of high-density lipoprotein cholesterol (HDL-C). These associations were weaker among those who reported using marijuana at least once, but not in the past thirty days, suggesting that the impact of marijuana use on insulin and insulin resistance exists during periods of recent use. Current users had 16 percent lower fasting insulin levels than participants who reported never having used marijuana in their lifetimes.

Researchers note that a large waist circumference has been linked to diabetes risk. The study suggests that there were also significant associations between marijuana use and smaller waist circumferences.

"Previous epidemiologic studies have found lower prevalence rates of obesity and diabetes mellitus in marijuana users compared to people who have never used marijuana, suggesting a relationship between cannabinoids and peripheral metabolic processes, but ours is the first study to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance," said lead investigator Murray A. Mittleman, MD, DrPH, of the Cardiovascular Epidemiology Research Unit at the Beth Israel Deaconess Medical Center, Boston.

"It is possible that the inverse association in fasting insulin levels and insulin resistance seen among current marijuana users could be in part due to changes in usage patterns among those with a diagnosis of diabetes (i.e., those with diabetes may have been told to cease smoking). However, after we excluded those subjects with a diagnosis of diabetes mellitus, the associations between marijuana use and insulin levels, HOMA-IR, waist circumference, and HDL-C were similar and remained statistically significant," said Elizabeth Penner, MD, MPH, an author of the study.

And though smoking marijuana can increase appetite, two previous surveys have shown that some daily smokers have a lower body-mass index (BMI).

The investigators acknowledge that data on marijuana use were self-reported and may be subject to underestimation or denial of illicit drug use. However, they point out, underestimation of drug use would likely yield results biased toward observing no association.