The research found that current marijuana users had considerably lower fasting insulin and had a lower probability of being insulin resistant, even after excluding patients with diabetes mellitus.
For centuries, people have been using marijuana to improve mood, increase appetite, and alleviate pain. However, a study from earlier this year demonstrated that a pill form of marijuana provides greater pain relief than when a person smokes it.
Approximately 17.4 Americans are current users, and it is estimated that 4.6 million of these users smoke marijuana every day or nearly every day.
A previous report from 2011 showed that marijuana use is on the rise in the U.S., with 6.6% of 12th-graders using it daily.
A synthetic form of its active ingredient, tetrahydrocannabinol, referred to as THC, has already received approval to treat the side effects of chemotherapy, nausea, AIDS-induced anorexia, and other medical problems.
Doctors will start to see more and more marijuana users among their patients due to the recent legalization of recreational marijuana in 2 states and the legalization of marijuana for medical purposes in 19 states and the District of Columbia.
Current users had 16% lower fasting insulin levelsFor the current study, a team of investigators examined data gathered from the National Health and Nutrition Survey (NHANES) between 2005 and 2010.
A total of 4,657 had completed a questionnaire regarding their drug use. Of these subjects, 579 were current marijuana users, 1,975 were not current users but used marijuana in the past, and 2,103 had never used marijuana.
After nine hours of fasting, the participants gave blood samples so that the experts could measure their fasting insulin and glucose. In order to examine insulin resistance, the experts calculated homeostasis model assessment of insulin resistance (HOMA-IR).
Results showed that the volunteers who reported marijuana use in the previous month had reduced levels of fasting insulin and HOMA-IR and increased levels of high-density lipoprotein cholesterol (HDL-C).
These links were not as strong among the subjects who reported marijuana use at least once, but not in the previous month.
This indicates, according to the scientists, the influence of marijuana use on insulin and insulin resistance occurs during spells of recent use.
Current users had 16% lower fasting insulin levels than subjects who never used marijuana, according to the results.
Marijuana use linked to smaller waist circumferenceIt is known that people who have large waist circumferences have an increased risk of diabetes. In this research, there were also notable links 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," explained lead investigator Murray A. Mittleman, MD, DrPH, of the Cardiovascular Epidemiology Research Unit at the Beth Israel Deaconess Medical Center, Boston.
However, Mittleman pointed out, "ours is the first study to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance."
Elizabeth Penner, MD, MPH, author of the report, said:
"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."
Despite the fact that marijuana smokers have greater average caloric intake levels than non-smokers, two prior surveys have demonstrated a link between marijuana use and BMI (body mass index).
"The mechanisms underlying this paradox have not been determined and the impact of regular marijuana use on insulin resistance and cardiometabolic risk factors remains unknown," explained coauthor Hannah Buettner.
The researchers pointed out that the data were self-reported, therefore, the subjects may have underestimated their marijuana use or denied their illicit drug use.
On the other hand, they added, underestimating marijuana use would probably yield results biased toward finding no link.
More basic and clinical research is necessaryEditor-in-Chief Joseph S. Alpert, MD, Professor of Medicine at the University of Arizona College of Medicine, Tucson, said:
"These are indeed remarkable observations that are supported, as the authors note, by basic science experiments that came to similar conclusions.
We desperately need a great deal more basic and clinical research into the short- and long-term effects of marijuana in a variety of clinical settings such as cancer, diabetes, and frailty of the elderly. I would like to call on the NIH and the DEA to collaborate in developing policies to implement solid scientific investigations that would lead to information assisting physicians in the proper use and prescription of THC in its synthetic or herbal form."