Cannabis may prevent development of type 2 diabetes
Murray Mittleman, of the Cardiovascular Epidemiology Research Unit at the Beth Israel Deaconess Medical Centre in Boston, analysed data on almost 5,000 patients who were quizzed about their use of recreational drugs as part of the National Health and Nutrition Survey between 2005 and 2010.
They found that 2,103 had never use cannabis, 975 had used the drug in the past but were not current users, and 579 (over 10%) had inhaled or ingested it in the past month.
Tests showed that current users had 16% lower fasting insulin levels and reduced insulin resistance than those who had never used cannabis . Non-users also had larger waistlines and lower levels of high-density lipoprotein (HDL or 'good') cholesterol - both of which are risk factors for type 2 diabetes.
The same benefits were seen among participants who had used the drug in the past but the associations were not as strong, indicating that the effects of cannabis use on insulin levels and insulin sensitivity wear off over time.
"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 to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance," said lead investigator Mittleman.
Prof Joseph S. Alpert, of the University of Arizona College of Medicine, and editor in chief of the American Journal of Medicine, which published the findings, said: "These are remarkable observations that are supported 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."
In the United States, 19 states have legalised cannabis for medicinal purposes by patients with one of several conditions including multiple sclerosis and cancer, while recreational use of the drug is now legal in two states (Colorado and Washington).
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