If the link is proved, it could lead to the development of treatments based on the active ingredient of cannabis, tetrahydrocannabinol (THC), without its intoxicating effects.
Researchers have found that regular users of the drug had lower levels of the hormone insulin after fasting – a signal that they are protected against diabetes. They also had reduced insulin resistance. Cannabis is widely smoked in the United States with over 17 million current users of whom more than four million smoke it on a daily basis. In the UK latest figures show 2.3 million people used cannabis in the last year, but the numbers have declined in the last decade.
Two US states have recently legalised its recreational use and 19 others have legalised it for medical purposes by patients with one of several conditions including multiple sclerosis and cancer. THC has already been approved to treat the side effects of chemotherapy, nausea in cancer patients, anorexia associated with AIDS and other conditions.
The study involved almost 5,000 patients who answered a questionnaire about their drug use and were part of the National Health and Nutrition Survey between 2005 and 2010. The results showed almost 2,000 had used cannabis at some point in their lives and more than one in 10 (579) were current users. Only those who had used cannabis within the past month showed evidence of protection against diabetes, suggesting that the effects wear off in time. Current users of the drug had 16 per cent lower fasting insulin than those who had never used the drug.
Murray Mittleman, of the Cardiovascular Epidemiology Research Unit at the Beth Israel Deaconess Medical Centre in Boston, and lead author of the study published in The American Journal of Medicine, said previous studies had shown lower rates of obesity and diabetes in marijuana users.
Two previous surveys had also shown that although cannabis users consume more calories they have a lower body mass index. The mechanisms underlying this paradox are unknown, the authors say. Joseph Alpert, professor of medicine at the University of Arizona College of Medicine, Tucson, and editor in chief of the journal, 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.”
Almost one in 20 adults in the UK has diabetes, of which 2.6 million are diagnosed and 500,000 are undiagnosed. Rates are rising in this country and around the world, driven by Western lifestyles, and the number of cases is expected to exceed 4 million in the UK by 2025. The illness increases the risk of heart failure, kidney failure, and death – and is one of the biggest health challenges facing the UK.
By Jeremy Laurance