A new study published in the American Journal of Medicine has shown that marijuana use can lower the risk of diabetes and obesity. The study analyzed data collected from a 2005-2010 survey of over 4600 Americans. Of those surveyed, 2,103 had never ingested or inhaled cannabis, 1,975 had used marijuana in the past, and 579 were current users. The study found that current and prior cannabis users had lower fasting insulin levels as well as smaller waist circumferences. Though marijuana users were found to have greater caloric intake levels than non-users, on average they have lower body mass index (BMI). The study suggests that two of our nation's greatest health risks (diabetes and obesity) could potentially be treated by the use of cannabis.
check out this link for an excellent overview of the study
below is a link to the original article from the American Journal of Medicine