A new study has found that people who had used marijuana in the past month had smaller waists and lower levels of insulin resistance, which is a diabetes precursor, than those who had never tried the drug, according to Reuters.

"These are preliminary findings," Dr. Murray Mittleman, who worked on the study at Beth Israel Deaconess Medical Center in Boston, told Reuters. "It looks like there may be some favorable effects on blood sugar control.

"However, a lot more needs to be done to have definitive answers on the risks and potential benefits of marijuana usage," Mittleman added.

Smoking pot is widely known to cause the "munchies," though previous studies have found that marijuana users tend to weigh less than other people, and one previous study has also suggested they have lower rates of diabetes. Trials in rats and mice have suggested that cannabis and cannabinoid receptors may influence metabolism, which could explain the findings.

The findings are based on surveys and blood tests that were given to about 4,700 U.S. adults. They aren't yet sufficient, however, to prove that marijuana has a positive effect on weight or helps prevent diabetes. Among current pot smokers, there wasn't found to be any additional health benefits from smoking, according to the researchers, who reported their findings in the American Journal of Medicine.

The study used data from a national health survey conducted in 2005-2010, where researchers asked people about their drug and alcohol use, as well as other aspects of their health and lifestyle. They also measured their insulin and blood sugar levels.

People who were current smokers had smaller waists, on average, than those who had never used pot. Users also had a lower body mass index than those who had never used. Even taking other lifestyle factors into account, pot smokers had 17 percent lower insulin resistance and slightly higher HDL (good) cholesterol.

"It's possible that people who choose to smoke marijuana have other characteristics that differ from non-marijuana smokers," and those characteristics are what cause them to have the differences in blood sugar and waist size, making the link causal.

Another possible explanation was provided by Dr. Stephen Sidney from the Kaiser Permanente Division of Research in Oakland, California, who suggests cigarette smoking may explain the association.

"People who use tobacco oftentimes tend to be thinner," Sidney said. "So I really wonder about that."

Dr. Theodore Friedman, who has studied the issue at Charles R. Drew University of Medicine and Science in Los Angeles thinks the link is probably causal. A possibility is that the anti-inflammatory properties of marijuana help ward off diabetes, but more research is needed to draw any firm conclusions.

"I want to make it clear - I'm not advocating marijuana use to prevent diabetes," Friedman said. "It's only an association."