A study has identified a link between marijuana use and poor blood sugar control in middle aged people. The research, published in Diabetologia and led by Mike Bancks of the University of Minnesota School of Public Health, found that marijuana use heightens the risk of developing prediabetes which can lead to type two diabetes.

The research found that chronic marijuana use during young adulthood increases the risk of prediabetes in middle age people by up to 40% in a study which assessed 3,000 people over an 18-year period. However, the authors couldn't conclude that there is a link between marijuana use and type two diabetes.

"It is unclear how marijuana use could place an individual at increased risk for prediabetes yet not diabetes," the researchers write in their paper. But they add that the unclear results of the test could be due to the fact that individuals missing from the study could have "generally had higher levels of marijuana use and greater potential for development of diabetes, or that marijuana may have a greater effect on blood sugar control in the prediabetic range than for full-blown type two diabetes," according to the press release.

"In conclusion, marijuana use, by status or lifetime frequency, was not associated with incidence or presence of diabetes after adjustment for potential confounding factors," the authors say. "However, marijuana use was associated with the development and prevalence of prediabetes after adjustment. Specifically, occurrence of prediabetes in middle adulthood was significantly elevated for individuals who reported using marijuana in excess of 100 times by young adulthood."