Pot Smoking May Increase Prediabetes Risk

Marijuana use in early adulthood was associated with an increased risk for prediabetes, but not diabetes, by middle adulthood in an adjusted analysis of data from the Coronary Artery Risk Development in Young Adults (CARDIA) study.

Current marijuana use was associated with a 65% increase in prediabetes risk and very frequent use (≥100 uses) was associated with a 49% increase in risk, researcher Michael P. Bancks, MPH, of the University of Minnesota, in Minneapolis, and colleagues wrote in the journal Diabetologia.

Previous Studies Suggest Metabolic Benefit

The findings appear to contradict those of many previous studies, which suggest an overall beneficial effect on metabolic risk associated with marijuana use.

In a recent meta-analysis of eight studies, current marijuana use was found to be associated with a significant decrease in diabetes risk. And cannabis was associated with lower body weight in a study published in August. Those researchers concluded that this may explain the perceived beneficial impact on metabolic risk.

In an email exchange with MedPage Today, Bancks wrote that the objective measurement of prediabetes and diabetes status in the CARDIA study using multiple metabolic measures was a novel strength of the newly published study, along with the prospective and concomitant assessment of the association between marijuana and diabetes and prediabetes.

"While marijuana use was assessed by self-report, which is a potential limitation, our marijuana use response rates were similar to those noted in young adults in the general U.S. population," he said.

Third Decade of Follow-Up

All participants in the CARDIA study were ages 18 to 30 at recruitment between 1985 and 1986, and they have just reached their third decade of observation.

For the newly published analysis, the association between marijuana and prevalence of prediabetes and diabetes was examined in 3,034 participants at CARDIA exam year 25 (2010–2011) and incidence of prediabetes and diabetes according to previous marijuana use was assessed in 3,151 participants without prediabetes and diabetes at year seven (1992–1993) who returned for at least one of the four subsequent follow-up examinations over the next 18 years.

Current marijuana use among the included participants declined during follow up, from 28% in 1985 to just 12% in 2010-2011.

After adjustment for behavioural/lifestyle and physiological characteristics, the researchers reported a 65% increased odds of currently having prediabetes in participants who reported current use of marijuana, and a 49% increased odds of currently having prediabetes in those who reported lifetime use of 100 times or more, compared to individuals who reported never using marijuana.