New Research Shows How Marijuana Use May Affect Health Later in Adulthood

In one of the studies, researchers tracked marijuana users’ health starting from when they were in their 20s. (Photo: Brett Levin/Flickr)

Marijuana use may increase the risk of high blood sugar during middle age, suggests a new study that contradicts earlier reports.

What little research exists on the topic has found that pot smokers tend to be at lower than average risk of diabetes, so the finding that they may have elevated, so-called pre-diabetic blood sugar levels comes as a surprise, the study authors say.

Prediabetes is “a risk factor for future cardiovascular disease, but if recognized, it is also an intervention point and opportunity to prevent the progression to diabetes and mitigate risk for future cardiovascular disease,” said lead author Mike Bancks, of theUniversity of Minnesota School of Public Health in Minneapolis.

Past studies have found that while marijuana users tend to eat more than non-users, they ended up with characteristics that suggest lower diabetes risk, like healthier weight and smaller waists, the researchers write in Diabetologia.

One such study found that people who used marijuana were 30 percent less likely to develop type 2 diabetes.

But those earlier studies may have been unreliable, the current researchers suggest. For example, results may be skewed if people change their marijuana use over time, based on their health.

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The new research involved two separate analyzes. Like past research, there was no increased risk of full-blown diabetes among marijuana users in either analysis - but there was a higher risk for elevated blood sugar levels.

One analysis involved 3,034 participants in a study that tracked their health and marijuana use since the 1980s, when they were 18 to 30 years old.

Twenty-five years later, in 2010 and 2011, 45 percent of the now middle-aged participants had elevated blood sugar levels.

Those who were current marijuana users were 65 percent more likely to have elevated blood sugar than people who never used the drug. People who reported using marijuana more than 100 times in the past were also more likely to have high blood sugar levels.

The second analysis tracked 3,151 people from the same study who didn’t have high blood sugar in 1992 and 1993. The researchers found a 39 percent increased risk of that problem over the next 18 years among people who reported using marijuana at least 100 times, compared to never-users.

Related: Teenagers Use E-Cigarettes to Vape Marijuana, Study Says

Bancks told Reuters Health in an email that there may be several reasons why they didn’t see an increased risk of diabetes like they did for elevated blood sugar.

For example, excluding participants from the analysis due to missing data may have led to a false finding, he said. Also, marijuana may have more of an impact before diabetesdevelops, rather than afterward.

Dr. Sethu Reddy, who was not involved in the new study, said another reason the researchers may have seen an increased risk of high blood sugar and not diabetes is that participants weren’t followed long enough.

“Maybe in the next five to 10 years they’d have more diabetes,” said Reddy, the chief of the Adult Diabetes Section at the Joslin Diabetes Center in Boston.

The fact that the new results do not fully agree with past research suggests additional studies are needed, said Bancks.

“Our results do not align with the previous research on this topic and this point strongly suggests more research is needed on the metabolic health effects of marijuana use,” he said.

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