One of the most worrisome trends in American public health today is the rapidly rising prevalence of type 2 diabetes, also known as diabetes mellitus. By 2050, over 48 million Americans are expected to be suffering from this debilitating and costly malady, which can greatly complicate other health problems.
Thus, in the national rush to reconsider cannabis laws, it is of nontrivial importance to pause and consider what effect increased cannabis use may have on diabetes.
The connection may not be immediately obvious, but weighs large in the cost/benefit analysis of legalization. As Caulkins et al point out in Marijuana Legalization: What Everyone Needs to Know, the potentially most dramatic consequences of liberalized cannabis policy will probably not result directly from any increases or decreases in marijuana use among any particular cohort of the population; rather, the most wide-reaching effects will probably result indirectly from outside variables somehow connected to cannabis use. For example, because the negative health effects of smoking tobacco are so much greater than those of smoking cannabis, the unanswered question of whether legal weed will decrease (by substitution) or increase (by the rolling of spliffs) the total US consumption of tobacco will matter much more than the question of whether pot smoking itself will go up or down. The same is true of marijuana’s ill-understood relationship with alcohol. Thus, the mere fact that cannabis is safer than these two legal alternatives does not by itself mean that legalizing would be a good idea.
Such nebulous questions extend even to questions about diabetes, which in terms of sheer medical costs dwarfs any damage to public health marijuana may or may not cause. To follow one hypothesis, if increased cannabis consumption led to higher consumption of fatty, processed, and sugary foods, the public cost of any increase in diabetes which may result from the change of laws could easily exceed whatever benefits legalization may realize. This is why research published this year in the British Medical Journal is so important.
The BMJ article (found here), after controlling for factors like level of physical activity, race, and family history, found that heavy cannabis users had a significantly lower prevalence of type 2 diabetes than non-users. This is significant, because the UCLA team which conducted the study note the tendency of heavy cannabis users to eat more junk food. Nevertheless, the group which smoked the most pot had lower BMIs and risk of type-2 diabetes than the other groups.
It should be noted that studies of this kind do not necessarily prove a causal effect – merely a correlation in the general population which suggests some kind of connection between marijuana use and lowered risk of diabetes. The study’s authors admit this limitation and advocate for controlled laboratory studies to learn more about the connection. Nevertheless, the research could have profound implications for the broader legalization debate: if cheap and easy availability to marijuana could help to solve the diabetes crisis in America – as this study suggests may be the case – such a benefit could easily outweigh all other considerations.