Limitations, yet biologically plausible
The researchers acknowledged several study limitations.
They do not know how long participants had used marijuana. The men and women may have underreported their cannabis use, especially in states where medical marijuana was not legal, and the NHANES data did not specify whether the cannabis was recreational or medicinal.
The study may have been underpowered to detect a smaller difference in men who used versus did not use marijuana.
And importantly, this was an observational study (a snapshot at one point in time), so it cannot say whether the heavy cannabis use in women caused a decreased likelihood of diabetes.
Nevertheless, the inverse association between cannabis use and presence of type 2 diabetes is biologically plausible, Dr. Ogunsola and colleagues wrote.
The two major cannabis compounds, cannabidiol and delta-9-tetrahydrocannabinol, stimulate CBD1 and CBD2 receptors in the central and peripheral nervous systems, respectively. And “activation of the CBD1 receptor increases insulin secretion, glucagon, and somatostatin, and activates metabolic processes in fat and skeletal muscles – mechanisms that improve glucose disposal,” they explained.
The researchers speculated that the sex differences they found for this association may be caused by differences in sex hormones, or the endocannabinoid system, or fat deposits.
Therefore, “additional studies are needed to investigate the sex-based heterogeneity reported in this study and to elucidate potential mechanisms for the observation,” they concluded.
The study did not receive any funding and the researchers have no relevant financial disclosures.
A version of this article first appeared on Medscape.com.