Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Marian Ayad, BPharm, PharmD candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences

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Insulin resistance in adults with and without obesity, in current and former marijuana users.

Now that the use of marijuana is becoming legalized in many states, it is important to let your patients with diabetes know how it can affect them.

There has been a vast increase in marijuana use in North America over the past decades among adults. Experimental studies have shown that activating the endocannabinoid system can result in a significant increase in glucose uptake by adipocytes. Previous studies have examined the correlation between marijuana use and markers of insulin resistance (IR), which is more common in patients with obesity. However, mixed results have been reported and more studies are required to determine the association between marijuana use and insulin resistance in adults with obesity. A study published very recently was conducted with an aim to examine this association in adults with different BMI status, and after accounting for duration of marijuana use and time since cessation, if any.

This study examined the relationship between marijuana use with both fasting insulin (FINS) and homeostasis model assessment of insulin resistance (HOMA-IR) in participants with and without overweight/obesity. 129,509 participants ages 18 to 59 were included in the study and of the participants included, 32.7% had overweight and 32.6% had obesity. The median plasma FINS concentration was higher in adults that never use marijuana compared with adults who are current users (9.83 μU/mL vs. 7.70 μU/mL). In adults who used marijuana in the past, FINS concentrations were higher with last time use 12-120 months ago compared with those who used it less than 12 months ago. Furthermore, no association with marijuana use with FINS was shown in adults without obesity except in adults who formerly used marijuana < 4 times/month and with the last use 12-120 months ago, where the mean FINS was 37% lower than those who never used marijuana. In participants with obesity, the mean FINS in those who use marijuana < 4 times/month was 52% lower than in people who never use. FINS concentrations were also found to be lower with those who use it more frequently (8 or more uses per month). In participants that had formerly had obesity, FINS concentrations with those who were low users, and those who stopped within 12 months prior, did not differ from those who never used. Those who stopped marijuana use 12 or more months prior had significantly lower FINS concentrations. HOMA-IR association with marijuana was similar to that of FINS.

To sum things up, in adult participants with obesity, the study findings reported an association between using marijuana and significantly lower FINS and HOMA-IR. Current consumers of marijuana had much lower FINS and HOMA-IR than those who never used marijuana before, even at a low frequency of less than 4 uses per month. In addition to that, participants that used marijuana in the past (>10 years ago) also had significantly lower FINS concentrations and HOMA-IR. The study findings also reported that time since cessation of marijuana only affected the outcomes in those who smoked in the past less than 8 times/month. Furthermore, participants who have used marijuana 8 or more times per month in the past, had significantly lower FINS and HOMA-IR compared with participants who have never used, irrespective of time of cessation.

In conclusion, using marijuana chronically, even as low as less than 4 uses/month, is associated with lower FINS and HOMA-IR in adults with obesity, but not in those without obesity. Former users with high lifetime use had lower insulin concentrations compared with adults who never used marijuana, independent of the last time since last use. The authors concluded that further studies are required to take into account both the intensity and timing of marijuana use in relation to FINS and HOMA-IR.

Practice pearls:

Marijuana use was associated with lower fasting insulin (FINS) and homeostasis model assessment (HOMA-IR) in participants with obesity, but not in adults without obesity.

Participants that smoked in the past frequently had significantly lower FINS levels, independent of the last time since last marijuana use.

The study suggests that marijuana use affects FINS and HOMA-IR even at low consumption level and this was confirmed by the finding of lower FINS and HOMA-IR scores after 12 or months in previous marijuana consumers

Ngueta G, Ndjaboue R. Lifetime marijuana use in relation to insulin resistance in lean, overweight, and obese US adults. Journal of Diabetes. 2019;1–10. https://doi.org/10.

1111/1753-0407.12958

Marian Ayad, BSPharm, BCPS, PharmD candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences