Tags:  Incident Type II diabetes; cannabis use in HIV; longitudinal study

 

Thumbnail: Daily cannabis use was associated with reduced risk of type II diabetes.

 

The problem: Previous studies have suggested that cannabis use can increase the risk for type II diabetes. However, it is not clear whether cannabis use among people living with HIV can increase their risk for developing type II diabetes.

 

The study: The study looked for associations between cannabis use and the development of type II diabetes among women and men who were HIV-positive or were at risk for HIV-infection. The researchers utilized data from the Women’s Interagency HIV Study (WIHS) and Multicenter AIDS Cohort Study (MACS), which are well-established cohorts of men and women who are living with or at risk for HIV in the United States. The study used nearly 20 years of follow-up data from 3578 participants in WIHS (61% were HIV positive) and 2682 in MACS (49% were HIV positive).

 

Main results:

• WIHS cohort: A follow-up between 2000-2017 among women living with or at risk for HIV identified 452 incident cases of type II diabetes.

  • 320/452 cases (~70%) were among HIV-positive women.

    • Unadjusted incidence rate for type II diabetes was 1.46 per 100 person-years among all women in WIHS.

• MACS cohort: A follow-up between 1999-2017 among men at risk for HIV identified 326 incident cases of type II diabetes.

  • 164/326 cases (~50%) cases were among HIV-positive men.

    • Unadjusted incidence rate for type II diabetes was 1.04 per 100 person-years among all men in MACS.

• The data collectively showed a reduced risk for developing type II diabetes among daily cannabis users, compared to non-users.

  • Hazard ratios (HR) for this association were 0.56 and 0.6, in the WIHS and MACS cohorts, respectively.

  • However, the hazard ratios varied widely between daily, weekly or monthly use and not all the associations were statistically significant.

 

Conclusions:  Cannabis use was associated with reduced risk for developing type II diabetes among people living with or at risk for HIV.

 

Why this is a good study:

• This was a ~ 20-year longitudinal study using a large cohort of people who are living with or who are at risk for HIV infections. Such long follow-up studies can reveal many trends that are often missed in short-term studies.

• Unlike previous studies on this topic, the authors have adjusted for potential confounders such as age/race/alcohol use and body mass index.

 

Why this isn’t a perfect study:

• The information on cannabis use was mostly self-reported, which may be associated with underestimates of use. The authors acknowledge that this underreporting can lead to variability in the analyses.  However, in general, underreporting makes it more difficult to detect associations, so any positive findings should be taken seriously.

 

What this study adds:

• Cannabis use can stimulate appetite and therefore, there’s a belief that its use can increase a person’s risk for developing type II diabetes. However, this study shows that daily cannabis use is, in fact, associated with a reduced risk for developing type II diabetes.

• Interestingly, this study shows that cannabis use is dose-dependently associated with both lower BMI and hemoglobin A1C levels.

• The authors explore the concept of reverse causality. In other words, do pre-type II diabetes symptoms lead to reduced cannabis use among people living with HIV? However, these associations were not statistically significant.

 

What it doesn’t:

• The study does not factor in the mode of cannabis use or how much of it was consumed, only whether it was consumed or not and frequency of use. The onset of type II diabetes could also be associated with these factors.

 

Funder:  National Institute of Drug Abuse and National Institute of Mental Health grants.

 

Author conflicts:  None.