Cannabis is the most commonly used illicit substance in North America.1–3 Public perspective about cannabis has changed over years resulting in the legalization of cannabis for medical use followed by recreational use in many states in the United States and recently in all provinces of Canada.4,5
Medical cannabis use refers to the use of cannabis to treat a disease or alleviate symptoms of a chronic medical condition.6 Type 1 diabetes (T1D) is a chronic disease that requires life-long insulin treatment. Cannabis use among patients with T1D is higher than the general population.7 Nearly 18% to 30% adults with T1D are using cannabis either for medical or recreational purposes in the United States.7,8 Patients with T1D use medical cannabis for a variety of reasons including diabetic neuropathy to alleviate pain and diabetic gastropathy to alleviate gastrointestinal symptoms without any constructive evidence.6,7
Cannabis use is generally perceived as safe and on the rise9,10 which is particularly concerning in the setting of a chronic medical illness such as T1D.11 Little is known about the potential negative consequences of cannabis use in the setting of T1D. Having access to one of the largest T1D populations in the United States, we aimed to evaluate problematic cannabis use patterns among recreational and medical cannabis users with T1D.
Adults (≥18 years of age) with T1D attending Barbara Davis Center for Diabetes, one of the largest T1D centers in the United States between June 2017 and January 2018 completed an in-person questionnaire regarding their cannabis use and diabetes management. The relationship between cannabis use and diabetes outcomes from this study were reported previously.8 Cannabis use purpose was self-reported. Cannabis users further self-divided into 2 groups: medical and recreational. Medical cannabis use was defined in the questionnaire as using cannabis with a prescription by a certified healthcare professional. Pregnant patients and patients with diabetes other than T1D were excluded. The Colorado Multiple Institutional Review Board approved the study and all subjects provided written informed consent.
The Cannabis Use Disorder Identification Test-Revised (CUDIT-R) was used to identify the hazardous use of cannabis (score: ≥8 and <12) and possible cannabis use disorder (score ≥12).12 Hazardous use and possible cannabis use disorder categories were together defined as unhealthy cannabis use in our study. CUDIT-R is a screening test for problematic cannabis use and it is a revised version of CUDIT which was a direct modification of the Alcohol Use Disorders Identification Test.12 CUDIT-R questionnaire consists of 8 questions and has a sensitivity of 91% and specificity of 90% for identifying problematic cannabis use.12
Chi-square and 2-sample t tests were used for comparison of categorical variables and normally distributed continuous variables, respectively, between recreational and medical cannabis users. The primary outcomes were to compare the overall mean CUDIT-R score in adults with T1D by cannabis use reason (medical vs recreational) and to assess differences in means within CUDIT-R score categories (nonhazardous use and unhealthy cannabis use) for each use reason after controlling for differences in baseline characteristics. An exploratory outcome was to compare responses to individual CUDIT-R questionnaire questions between recreational and medical groups. Participants with combined cannabis use (medical and recreational) were excluded from the analysis due to inability to define the primary reason for use (n = 16). Difference in overall CUDIT-R score means by use reason and differences in means within the nonhazardous cannabis use and unhealthy cannabis use categories by use reason were assessed using an unpaired t test. P values were considered significant below a 0.05 level.
Out of 631 eligible patients, 449 patients (71.3%) responded to the survey. Age, gender, and diabetes characteristics were similar between responders and nonresponders. Out of 449 responders, 133 patients (30%) reported cannabis use in the last 12 months. Among cannabis users, 85 patients reported recreational use (63.9%), 32 patients (24.1%) medical use, and 16 patients (12%) both. Baseline characteristics of adults with T1D by cannabis use reasons are provided in Table 1. Missing baseline characteristic data were found to be missing completely at random and minimal (<3). Compared to recreational users, medical users were older, had higher income and more likely to be female. Smoking was the most common form of cannabis use in this cohort. Medical users tended to use cannabis more than 4 times a week more frequently than recreational users (59.4% vs 28.2%, P < 0.01). There was no difference between the groups in duration of cannabis use.
Based on CUDIT-R scores, 37.6% of adults with T1D had unhealthy cannabis use (CUDIT-R ≥ 8), which includes hazardous cannabis use (20.5%) and possible cannabis use disorder (17.1%). There was no difference in mean overall CUDIT-R score (7.14 vs 7.5, P = 0.76) between recreational and medical cannabis users. After controlling for baseline characteristics, there were also no significant differences in mean CUDIT-R score between recreational and medical users within the nonhazardous use category (3.70 vs 4.4, P = 0.15) and unhealthy cannabis use category (12.84 vs 12.67, P = 0.92) (Table 2).
Compared to recreational cannabis users, medical cannabis users had a higher mean score for the question assesses the frequency of cannabis use in CUDIT-R questionnaire (2.9 vs 2.2 average scores, P < 0.01). However, this did not change the overall CUDIT-R scores between medical and recreational users.
Cannabis use for medical purposes has been steadily increasing in the state of Colorado in conjunction with legislative changes,7,8 this is of particular concern in the setting of chronic disease, T1D is no exception. Our diabetes center has access to a very large T1D population which has been increasingly exposed to cannabis in different forms recently. We aimed to explore and compare use patterns within a population that unhealthy use definition could apply.
Among unhealthy users with T1D, we found no difference between recreational and medical use categories. We found a higher frequency of use in medical use category, this however could be due to the way medical cannabis prescription was written. Interestingly, despite a higher frequency of cannabis use for medical purposes, CUDIT-R scores were not different among medical and recreational use categories.
There are several limitations of this study. First, CUDIT-R is a screening test to identify the population at risk and we used as a screening method for capturing problematic use of cannabis.13–15 There are 11 diagnostic criteria for substance use disorders in DSM-V which CUDIT-R essentially attempts to screen.16 Ideally, a positive CUDIT-R questionnaire result should follow an addiction evaluation by a clinician for a comprehensive diagnostic assessment to determine whether a valid addictive use pattern exists. Second, our criterion for medical use was limited to reported prescriptions which limited our ability to capture medicinal use without prescription. Third, our T1D population did not have any comparison group which would have allowed us to determine if frequency of use or CUDIT-R severity were higher among T1D.
With the increasing trend of using cannabis in North America, physicians should be aware of the risk of unhealthy cannabis use among patients with T1D. Small sample size, single center, and self-reported cannabis use are limitations of the study. Future research directions should include further understanding the cannabis use patterns in prescribed and nonprescribed users, study designs relying on clinical evaluations for increasing diagnostic validity, randomized control studies focusing on cannabis use in T1D and other chronic diseases.
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