Aims/hypothesis
Hydroxychloroquine (HCQ), an antimalarial drug with anti-inflammatory properties, is employed in rheumatic diseases. In observational studies, patients with rheumatic diseases treated with HCQ have a lower risk of developing diabetes. However, the physiological mechanisms remain unexplained. We hypothesised that HCQ may have favourable effects on insulin sensitivity and/or beta cell function.
Methods
This was a randomised, double-blind, parallel-arm (placebo vs HCQ 400 mg/day) trial at the University of Pittsburgh. Randomisation was conducted by a computer system with concealment by sealed envelopes. Treatment duration was 13 ± 1 weeks. Randomised participants (HCQ n = 17; placebo n = 15) were non-diabetic volunteers, age >18, overweight or obese, with one or more markers of insulin resistance. All participants were included in intention-to-treat analysis. Outcomes were changes in insulin sensitivity and beta cell function measured by intravenous glucose tolerance tests and minimal model analysis.
Results
There was a positive change in insulin sensitivity with HCQ but not placebo (mean ± SEM: +20.0% ± 7.1% vs −18.4% ± 7.9%, respectively; p < 0.01; difference: 38.3% ± 10.6%; 95% CI: 17%, 60%). Improvement in beta cell function was also observed with HCQ but not placebo (+45.4% ± 12.3% vs −19.7% ± 13.6%; p < 0.01; difference: 65% ± 19%; 95% CI: 27%, 103%). There were modest treatment effects on fasting plasma glucose and HbA1c (p < 0.05) but circulating markers of inflammation (IL-6, IL-1, TNF-α, soluble intercellular adhesion molecule) were not affected in either group. In contrast, adiponectin levels increased after HCQ treatment but not after placebo (+18.7% vs +0.7%, respectively; p < 0.001). Both low- and high-molecular-weight adiponectin forms accounted for the increase. There were no serious or unexpected adverse effects.
Conclusions/interpretation
HCQ improves both beta cell function and insulin sensitivity in non-diabetic individuals. These metabolic effects may explain why HCQ treatment is associated with a lower risk of type 2 diabetes. An additional novel observation is that HCQ improves adiponectin levels, possibly being a mediator of the favourable effects on glucose metabolism. Our findings suggest that HCQ is a drug with considerable metabolic effects that warrant further exploration in disorders of glucose metabolism.
Trial registration Clinicaltrials.gov NCT01326533
Funding This study was funded by National Institutes of Health no. 5R21DK082878, UL1-RR024153 and UL-1TR000005.