Hazard ratios for diabetes ranged from 0.10 to 0.41 among different groupings of patients who took at least 129 g HCQ, according to age, use of glucocorticoids or disease-modifying antirheumatic drugs, and presence of comorbidities.
The investigators noted that “there are substantial differences in the clinical characteristics of SLE patients with and without HCQ use ... [that] may reflect the discrepancy in lupus disease activity between the two groups.” The patients who had used HCQ were significantly older (49 years vs. 37 years) and a greater proportion of them had taken glucocorticoids (92% vs. 73%).
Those who had taken HCQ had significantly lower rates of hyperlipidemia, hypertension, stroke, and renal disease. HCQ users also took more methotrexate, sulfasalazine, and azathioprine, but less cyclophosphamide, than did those without HCQ use.
While the greater use of cyclophosphamide by HCQ nonusers may indicate more frequent lupus renal involvement and potentially bias them to increased risk of diabetes because of disease activity and chronic inflammation’s effect on insulin resistance, the greater cumulative glucocorticoid dose taken by HCQ users also can predispose to the development of diabetes, the authors said.
The study is limited in its ability to tease out the contributions of clinical characteristics between HCQ users and nonusers, because the patients’ lupus disease severity and laboratory data are unknown, and treatment data were recorded only from the first year. There was also a lack of data on lifestyle, body-mass index, and family history, the investigators said.
The study had no specific funding. The authors declared having no conflicts of interest.