Insulin resistance is associated with digital ulcer in patients with systemic sclerosis

To investigate the relationship between insulin resistance and digital ulcers (DUs) in patients with systemic sclerosis (SSc).

Using a cross-sectional design, we recruited 73 consecutive female patients with SSc and 109 sex- and age-matched healthy controls in South Korea from July 2014 to June 2015. The magnitude of insulin resistance was measured using the homeostatic model assessment of insulin resistance (HOMA-IR). DUs ever included active and healed DUs and the extent of skin fibrosis was evaluated using the modified Rodnan skin score (MRSS).

The HOMA-IR in patients with SSc was significantly higher than that in healthy controls (median 1.18 vs. 0.71, p<0.001). In SSc patients, 7 (9.6%) had active DUs and 14 subjects (19.2%) had healed DUs; thus, DUs ever were observed in 21 cases (28.8%). SSc patients with DUs ever had significantly higher HOMA-IR and MRSS compared with those without this feature (median, 2.05 vs. 0.99, p=0.001 and 14 vs. 9.5, p=0.011, respectively). After adjustment for confounding factors using multivariable logistic regression analyses, the HOMA-IR showed a significant positive association with the presence of DUs ever in patients with SSc (OR=1.43, 95% CI=1.01-2.05, p=0.048). In addition, higher MRSS was significantly correlated with DUs ever (OR=1.11, 95% CI=1.02-1.21, p=0.015).

Insulin resistance was independently associated with the presence of DUs in patients with SSc and may be a potential biomarker for SSc micro-vasculopathy. Moreover, our data also suggest a potential contribution of insulin resistance to the pathogenesis of DUs.