Patients with alopecia areata show signs of insulin resistance.

Alopecia areata (AA) is an autoimmune disease associated with high levels of proinflammatory cytokines. Since chronic inflammation plays a major role in the pathogenesis of insulin resistance, AA can theoretically increase the risk of diabetes. We sought to investigate this theory by conducting a case-control study. Sixty patients with alopecia areata and 60 healthy volunteers (matched for age, sex, and body mass index) were evaluated. Fasting blood glucose (FBS), C-peptide, plasma insulin, and homeostasis model assessment for insulin resistance (HOMA-IR) were measured for each individual. Plasma levels of insulin [median (interquartile range IQR): 11.22 (7.28-18.15) µIU/ml vs. 4.80 (3.20-9.00), p < 0.0001)], C-peptide [median (IQR): 2.10 (1.61-3.00) ng/ml vs. 1.40 (1.20-1.88), p < 0.0001)] and HOMA-IR [median (IQR): 2.70 (1.58-3.96) µIU/ml vs. 1.01 (0.64-1.98, p < 0.0001)] were significantly higher in patients with AA compared to controls. The differences remained significant even after controlling for age, gender, and BMI. Patients with a more severe disease (alopecia totalis/universalis) had higher levels of insulin [median (IQR): 15.80 (9.68-21.55) vs. 9.30 (5.33-14.40), p = 0.02)] and HOMA-IR [median (IQR): 3.30 (2.20-4.84) vs. 2.15 (1.29-3.52), p = 0.01] compared to those with patchy hair loss. Our data suggest that individuals with AA are at a higher risk of developing insulin resistance. This may be due to common inflammatory pathogenesis or a shared genetic background.