LEP and chronic obstructive pulmonary disease: The levels of leptin in COPD patients with exacerbation were significantly higher on D1 and still on D15 compared to healthy subjects [33.3 (16.7–45.5)] ng/ml, p < 0.0001 and [15.7 (8.5–26)] ng/ml, p = 0.022 respectively, versus [9.6 (4.5–13.7)] ng/ml).