Insulin Improves Alveolar-Capillary Membrane Gas Conductance in Type 2 Diabetes

Insulin Improves Alveolar-Capillary Membrane Gas Conductance in Type 2 Diabetes Marco Guazzi , MD, PHD , Iacopo Oreglia , MD and Maurizio D. Guazzi , MD, PHD From the Institute of Cardiology, University of Milan, Milan, Italy Abstract OBJECTIVE —In type 1 diabetes, lung diffusing capacity for carbon monoxide (DL CO ) may be impaired, and insulin has been shown to be beneficial in cases in which near-normal metabolic control is achieved. An influence of insulin, per se, on the alveolar-capillary membrane conductance is unexplored. We aimed at testing this possibility. RESEARCH DESIGN AND METHODS —We studied 19 life-long nonsmoking, asymptomatic patients with type 2 diabetes and normal cardiac function, whose GHb averaged 6.2 ± 0.3% with diet and hypoglycemic drugs. DL CO and its subcomponents (alveolar capillary membrane conductance [D M ] and pulmonary capillary blood volume available for gas exchange [Vc]), vital capacity (VC), forced expiratory volume 1 s (FEV 1 ), cardiac output (CO), ejection fraction (EF), pulmonary wedge pressure (WPP), and pulmonary arteriolar resistance (PAR) were determined before and within 60 min after infusion of 50 ml saline + 10 IU of regular insulin or after saline alone on 2 consecutive days (random block design). Glycemia was kept at baseline levels during experiments by dextrose infusion. RESULTS —Percent of normal predicted DL CO averaged 84.2 ± 7.9% and in 14 patients was