Glucose intolerance in chronic respiratory failure.

A 75-g oral glucose tolerance test (OGTT) was performed on 18 patients with chronic respiratory failure and without fasting hyperglycemia, positive urine glucose, or hepatic/pancreatic disorders. Underlying diseases in these patients were pulmonary emphysema (11 cases, 61%), pulmonary tuberculosis (5 cases, 28%), and chronic bronchial asthma (2 cases, 11%). The body mass index (mean +/- SD, 17.6 +/- 2.2 kg/m2, P < 0.001) in these patients was significantly lower than that (23.8 +/- 3.1 kg/m2) in normal subjects. The OGTT results showed an impaired glucose tolerance pattern in 9 cases (50%) and a diabetes mellitus pattern in 6 cases (34%). The mean two-hour plasma glucose value in the patients was 9.8 mmol/L. However, insulin secretion responded well to glucose loading. These results suggest that a high proportion of chronic respiratory failure patients may have an intolerance for glucose loading but a normal insulin secretion pattern.