Physical exercise aids glycemic control and the prevention of diabetes-related complications. However, exercise beyond an individual's pulmonary functional capacity may be detrimental. To date, ...little is known about the relationship between pulmonary function and exercise capacity in people with type 2 diabetes (T2D). We investigated the relationship between pulmonary function and exercise capacity in T2D.
Spirometry and 6-min walk test (6MWT) were conducted for 263 systematically sampled adults with T2D without primary heart/lung disease. The primary measure of exercise capacity was the 6-min walk distance (6MWD); impaired exercise capacity was defined as 6MWD<400 m. Logistic regression analyses were used to assess the associations between spirometric measures and exercise capacity with adjustments for age, sex, height, body mass index, diabetes duration, glycated hemoglobin concentration, smoking, suboptimum blood pressure control, and total cholesterol concentration.
Compared with individuals with normal spirometry, those with pulmonary restriction/obstruction had significantly lower 6MWD (404.67 m vs. 451.70),p < 0.001). The proportion of individuals with impaired exercise capacity was higher in individuals with impaired pulmonary function compared with those with normal pulmonary function (39.8% vs. 20.7%,p = 0.001). In the unadjusted models, decreasing Z-score FEV1 odds ratio 1.40, 95% confidence interval (1.07–1.83),p = 0.013 and Z-score FVC 1.37 (1.06–1.76),0.016, but not Z-score FEV1/FVC ratio 1.00 (0.78–1.27),0.972 were significantly associated with impaired exercise capacity. In the fully adjusted model, the strength of association remained statistically significant for Z-score FEV1 1.60 (1.06–2.41),0.025 but not Z-score FVC 1.48 (0.98–2.23),0.065.
Our study shows inverse associations between FEV1 and impaired exercise capacity in T2D, Future research could characterize optimal exercise levels based on a patient's FEV1.
•Impaired exercise capacity was commoner in patients with type 2 diabetes with lung dysfunction than without lung dysfunction.•Lower forced expiratory volume in 1 s was positively associated with impaired exercise capacity.•The conventional cardiovascular and respiratory risk factors did not explain the observed associations.
Existing reports show a bidirectional association between type 2 diabetes mellitus (T2D) and pulmonary dysfunction. Obesity, which is causally related to both T2D and pulmonary dysfunction, could ...play an important role in this association. However, this has not been reported.
What are the associations of measures of obesity with pulmonary function in T2D?
This was a cross-sectional study among 464 adults with T2D. Spirometry was performed according to the American Thoracic Society/European Respiratory Society guidelines. The predicted values of the spirometric indices were determined using the Global Lung Function Initiative 2012 equations. The values of FEV1/FVC and FVC were used to categorize pulmonary function patterns as normal, obstructive, restrictive, or mixed. Waist circumference (WC) was measured at the midpoint between the lower margin of the lowest palpable rib and the top of the iliac crest.
The mean age, diabetes duration, and female/male ratio of the participants were 55.09 ± 10.45 years, 10.00 ± 7.36 years, and 2.1, respectively. In a multiple linear regression model, WC was a significant predictor of FVC (P = .018) and FEV1/FVC ratio (P = .005), but not FEV1 (P = .472). BMI was a significant predictor of FEV1/FVC ratio (P = .031), but not FEV1 (P = .802) or FVC (P = .129). In a multivariable logistic regression model adjusted for age, sex, socioeconomic status, diabetes duration, glycated hemoglobin, statin use, and smoking pack-years, increasing z score WC was associated with higher odds of restrictive spirometry (OR, 1.32; 95% CI, 1.05-1.66; P = .019), but not airway obstruction (OR, 0.65; 95% CI, 0.42-1.03; P = .067). There were no significant associations of increasing z score BMI with restrictive spirometry (OR, 1.24; 95% CI, 0.98-1.58; P = .075) or airway obstruction (OR, 0.79; 95% CI, 0.51-1.24; P = .305).
Increasing WC is associated with restrictive spirometry, independent of conventional diabetes and pulmonary risk factors. Future research could explore the role of the reversal of central obesity on pulmonary function in T2D.
