Diaphragm muscle weakness in adults with diabetes

Background: Diabetes–related pulmonary dysfunction, including impaired spirometry and pulmonary gas exchange, is well characterized. However, data on diaphragm muscle weakness(DMW), a predictor of poor clinical outcomes, are limited. Objectives: We report the percentage change in forced vital capacity(FVC) from sitting to supine position(∆FVC), a surrogate measure of DMW, in adults with diabetes. Methods: This cross-sectional study included 537 adults with diabetes without primary pulmonary disease managed at Ghana's National Diabetes Management and Research Centre. Spirometry was conducted sequentially in sitting and supine positions, and ∆FVC was determined. DMW was defined as ∆FVC≥10–20%. Results: The proportions of females and current/previous smokers were 75.0% and 5.2%, respectively. The mean(SD) age, diabetes duration, glycated-hemoglobin, and body-mass-index were 60.77(±10.41)years, 15.90(±9.22)years, 8.66(±1.87)%, and 29.42(±5.92)kg/m2, respectively. Based on ∆FVC regardless of the sitting FVC% predicted, the prevalence of DMW were 20.1%(95%CI:16.7–23.5%), 9.3%(6.9–11.8%), and 6.1%(4.1–8.2%) at ∆FVC cut-off values of 10%,15%, and 20%, respectively. Based on FVC% predicted≤75 and ∆FVC, DMW was present in 9.3%(6.9–11.8%), 3.5%(2.0–5.1%), and 2.6%(1.3–4.0%) at ∆FVC cut-off values of 10%, 15%, and 20%, respectively. In comparison, the prevalence of pulmonary restriction and airway obstruction were 38.2%(34.1–42.3%) and 7.4%(5.2–9.7%), respectively. In individuals with normal spirometry, respectively 20.7%, 11.1%, and 6.6% had DMW using ∆FVC cut-off values of 10%, 15%, and 20%. Conclusion: DMW is prevalent in diabetes, even in individuals with normal conventional spirometry. Future studies could characterize the predictors/clinical consequences of ∆FVC in diabetes, and how this compares with other methods of assessing DMW.