Associations between spirometric impairments and microvascular complications in type 2 diabetes: a cross-sectional study

OBJECTIVE: Evidence shows that the conventional cardiometabolic risk factors do not fully explain the burden of microvascular complications in type 2 diabetes (T2D). One potential factor is the impact of pulmonary dysfunction on systemic microvascular injury. We assessed the associations between spirometric impairments and systemic microvascular complications in T2D. DESIGN: Cross-sectional study. SETTING: National Diabetes Management and Research Centre in Ghana. PARTICIPANTS: The study included 464 Ghanaians aged ≥35 years with established diagnosis of T2D without primary myocardial disease or previous/current heart failure. Participants were excluded if they had primary lung disease including asthma or chronic obstructive pulmonary disease. PRIMARY AND SECONDARY OUTCOME MEASURES: The associations of spirometric measures (forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC ratio) with microvascular complications (nephropathy (albumin-creatinine ratio ≥30 mg/g), neuropathy (vibration perception threshold ≥25 V and/or Diabetic Neuropathy Symptom score >1) and retinopathy (based on retinal photography)) were assessed using multivariable logistic regression models with adjustments for age, sex, diabetes duration, glycated haemoglobin concentration, suboptimal blood pressure control, smoking pack years and body mass index. RESULTS: In age and sex-adjusted models, lower Z-score FEV(1) was associated with higher odds of nephropathy (OR 1.55, 95% CI 1.19–2.02, p=0.001) and neuropathy (1.27 (1.01–1.65), 0.038) but not retinopathy (1.22 (0.87–1.70), 0.246). Similar observations were made for the associations of lower Z-score FVC with nephropathy (1.54 (1.19–2.01), 0.001), neuropathy (1.25 (1.01–1.54), 0.037) and retinopathy (1.19 (0.85–1.68), 0.318). In the fully adjusted model, the associations remained significant for only lower Z-score FEV(1) with nephropathy (1.43 (1.09–1.87), 0.011) and neuropathy (1.34 (1.04–1.73), 0.024) and for lower Z-score FVC with nephropathy (1.45 (1.11–1.91), 0.007) and neuropathy (1.32 (1.03–1.69), 0.029). Lower Z-score FEV(1)/FVC ratio was not significantly associated with microvascular complications in age and sex and fully adjusted models. CONCLUSION: Our study shows positive but varying strengths of associations between pulmonary dysfunction and microvascular complications in different circulations. Future studies could explore the mechanisms linking pulmonary dysfunction to microvascular complications in T2D.