PURPOSE: Although it is widely recognized that type II diabetes (DM) is associated with diastolic dysfunction (DD), and despite increasing evidence that diabetic lung disease is more prevalent than generally recognized, it is unknown which one of these factors contributes more to dyspnea in diabetic patients.
METHODS: We reviewed medical records for all adult patients presenting with dyspnea and undergoing pulmonary function testing (PFT) and echocardiograms in our institution between 1/2004-12/2005. In a cross-sectional analysis we used multivariable logistic regression to examine the association between DM and different ventilatory patterns. We defined restrictive pattern (RE) as FVC < 80% and FEV1/ FVC ≥ 70% and obstructive pattern (OB) as FEV1 < 80% and FEV1/ FVC < 70% of predicted values. Further, we selected all patients with DM who had undergone both PFT and echocardiogram and we assessed the prevalence of RE and OB patterns and the presence of diastolic and systolic dysfunction.
RESULTS: Among 613 patients with dyspnea undergoing PFT, 288 (47%) had normal (NL), 214 (35%) had OB and 111 patients (18%) had RE ventilatory pattern (Table 1). There were more diabetics in the RE than in the NL and OB groups (43% vs. 17% vs. 19%). After adjustment for age, BMI, gender, ethnicity and smoking, RE pattern was independently associated with DM (OR 3.5, 95% CI 1.85-6.62), while OB pattern was not (OR 0.77, 95% CI 0.35-1.66). Among 152 diabetics presenting with dyspnea in our study, 60 (39%) had RE only, 20 (13%) had DD only, 30 (20%) had both RE and DD, while the rest had either NL (20%) or OB (8%) ventilatory pattern.
CONCLUSION: Restrictive ventilatory pattern is independently associated with diabetes. Dyspnea in diabetic patients is due to restrictive ventilatory pattern rather than diastolic dysfunction.
CLINICAL IMPLICATIONS: In the new era of inhaled insulin, a better understanding of lung dysfunction in diabetics is needed in order to differentiate between lung toxicity due to chronic hyperglycemia and the potential side effects of inhaled insulin.
DISCLOSURE: Oana Klein, No Financial Disclosure Information; No Product/Research Disclosure Information