THE ASSOCIATION BETWEEN DIABETIC COMPLICATIONS AND EXERCISE CAPACITY IN NIDDM PATIENTS

OBJECTIVE - Exercise capacity has been used as a noninvasive parameter for predicting cardiovascular events. It has been demonstrated previo usly in NIDDM patients that several risk factors (i.e., obesity, smoki ng, hypertension, and African-American race) are associated with an im paired exercise capacity. We studied 265 male and 154 female NIDDM pat ients who underwent graded exercise testing with expired gas analyses to determine the possible influences of diabetic neuropathy, nephropat hy, and retinopathy on exercise capacity RESEARCH DESIGN AND METHODS - Univariate and multiple linear regression analyses were performed to determine the relationship between diabetic neuropathy, urinary albumi n excretion (UAE), and retinopathy with respect to peak oxygen consump tion (VO2). Neuropathy was assessed by neurological symptom and disabi lity scores, autonomic function testing, and quantitative sensory exam s involving thermal and vibratory sensation. Three categories of UAE w ere used: normal albuminuria (< 20 mu g/min), microalbuminuria (20-200 mu g/min), and overt albuminuria (> 200 mu g/min). Retinopathy was as sessed by stereoscopic fundus photographs. Multiple linear regression analyses were then performed controlling for age, sex, length of diagn osed diabetes, duration of hypertension, race and ethnicity, GHb, BMI, and smoking to determine whether there was an independent effect of t hese diabetic complications on exercise capacity. RESULTS - Univariate analyses revealed that the presence of diabetic retinopathy (P = 0.03 ), neuropathy (P = 0.002), microalbuminuria (P = 0.04), and overt albu minuria (P = 0.06) were associated with a lower peak VO2. Multiple lin ear regression analyses were performed to determine independent relati onships with peak VO2. The results revealed that increasing retinopath y stage (Parameter estimate [PE] = -0.59 +/- 0.3 ml.kg(-1).min(-1); P = 0.026) and increasing UAE stage (PE = -0.62 +/- 0.3 ml.kg(-1).min(-1 ); P = 0.044) were associated with a decrease in peak VO2. CONCLUSIONS - In the present study of NIDDM subjects, a significant independent a ssociation was demonstrated between diabetic nephropathy and retinopat hy with exercise capacity. These results were obtained controlling for age, sex, length of diagnosed diabetes, hypertension, race, and BMI. Thus the findings in this large NIDDM population without a history of coronary artery disease indicate a potential pathogenic relationship b etween microvascular disease and exercise capacity.