Physical activity and diabetes complications in patients with type 1 diabetes: the Finnish Diabetic Nephropathy (FinnDiane) Study.

Physical activity exerts numerous beneficial health effects, and the evidence favoring a physically active lifestyle in the treatment of chronic diseases is substantial (1). For patients with diabetes, physical activity is considered important (2). In theory, regular physical activity may prevent diabetes complications through beneficial effects on glycemic control, insulin sensitivity, blood pressure, lipid profile, and endothelial function. However, physical activity could also cause adverse effects or patients may not be able to exercise due to complications. Little, however, is known about the relationship between physical activity and diabetes complications (3). Therefore, we investigated the associations between physical activity and microvascular and macrovascular diabetic complications in a large cohort of patients with type 1 diabetes from the Finnish Diabetic Nephropathy (FinnDiane) Study.

The FinnDiane Study and the assessment of self-reported leisure-time physical activity (LTPA) by a questionnaire have previously been described (4). This is a cross-sectional analysis of 1,945 patients with data on LTPA. Renal status was based on at least three urine collections. Renal function was evaluated by the Cockcroft-Gault formula (5) for estimated creatinine clearance. Data on retinopathy and cardiovascular disease (CVD) were obtained from medical records. Differences between groups were …

P hysical activity exerts numerous beneficial health effects, and the evidence favoring a physically active lifestyle in the treatment of chronic diseases is substantial (1). For patients with diabetes, physical activity is considered important (2). In theory, regular physical activity may prevent diabetes complications through beneficial effects on glycemic control, insulin sensitivity, blood pressure, lipid profile, and endothelial function. However, physical activity could also cause adverse effects or patients may not be able to exercise due to complications. Little, however, is known about the relationship between physical activity and diabetes complications (3). Therefore, we investigated the associations between physical activity and microvascular and macrovascular diabetic complications in a large cohort of patients with type 1 diabetes from the Finnish Diabetic Nephropathy (FinnDiane) Study.

RESEARCH DESIGN AND
METHODS -The FinnDiane Study and the assessment of self-reported leisure-time physical activity (LTPA) by a questionnaire have previously been described (4). This is a cross-sectional analysis of 1,945 patients with data on LTPA. Renal status was based on at least three urine collections. Renal function was evaluated by the Cockcroft-Gault formula (5) for estimated creatinine clearance. Data on retinopathy and cardiovascular disease (CVD) were obtained from medical records. Differences between groups were evaluated with the Kruskal-Wallis test for total LTPA; otherwise, the 2 test was used.  Table 1 shows total LTPA, components of LTPA, and previous LTPA habits according to various degrees of diabetes complications. Physical inactivity, as well as low-frequency and low-intensity LTPA, were more common in patients with diabetic nephropathy and proliferative retinopathy than in those without these complications. Patients with microalbuminuria more frequently reported low-intensity LTPA than those with normal urinary albumin excretion rate (P ϭ 0.047 adjusted for age and sex). Impaired renal function and CVD were also associated with low-intensity LTPA.

RESULTS
We further performed multiple logistic regression models controlling for duration of diabetes, sex, and BMI. CONCLUSIONS -Patients with diabetic micro-and macrovascular complications reported different patterns of LTPA compared with patients without complications. The most prominent difference was the intensity of LTPA, since low intensity was clearly associated with impaired renal function and increasing degree of proteinuria, retinopathy, and CVD.
Diabetes complications may limit the patient's ability to exercise by several mechanisms. Patients with proliferative retinopathy are recommended to avoid strenuous activities and Valsalva-like maneuvers because of risk of vitreous hemorrhage (2). CVD is an evident limitation because of possible exercise-induced myocardial ischemia, systolic or diastolic cardiac dysfunction, or ischemia in the lower limbs. Diabetic nephropathy is strongly associated with CVD (6); however, our data support that CVD is not the Data are medians (interquartile range) or percentages. Sedentary: total LTPA Ͻ10 MET h/week. Low-intensity LTPA: very light to light activities, grade 0 -1 out of an intensity scale of 0 -4. Microand macroalbuminuria: urinary albumin excretion rate (UAER) 30 -299 and Ն300 mg/24 h (24-h collections) or 20 -199 and Ն200 g/min (overnight collections), respectively, in at least two of three consecutive urine collections. Normal renal function: Cockcroft-Gaultestimated creatinine clearance Ն90 ml/min per 1.73 m 2 ; mildly impaired, 60 -89 ml/min per 1.73 m 2 ; impaired, 30 -59 ml/min per 1.73 m 2 ; and severely impaired, Ͻ30 ml/min per 1.73 m 2 . Cardiovascular disease: symptomatic coronary heart disease, myocardial infarction, coronary artery procedure (bypass surgery or angioplasty), stroke, limb amputation, or peripheral artery procedure. Diabetic nephropathy: macroalbuminuria, dialysis, or renal transplantation. *P Ͻ 0.05 vs. normal urinary albumin excretion rate. †P Ͻ 0.05 vs. normal renal function. ‡P Ͻ 0.01 vs. none. §P Ͻ 0.01 vs. without CVD. S-Cr, serum creatinine. sole driving force behind reduced LTPA in patients with nephropathy. A decline in renal function, especially when due to diabetic nephropathy (7), is associated with reduced blood hemoglobin concentration as a result of impaired erythropoietin production, which may impair oxygen delivery during exercise. Autonomic neuropathy may cause inadequate responses in heart rate and blood pressure during exercise (8). Peripheral neuropathy and foot ulcers may impair walking and running ability. Diabetes complications, as well as diabetes itself, are further associated with endothelial dysfunction (9,10), which may impair vasodilatation in exercising skeletal muscle tissue. Finally, diabetes complications are associated with depression (11), which may decrease physical activity.
The observed differences in LTPA between patients with various diabetes complications are probably to a large extent due to the abovementioned exerciselimiting factors. However, the difference in LTPA in patients with microalbuminuria compared with a normal urinary albumin excretion rate is a potentially important finding. Microalbuminuria in type 1 diabetes is unlikely to cause exercise intolerance because patients with microalbuminuria usually have normal kidney function. Therefore, it is possible that low LTPA precedes the development of microalbuminuria.
The study includes a large number of patients, and LTPA was assessed by a questionnaire previously validated in a Finnish cohort (12). Objective measurements of LTPA, however, were not performed, and bias due to self-reported LTPA is possible. A limitation is the cross-sectional study design. A longitudinal study design will be needed to provide evidence for the role of physical activity in the development and progression rate of diabetes complications.