Effects of Aerobic Exercise on Microalbuminuria and Enzymuria in Type 2 Diabetic Patients

Abstract

Increased urinary albumin excretion is a strong predictor for the development of overt diabetic nephropathy and overall cardiovascular morbidity and mortality in patients with type 2 diabetes. In a previous study, regular aerobic physical activity in overweight/obese patients with type 2 diabetes mellitus was found to have significant beneficial effects on glycemic control, insulin resistance, cardiovascular risk factors, and oxidative stress. The aim of the present study was to investigate the effects of aerobic exercise in the same cohort of type 2 diabetic patients on urinary albumin excretion, serum levels and urinary excretion of enzymes, tubular damage, and metabolic control markers in type 2 diabetic patients. Changes from baseline to 3 and 6 months of aerobic exercise were assessed for urinary albumin excretion, serum activities, and urinary excretion of N-acetyl-beta-D-glucosaminidase (NAGA), plasma cell glycoprotein 1 (PC-1) and aminopeptidase N (APN), as well as their association with insulin resistance, cardiovascular risk factors, and oxidative stress parameters in 30 male type 2 diabetic patients (aged 54.8 +/- 7.3 years, with a mean BMI of 30.8 +/- 3.0 kg/m2). Microalbuminuria was found in six (20%) diabetic patients at baseline, three of them (10%) after three months, and only one patient (3.33%) at the end of the study period. A significant correlation was found for urinary albumin excretion at baseline both with sulfhydryl-groups and catalase, but not for urinary albumin excretion with MDA and glutathione. The prevalence of microalbuminuria tended to decrease after six months of aerobic exercise in type 2 diabetic patients, independently of any improvement in insulin resistance and oxidative stress parameters. Neither between-group nor within-group changes were found for urinary PC-1, APN, and NAGA activity. Serum NAGA was significantly increased (p< 0.05) over the control level in diabetic patients at baseline, but it decreased to the normal level after six months of exercise. This study has shown that a six-month aerobic exercise, without any change in the medication, tended to decrease microalbuminuria without changing enzymuria. However, further studies are needed not only to confirm those findings, but to elucidate potential mechanisms that would clarify the beneficial effects of exercise.

Evidence-based risk assessment and recommendations for physical activity clearance: diabetes mellitus and related comorbidities1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process.

“…We found no evidence that PA participation worsens resting proteinuria in persons with type 1 or type 2 diabetes (Garg et al 1995;Groop et al 1990). Despite hypothetical adverse effects of increased proteinuria immediately after exercise, existing data show no progression of nephropathy with exercise and, in fact, increasing PA may decrease existing albuminuria (a type of proteinuria) (Fredrickson et al 2004;Lazarevic et al 2007). In cross-sectional studies, increased PA is associated with a decreased risk of developing nephropathy (Kriska et al 1991;Wadén et al 2008).…”

Beneficial effects of previous exercise training on renal changes in streptozotocin-induced diabetic female rats

“…20,21,40 Moderate exercise also prevented reduction in GFR and attenuated albuminuria in spontaneously hypertensive rats 23 and in diabetic and cardiopathic human. 24,25 Although the mechanisms by which moderate exercise training improves renal function are not fully understood, there are evidences indicating that the better metabolic control, reduction of oxidative stress, and increased production and bioavailability of NO may be involved in this process. 20,21,23,40 In fact, aerobic training during eight weeks induced better metabolic control, reduction of thiobarbituric acid reactive substance (TBARS), and increased NO production, delaying the progression of diabetic nephropathy in STZ-induced diabetic rats.…”

“…Some studies have shown that exercise training of moderate intensity, besides benefiting metabolic control, improves the kidney function, reduces microalbuminuria, restores oxidative balance and increases nitric oxide (NO) bioavailability in STZ-induced diabetic rats, [20][21][22] spontaneously hypertensive rats 23 and humans. 24,25 However, the mechanisms underlying the benefits of exercise on the diabetic kidney are poorly understood, and the evidences for the renal effects of previous exercise training in diabetic females are limited.…”

Tissue Storage of Dipeptides as Protein Guards Against Oxidative Injury in Patients with Type 2 Diabetes and Its Microvascular Complications

“…Carnosines are secreted into the circulation by skeletal muscle cells during physical exercise, which is in line with the beneficial effects of physical exercise on diabetic complications [17,18]. Our recent study shows that the kidney has its own carnosine metabolism [19].…”