No evidence of an exaggerated albuminuric response to physical exercise innon-diabetic siblings of type 1 diabetic patients with diabetic nephropathy

Substantial evidence suggests a role for genetic factors in the development of diabetic nephropathy in both type 1 and type 2 diabetes. In support of this view, non-diabetic relatives of type 2 diabetic patients with nephropa thy have been found to display abnormalities of urinary albumin excretion r ate (AER) both when measured at rest and during physical exercise. The aim of the present study was to assess the albuminuric response to physical exe rcise in non-diabetic relatives of type 1 diabetic patients with nephropath y. AER was measured from urine collections performed (i) overnight, (ii) du ring an oral glucose tolerance test (OGTT), and (iii) during a submaximal b icycle ergometer test in 21 and 24 non-diabetic siblings of type 1 diabetic patients with (DN+; AER >200 mug/min) and without diabetic nephropathy (DN -; AER <20 <mu>g/min). No difference was found in AER (median [range]) meas ured overnight (DN+ vs DN-: 3.8 [1.3-24.1] vs 3.5 [2.0-21.0] mug/min; P=NS) , during the OGTT (DN+ vs DN-: 6.3 [3.2-26.0] vs 4.8 [1.9-15.7] mug/min; P= NS) or during the exercise test (DN+ vs DN-: 44.8 [7.0 - 535] vs 30.0 [3.4- 1614] mug/min; P = NS). In conclusion, we found no evidence of an exaggerat ed albuminuric response to physical exercise in non-diabetic relatives of t ype 1 diabetic patients with nephropathy. This differs from previous findin gs in type 2 diabetes and may suggest differences in the mode of inheritanc e of albuminuria between type 1 and type 2 diabetes.