Does dietary protein intake correlate with markers suggestive of early diabetic nephropathy in children and adolescents with Type 1 diabetes mellitus?

Aims To examine the relationship between dietary protein intake and possibl e early markers of diabetic nephropathy (creatinine clearance (CrCl), kidne y volume and albumin excretion rate (AER)). Methods One hundred and forty-five subjects with diabetes for 5-10 years, d ivided into three pubertal groups, participated. Kidney volume was measured by ultrasound, and serum creatinine and HbA(1c) were assayed. Two or three 24-h urine collections were obtained for albumin, creatinine and urea excr etion rates. Dietary protein intake was estimated from urinary urea nitroge n excretion rate. Glomerular filtration rate was estimated by creatinine cl earance. Results Mean protein intake was 1.22 +/- 0.48 g.kg(-1).day(-1) Protein inta ke was significantly higher in males than females (P < 0.0001) and highest in pre-pubertal compared to mid-pubertal and post-pubertal subjects (P < 0. 001). In multiple regression analysis, protein intake was positively associ ated with CrCl (P < 0.0001), and male sex (P < 0.0001) and negatively assoc iated with body surface area (P = 0.0013) and age (P = 0.01). Kidney volume and AER were not related to dietary protein intake. Conclusions This cross-sectional study failed to show a significant relatio nship between dietary protein intake and markers of early nephropathy, othe r than CrCl. However, a longitudinal, prospective study is required to defi nitively assess the role of protein intake in the evolution of diabetic nep hropathy.