Relationship between fat intake and glomerular filtration rate in normotensive insulin-dependent diabetic patients

Glomerular hyperfiltration is a candidate marker for diabetic nephropathy in insulin-dependent diabetic patients since it can reflect elevated glomerular capillary pressure, a cause of glomerulosclerosis. We studied the potential contribution of several dietary components to glomerular hyperfiltration during a cross-sectional study of 110 consecutive normotensive, non-proteinuric insulin-dependent patients with respect to glomerular filtration rate (GFR) and food intake. GFR was measured using the 51Cr-EDTA plasma disappearance technique. Glomerular hyperfiltration was defined as GFR > 137 ml.min-1 1.73 m-2 (mean +2 SD of age-matched healthy controls). Food intake was recorded with a computer-assisted programme. Thirteen patients displaying glomerular hyperfiltration ingested more protein (1.60 +/- 37 vs 1.38 +/- 0.34 g.kg-1 body weight.day-1; p = 0.032) and more fat (1.70 +/- 0.54 vs 1.39 +/- 0.44 g.kg-1 body weight.day-1; p = 0.022) than other subjects, although their total energy intakes were similar. Univariate regression analysis showed that GFR was positively related to both protein (r = 0.28; p = 0.003) and fat (r = 0.25; p = 0.007) intakes and negatively related to age (r = -0.29; p = 0.002). Stepwise multivariate regression analysis indicated 2 independent determinants for GFR: age (F = 15.26) and fat intake (F = 13.15). Excess fat intake may contribute to glomerular hyperfiltration in insulin-dependent diabetes.