Significant association of poor glycemic control with increased resistance in efferent arterioles - Study of inulin and para-aminohippuric acid clearance in humans

Aims: To examine whether glomerular hemodynamic parameters in humans are associated with glycemic control indices, by simultaneously measuring clearance of inulin (C-in) and para-aminohippuric acid (C-PHA). Methods: Thirty-one subjects (age 55.4 +/- 14.7 years; 15 men and 16 women; 21 diabetics and 10 non-diabetics) were enrolled. C-in and C-PAH were measured simultaneously. Afferent arteriolar resistance (R-a), efferent arteriolar resistance (R-e), glomerular hydrostatic pressure (P-glo) and glomerular filtration fraction (FF) were calculated according to Gomez' formula. Results: FF correlated significantly and positively with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c) and glycated albumin (GA) (r = 0.396, p = 0.0303; r = 0.587, p = 0.0007; r = 0.525, p = 0.0070, respectively). P-glo correlated significantly and positively with FPG, HbA1c and GA (r = 0.572, p = 0.0008; r = 0.535, p = 0.0019; r = 0.540, p = 0.0053, respectively). Although there was no significant correlation between R-a and glycemic control indices, R-e correlated significantly and positively with HbA1c and GA (r = 0.499, p = 0.0043; r = 0.592, p = 0.0018, respectively). FF, P-glo and R-e were associated significantly with HbA1c and GA after adjustment for age. Conclusions: These results demonstrate, in humans, that poor glycemic control is associated with increased R-e, but not R-a. It is suggested that increased R-e causes increased P-glo, leading to increased FF. Thus, hemodynamic abnormalities with poor glycemic control may be related to glomerular hypertension in humans. (C) 2014 Elsevier Ireland Ltd. All rights reserved.