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

AimsTo examine whether glomerular hemodynamic parameters in humans are associated with glycemic control indices, by simultaneously measuring clearance of inulin (Cin) and para-aminohippuric acid (CPHA).MethodsThirty-one subjects (age 55.4 ± 14.7 years; 15 men and 16 women; 21 diabetics and 10 non-diabetics) were enrolled. Cin and CPAH were measured simultaneously. Afferent arteriolar resistance (Ra), efferent arteriolar resistance (Re), glomerular hydrostatic pressure (Pglo) and glomerular filtration fraction (FF) were calculated according to Gomez' formula.ResultsFF 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). Pglo 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 Ra and glycemic control indices, Re correlated significantly and positively with HbA1c and GA (r = 0.499, p = 0.0043; r = 0.592, p = 0.0018, respectively). FF, Pglo and Re were associated significantly with HbA1c and GA after adjustment for age.ConclusionsThese results demonstrate, in humans, that poor glycemic control is associated with increased Re, but not Ra. It is suggested that increased Re causes increased Pglo, leading to increased FF. Thus, hemodynamic abnormalities with poor glycemic control may be related to glomerular hypertension in humans.