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

Abstract Aims To 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 ). Methods Thirty-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. 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). 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. Conclusions These 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.