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Context: The insulin-stimulating and glucagon-regulating effects of the 2 incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), contribute to maintain normal glucose homeostasis. Impaired glucose tolerance occurs with high prevalence among patients with end-stage renal disease (ESRD)., Objective: To evaluate the effect of the incretin hormones on endocrine pancreatic function in patients with ESRD., Design and Setting: Twelve ESRD patients on chronic hemodialysis and 12 matched healthy controls, all with normal oral glucose tolerance test, were included. On 3 separate days, a 2-hour euglycemic clamp followed by a 2-hour hyperglycemic clamp (3 mM above fasting level) was performed with concomitant infusion of GLP-1 (1 pmol/kg/min), GIP (2 pmol/kg/min), or saline administered in a randomized, double-blinded fashion. A 30% lower infusion rate was used in the ESRD group to obtain comparable incretin hormone plasma levels., Results: During clamps, comparable plasma glucose and intact incretin hormone concentrations were achieved. The effect of GLP-1 to increase insulin concentrations relative to placebo levels tended to be lower during euglycemia in ESRD and was significantly reduced during hyperglycemia (50 [8-72]%, P = 0.03). Similarly, the effect of GIP relative to placebo levels tended to be lower during euglycemia in ESRD and was significantly reduced during hyperglycemia (34 [13-50]%, P = 0.005). Glucagon was suppressed in both groups, with controls reaching lower concentrations than ESRD patients., Conclusions: The effect of incretin hormones to increase insulin release is reduced in ESRD, which, together with elevated glucagon levels, could contribute to the high prevalence of impaired glucose tolerance among ESRD patients., (© Endocrine Society 2019. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The aim of our study was to evaluate the diurnal variation in glomerular filtration rate (GFR), and the potential mechanisms responsible for such variations in GFR and albuminuria in diabetic nephropathy., Methods: In three 24-hour urine samples, divided into a night- and daytime portion, diurnal variation in albuminuria (ELISA) was assessed. Furthermore, during recumbency changes in albuminuria, GFR (51Cr-EDTA plasma clearance) and arterial blood pressure (TM2420) from nighttime (00:00 to 05:00 hours) to subsequent daytime (08:00 to 13:00 hours) were examined in 20 type 1 diabetic patients with diabetic nephropathy., Results: The 24-hour urine collections showed an average rise in albuminuria from night- to daytime of 51% (95% CI; 16 to 95; P < 0.01). During recumbency a non-significant rise was recorded from night- to daytime in albuminuria (22%, -8 to 61, P=0.15), simultaneously with an increase in GFR of 9.0% (3.4 to 14.5, P < 0.005) and mean arterial blood pressure (MABP) of 8.0% (4.3 to 11.7, P < 0.0001). No diurnal variation in fractional clearance of albumin was found. Significant associations between MABP and albuminuria were demonstrated during night- (R2=0.50; P < 0.001) and daytime (R2=0.48; P < 0.005). A linear regression analysis between diurnal variations in MABP and GFR showed that an increase in MABP (of 10%) from night- to daytime was associated with a significant increase in GFR (of 8.0%, 0.2 to 4.1, P < 0.02)., Conclusions: Our study revealed diurnal variations in GFR, albuminuria and MABP in diabetic nephropathy, with lowest values during sleep at night. The observed diurnal variation in albuminuria seems to be explained partly by mechanisms related to orthostasis, and partly by the diurnal variation in GFR and serum albumin concentration. The diurnal variation of blood pressure seems to play a role for the diurnal changes in GFR and albuminuria.