Diurnal variations of blood glucose by continuous blood glucose monitoring in peritoneal dialysis patients with diabetes.

Exaggerated postprandial increase in blood glucose has been postulated to be associated with cardiovascular injury. The concentration of blood glucose is altered by glucose absorption from peritoneal dialysis (PD) fluids. In PD patients, we used continuous blood glucose monitoring (CGM) to analyze diurnal variations in blood glucose. Diurnal blood glucose was determined in 10 diabetic PD patients who used CGM (iPro2: Medtronic, Northridge, CA, U.S.A.) for 3 days. Blood glucose concentrations before and after glycemic control were monitored in 5 patients. Correlations between CGM parameters [standard deviation of blood glucose (SDG)], peritoneal function [dialysate-to-plasma ratio of creatinine (D/P Cr) and end-to-initial dialysate (D/D0) glucose], 24-hour peritoneal glucose absorption, and glycemic index were determined. In 5 patients, CGM was performed again after adjustments to antidiabetic drugs. A large diurnal variation, especially at night, was observed in this patient cohort. No correlation of HbA1c with mean blood glucose concentration was observed. Although SDG had no association with 24-hour peritoneal glucose absorption, it did show an association with D/P Cr and D/D0 glucose. The SDG was significantly lower after treatment with a dipeptidyl peptidase IV inhibitor or an increase in insulin dose. Results of the present study indicate that diurnal variations in glucose depend on the speed of peritoneal glucose absorption rather than the net glucose absorption.

Beneficial role of tolvaptan in the control of body fluids without reductions in residual renal function in patients undergoing peritoneal dialysis.

The V2 receptor antagonist tolvaptan has been approved for volume control in heart-failure patients in Japan. Tolvaptan increases renal blood flow, and so the present study was designed to ascertain whether tolvaptan could be a useful diuretic for volume control without reducing residual renal function (RRF) in peritoneal dialysis (PD) patients. Tolvaptan was administered in 15 PD patients (15 mg daily). Urine volume, body weight, and blood pressure were monitored Urinary excretion of urea nitrogen Na+, the osmolality of plasma and urine, and peritoneal and renal Kt/V were analyzed before and after tolvaptan treatment. In 11 of 15 patients, urine volume increased to more than 400 mL daily. A significant increase in diluted urine was observed, as indicated by a reduction in the specific gravity or osmolality of urine (or both). Urinary excretion of urea nitrogen, and Na+ was significantly increased Increases in renal Kt/V were observed, but peritoneal Kt/V was unchanged. Singnificant increase in creatinine clearance was also observed These data suggest that tolvaptan not only stimulates water diuresis, but also natriuresis, without reducing RRF in PD patients. Hence, tolvaptan could be a beneficial tool for the control of body fluid and maintenance of RRF in PD patients.