Ion- and osmoregulating renal functions in patients with type 2 diabetes mellitus

Aim.

The study of ion- and osmoregulating renal functions in patients with type 2 diabetes mellitus (T2DM) for individual predictive assessment of renal response to exenatide treatment.

Materials and methods.

In total, 41 patients with T2DM were included in the study (12 males, 29 females). Compensated and subcompensated heart failure was observed in 80% and 20% of the patients, respectively. Nephropathy in the microalbuminuria stage was diagnosed in 34% of these patients. The patients’ ages ranged from 34 to 82 years. The mean duration of T2DM was 7 ± 1 years. The mean value of glycated haemoglobin was 8.1 ± 0.4 mmol/l. The control group included 16 healthy women, aged 24‒36 years. Ion- and osmoregulating renal functions and glycaemia levels were assessed after water loading and exenatide treatment (5 µg). Blood serum and urine osmolalities were measured using a micro-osmometer (Advanced Instruments 3300). Capillary blood glucose concentrations were determined using a test system (Accu-Chek Go). Serum and urine levels of urea, protein, creatinine, cholesterol, triglycerides, HDL, LDL, alanine aminotransferase and aspartate aminotransferase as well as cations were determined on a biochemical analyser (Erba XL-200 and Architect c8000), flame photometer (Sherwood-420) and atomic absorption spectrophotometer (Shimadzu AA-6200).

Results.

Reabsorption of solute-free water on the background of endogenous vasopressin action was not disturbed in patients with T2DM. An increase in solute free water clearance in response to water load occurred in healthy subjects as well as in patients with T2DM. After exenatide administration, a correlation between the changes in urinary sodium excretion and blood glucose levels was found (p <0.01). The increase in diuresis in oedema exenatide-treated patients was attributed to the rise of renal sodium excretion; there is a strong correlation between values of sodium excretion during the control period and after exenatide injection (p <0.001).

Conclusions.

The results indicate the prognostic significance of initial kidney function to assess the capacity for removal of water and ions and the subsequent reactions to exenatide.

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