Increased subcutaneous insulin requirements in diabetic patients recently commenced on peritoneal dialysis.

Background: Diabetic patients often have reduced insulin requirements when they progress to renal failure. Since peritoneal dialysis (PD) solution contains glucose, the insulin requirement of these patients often increases after commenced on PD. However, the change in insulin requirement has not been studied systematically.

Methods: We study 60 consecutive patients (32 male) with diabetic nephropathy newly started on PD. Their insulin requirement before and 6 months after initiation of dialysis is compared. Clinical factors affecting insulin requirement are explored.

Results: All patients received a standard 6 l/day dialysis exchange. The mean age was 60.3 +/- 8.9 years. Twelve patients did not require insulin before PD; four of them were started on insulin 6 months after dialysis. The average dosages of insulin 6 months before and after PD were 0.27 +/- 0.28 and 0.37 +/- 0.29 unit/kg/day, respectively (paired t-test, P < 0.001). The increment in dosage was 0.103 +/- 0.216 unit/kg/day. The dosage of insulin requirement correlates with the small solute transport of the peritoneal membrane, as represented by the mass transfer area coefficient (MTAC) of creatinine (r = -0.307, P = 0.017) and haemoglobin level (r = 0.284, P = 0.028), but not with body mass index (BMI). The change in insulin dosage correlates with the number of 2.5% dialysis cycle required per day (r = 0.433, P = 0.001), but not with peritoneal transport status or BMI. In patients who did not receive hypertonic exchange, the dosage of insulin increased by 1.5 +/- 11.1 unit/day. Each extra 2.5% 2 l exchange results in a 7.5 unit/day (95%CI 3.2-11.8, P = 0.001) increase in insulin requirement.

Conclusion: Diabetic patients have a minimal increase in insulin requirement after initiation of PD per se, but the dosage of insulin increased markedly after exposure to hypertonic glucose solution. Our result provides a basis for the dosage adjustment of insulin in diabetic patients newly commenced on PD.