[Insulin requirement in patients with type 1 diabetes with reduced renal function: human insulin versus analogue insulin].

Introduction: Insulin clearance and the degree of insulin resistance change in type 1 diabetes in patients with reduced kidney function and make it more difficult to achieve good metabolic control. For some years different analogue insulins have become available. Their pharmacological characteristics in renal failure have not as yet been investigated in detail. The aim of the present retrospective study was to determine the insulin dosage in relation to kidney function in patients with type 1 diabetes treated with human or analogue insulin.

Methods: Insulin dosage of 68 patients treated with human insulin and 74 patients treated with analogue insulin was related to the creatinine clearance (calculated with the Cockcroft-Gault formula). In addition, diabetes-related laboratory parameters, the prevalence of hypertension and the kind of antihypertensive therapy were analysed in both groups.

Results: Patients with type 1 diabetes treated with human or analogue insulin have different insulin demands if their renal function is decreased. In analogue-treated patients, insulin dosage significantly decreased with reduced creatinine clearance (r = 0,257; p = 0,026) in contrast to human insulin treated patients who did not show such a decrease (r = 0,159; p = 0,165). There were no significant differences between treatment groups with respect to demographic data, metabolic control or antihypertensive therapy. Linear regression analysis revealed kidney function as a significant factor influencing insulin dosage in the analogue group, while the corresponding factors in the human insulin group were metabolic control and age.

Conclusion: The results indicate that insulin clearance and/or the metabolic activity of human and analogue insulin differ if renal function is reduced. This may be due to different pharmacokinetic or pharmacodynamic characteristics of these insulins in renal failure, a finding which needs further investigation.