Novel insulin analogues and its mitogenic potential.
Insulin analogues were developed to modify the structure of the human insulin molecule in order to more accurately approximate the endogenous secretion of insulin. With the help of recombinant technology and site-directed mutagenesis, the insulin molecule can be modified to either delay or shorten absorption time, providing better insulin treatment options and facilitating the achievement of glycaemic goals. Changing the structure of the insulin molecule, however, may significantly alter both its metabolic and mitogenic activity. Multiple factors such as residence time on the receptor, dissociation rate, rate of receptor internalization and the degree of phosphorylation of signalling proteins can affect the mitogenic potencies of insulin analogues. Changes in the structure of the insulin have raised concern about the safety of the insulin analogues. For example, questions have emerged about the relationship between the use of insulin lispro and insulin glargine and the progression of diabetic retinopathy. Two studies have shown progression of retinopathy with the use of insulin lispro. However, others have not confirmed these results, and causality could not be proven as progression of retinopathy can occur with rapid improvement in glycaemic control, and methods of assessments among studies were not consistent. Therefore, we examine the metabolic and mitogenic characteristics of the three insulin analogues, insulin lispro, insulin aspart and insulin glargine, that are currently on the market, as well as the two insulin analogues, insulin glulisine and insulin detemir, that are soon going to be available for clinical use.