HUMAN INSULIN - ADVANTAGES AND DRAWBACKS

Insulin (I) preparations used formerly contained a large number of protein contaminants which are thought to be immunogenic and, hence, caused lipodystrophy, I-allergy and sometimes antibody-mediated I-resistance in many patients. Monocomponent (MC)-I and human I (HI) are virtually free of these peptides and are, therefore, very rarely accompanied by the above-mentioned immunologic side effects. In this respect, however, HI offers only little advantage over MC-I although HI is the least immunogenic I. On the other hand, the formation of antibody to I in the diabetic mother is an important determinant of fetal outcome. And since children from diabetic mothers treated with HI are less frequently macrosomic, the use of HI is strongly recommended in women with diabetes before and during their childbearing years. Neutral HI action is somewhat shorter, although clinically not to a relevant extent and, furthermore, metabolic control is not improved by using HI compared with MC-I. These findings have been regarded as disadvantages of HI, together with the fact that about 20% of HI-treated patients experience a change of hypoglycemia symptoms during the course of their illness. While autonomic symptoms become weaker or disappear, patients have to react to neuroglycopenic symptoms which normally remain constant. However, the incidence of hypoglycemic events does not change during treatment with HI. Several reasons for this change of symptoms are discussed, such as long duration of diabetes, intensified therapy with near-normoglycemia, development of autonomic neuropathy, alcoholic beverages, and often insufficient instruction of patients. Therefore, treatment with HI is efficient and safe but is especially advantageous before and during pregnancy, in cases in which I-treatment is intended to be intermittent, and in patients with immunologic side effects of I. Patients must be very carefully briefed before their treatment is changed to HI and the initial HI-dose should be reduced by about 10% to avoid hypoglycemia. The cause of the change in hypoglycemia symptoms can only be elucidated in studies involving patients who are affected. Rather than coming to hasty conclusions it is necessary to consider the long-term course of diabetes for which it is advantageous if patients accustom themselves to lower glucose levels (possibly with other hypoglycemic symptoms), provided they can manage hypoglycemic events themselves thanks to adequate instruction.