Basale und reaktive Proinsulin- und Insulinsekretion bei Frauen mit Übergewicht

Abstract

Serum proinsulin and insulin levels were measured on 55 normal or overweight women before and after oral glucose administration. The proinsulin proportion of basal total insulin was 70% in women of normal weight. With increasing overweight the relation shifted in favour of insulin. After stimulation with glucose, proinsulin levels were significantly raised, analogous to total insulin, but les marked than the latter. The increased total insulin excretion in obesity was, therefore, largely due to insulin and less to proinsulin. The greater the overweight the later maximal insulin levels were reached after oral glucose administration: proinsulin peaks occurred later than insulin peaks. Measurement of areas from single values and corresponding times for proinsulin and insulin, after stimulation, indicated their significant correlation with the degree of overweight. In women of more than 70% overweight (Broca index), reactive proinsulin and insulin excretion decreased again despite an increase in body weight. They had a definitely reduced carbohydrate tolerance. After reduction in body weight previously increased proinsulin levels fell again. The significance of higher proinsulin levels in fasting subjects, which increased after stimulation and with overweight but were in percentage terms less than those of reactive insulin, remains unexplained.

Specific and direct radioimmunoassay for human proinsulin in serum

“…The enzymatic degradation method, which is quick and requires only small volumes of serum, seemed an attractive alternative to gel filtration. However, it recorded consistently higher fasting values [5,7] (e. g., 70% proinsulin in normal women [22]) than those recorded by gel filtration. Lately, it has been demonstrated that the degradation of insulin is only partial and dependent on its concentration, and that proinsulin, too, is degraded to some degree [7].…”