Abstract

Aims/hypothesis. Glycation of insulin, resulting in impaired bioactivity, has been shown within pancreatic beta cells. We have used a novel and specific radioimmunoassay to detect glycated insulin in plasma of Type 2 diabetic subjects. Methods. Blood samples were collected from 102 Type 2 diabetic patients in three main categories: those with good glycaemic control with a HbA(1c) less than 7%, moderate glycaemic control (HbA(1c) 7-9%) and poor glycaemic control (HBA(1c) greater than 9%). We used 75 age- and sex-matched non-diabetic subjects as controls. Samples were analysed for HbA(1c), glucose and plasma concentrations of glycated insulin and insulin. Results. Glycated insulin was readily detected in control and Type 2 diabetic subjects. The mean circulating concentration of glycated insulin in control subjects was 12.6 +/- 0.9 pmol/l (n=75). Glycated insulin in the good, moderate and poorly controlled diabetic groups was increased 2.4-fold (p<0.001, n=44), 2.2-fold (p<0.001, n=41) and 1.1-fold (n=17) corresponding to 29.8 +/- 5.4, 27.3 +/- 5.7 and 13.5 +/- 2.9 pmol/l, respectively. Conclusion/interpretation. Glycated insulin circulates at noticeably increased concentrations in Type 2 diabetic subjects.