The KID Study V: the natural history of type 2 diabetes in younger patients still practising a profession. Heterogeneity of basal and reactive C-peptide levels in relation to BMI, duration of disease, age and HbA(1)

In a detailed evaluation of the data accumulated for 493 type 2 diabetics w ho participated in the IUD Study, pre- and postprandial C-peptide was corre lated with blood glucose level, HbA(1), body mass index (BMI), duration of disease and age. As described earlier the KID-Study examined a younger coho rt of type 2 diabetics predominately practising a profession. Our investigations demonstrate a significant increase of pre- as well as po stprandial C-peptide levels with increasing obesity. However, delta C-pepti de, as an indicator at the reaction capacity of pancreatic secretion, decre ases significantly and continuously. Pre- as well as postprandial C-peptide levels decrease significantly with up to 15-20 years duration of disease T he preprandial pancreatic secretion is usually even at a high normal level at such a late stage whereas the secretory reserve of normal or mildly over weight as well as of obese type 2 diabetics is more impaired. In contrast t o patients with a BMI < 30, obese patients with a BMT > 30 will also develo p impairment of basal insulin secretion over decades. The patient's age did not influence the pre- or postprandial insulin secretion. The quality of m etabolic control as measured by the HbA(1) has nearly exclusive impact on t he secretory reserve capacity. Correlation with increasing HbA(1) concentra tions, the postprandial but not the preprandial C-peptide levels decreased significantly and continuously. Predictive factors for a deterioration in pancreatic function are in order of importance: the extent of obesity, the quality of metabolic control and only last the duration of diabetes. Fortunately, consistent diabetic care c an have an impact on the first two.