Hepatic extraction of insulin in non-insulin dependent diabetes. Comparative study of obese and non-obese patients

Changes in the secretion and metabolism of insulin were measured by estimating serum C-peptide and insulin and their ratio during oral GTT in 30 non obese and 12 obese NIDDM patients. The mean IRI and CP responses were low in both groups of patients, compared to weight-matched controls. The reduction in CP was more marked than the reduction in IRI. The molar ratio of insulin and CP was found to be elevated in the patients, probably indicating reduced hepatic and peripheral extraction of insulin. It was noted that the elevated IRI/CP ratio was a 1) a common feature in NIDDM, irrespective of the body weight, 2) it is present even under basal conditions when the insulin levels are the lowest, 3) it appears to be independent of the concentration of insulin reaching the liver, and 4) obese patients appear to have an exaggerated defect compared to their non obese counterparts