Evaluation of insulin resistance in non-obese subjects with impaired glucose tolerance.
Insulin resistance was estimated in nine subjects with impaired glucose tolerance (IGT) and eleven healthy, age and body-weight matched controls. Glucose tolerance and insulin response were evaluated by means of a 2h-glucose infusion test. Insulin resistance was determined by measuring the steady state plasma glucose response (SSPG) to a continuous infusion of glucose (6 mg . kg-1 . min-1 or 12 mg . kg-1 . min-1), insulin, epinephrine and propranolol for 150 minutes as described previously by other authors. The endogenous insulin secretion (C-peptide) was inhibited by epinephrine and propranolol in controls and subjects with IGT irrespective of a low (6 mg . kg-1 . min-1) or high (12 mg . kg-1 . min-1) glucose infusion. Steady-state plasma levels of exogenous insulin were virtually identical in all groups studied. There were no significant differences in the pancreatic glucagon, growth hormone, FFA and glycerol response during the SSPG period between controls and subjects with IGT. In comparison to controls the mean SSPG was significantly higher in subjects with IGT (during low and high glucose infusion) suggesting the existence of insulin resistance in these subjects. A higher glucose dose as described earlier by other investigators does not provide a better discrimination of controls and subjects with IGT concerning their degree of insulin resistance. Finally, there was a direct correlation between the SSPG and glucose tolerance in the total group. In conclusion, our results have confirmed the validity of an infusion technique of glucose, insulin, epinephrine and propranolol for evaluation of insulin sensitivity in vivo. In addition, our findings have added further support for insulin resistance in subjects with IGT which is directly proportional to the degree of glucose intolerance.
D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000378:metabolism; D004837:Epinephrine; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005934:Glucagon / Q000097:blood; D005951:Glucose Tolerance Test; D005990:Glycerol / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D007700:Kinetics; D008297:Male; D011433:Propranolol; D012016:Reference Values
D001786:Blood Glucose; D002096:C-Peptide; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005934:Glucagon; D011433:Propranolol; D005990:Glycerol; D004837:Epinephrine