Glucose metabolism in noninsulin-dependent diabetic patients with experimental hyperthyroidism.
Hyperthyroidism is known to further impair carbohydrate metabolism in diabetic patients. In the present study we examined in noninsulin-dependent (type 2) diabetic patients the effect of T3-induced hyperthyroidism on glucose utilization and endogenous glucose production by means of the hyperinsulinemic and hyperglycemic clamp technique in combination with [3H]3-glucose kinetic analysis. Administration of T3 for 1 week increased the mean serum T3 concentration from 1.0 +/- 0.1 (SEM) to 4.1 +/- 0.2 ng/ml, and the mean fasting plasma glucose from 8.7 +/- 0.7 to 9.9 +/- 0.9 mmol/liter. Basal hepatic glucose production (HGP) rose from 3.23 +/- 0.23 to 3.98 +/- 0.25 mg/kg X min, whereas basal MCR of glucose (MCRG) increased only slightly from 2.12 +/- 0.24 to 2.30 +/- 0.14 ml/kg X min. When the plasma insulin concentration was acutely raised and maintained at 82 +/- 8 microU/ml (hyperinsulinemic clamp study), HGP decreased to 0.71 +/- 0.29 mg/kg X min and MCRG increased to 3.16 +/- 0.47 ml/kg X min. After T3 administration suppression of HGP by insulin was reduced (1.55 +/- 0.37 mg/kg X min), but at the same time MCRG was only slightly affected (3.64 +/- 0.54 ml/kg X min). In the hyperglycemic clamp study the plasma glucose concentration was maintained 7 mmol/liter above the individual fasting level. MCRG was again slightly higher after T3 administration (1.98 +/- 0.18 vs. 1.66 +/- 0.15 ml/kg X min), but insufficient to completely compensate for the higher residual HGP at the hyperthyroid as compared to the euthyroid state (2.42 +/- 0.24 vs. 1.45 +/- 0.36 mg/kg X min). Thus, deterioration of metabolic control in noninsulin-dependent diabetic patients by hyperthyroidism is due primarily to enhancement of basal HGP and its reduced suppressibility by insulin and glucose.
D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications* / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D014284:Triiodothyronine / Q000008:administration & dosage / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D014284:Triiodothyronine; D005947:Glucose