Premium
INSULIN SECRETION, INSULIN SENSITIVITY AND GLUCOSE‐MEDIATED GLUCOSE DISPOSAL IN THYROTOXICOSIS: A MINIMAL MODEL ANALYSIS
Author(s) -
PESTELL RICHARD,
ALFORD FRANK,
RAMOS ROMULUS,
SAWYER STEVEN,
BEST JAMES,
WARD GLENN
Publication year - 1990
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1990.tb03885.x
Subject(s) - euthyroid , medicine , endocrinology , insulin , basal (medicine) , glucagon , glucose tolerance test , insulin sensitivity , hypoglycemia , insulin resistance , hormone
SUMMARY In order to evaluate simultaneously in thyrotoxic subjects the relative contributions of insulin secretion, insulin‐sensitivity (SI) and glucose‐mediated (SG) glucose disposal to overall glucose tolerance, seven non‐obese patients with thyrotoxicosis were studied by the minimal model analysis of the frequently sampled intravenous glucose tolerance test, before and > 1 month after being rendered euthyroid, and compared with eight healthy control subjects. Basal glucose, C‐peptide and glucagon levels were similar in all groups but, in the toxic and euthyroid states, basal insulin levels were significantly elevated compared to the control group (11.2 ±2‐0 and 7.9± 1‐1 vs 5.1 ±0.6 μU/ml, mean±SE, P<0.02). FFA levels were raised in the thyrotoxic subjects prior to treatment (0.95 ±0.11 vs 0.68 ± 0.08 and 054 ± 008 mmol/1, P <0.0). Glucose tolerance (Kg) was reduced in the thyrotoxic subjects compared to the euthyroid state (1.16 ± 0.12 vs 1.44 ± 0.13 per min, P <0.025) and control group (1.44± 1.0 per min, 0.05 < P <0.1). First phase (ψ 1 ) and second phase (ψ 2 ) insulin release were both significantly elevated in the thyrotoxic and euthyroid states compared to the control group (ψ 1 ), 7.10± 1.88 and 5.29± 1.03 vs 1.72 ± 0.17 μU/mg/minx 10 ‐2 P <0.01; ψ 2 18.64 ± 3.14 and 16.74 ± 4.48 vs 9.23 ± 0.74 μU/mg/minx 10 ‐2 respectively, P <0.02). SG was similar in all groups but SI was significantly reduced in the thyrotoxic subjects compared to the control group (2.24 ± 0.62 vs 5.92 ± 1.50/minμU/ml × 10 4 , P <0.02) and rose post‐treatment in the euthyroid subjects (4.23 ± 1.75/minμU/ml × 10 4 ). In the thyrotoxic subjects before and after treatment, log SI correlated negatively with basal FFA levels ( r =‐0.57, P <0.05) and with ψ 2 ( r = ‐0.58, P <0.05). The fractional clearance rate of insulin was unaltered by the thyrotoxic state. It is concluded that in thyrotoxicosis the impairment of Kg is due to reduced insulin sensitivity in the presences of enchanced insulin secretion, but glucose‐medicated glucose disposal is unaltered by the toxic state.