Acute Effect of Low-Calorie and Low-Carbohydrate Diet on Serum Triiodothyronine-Response to Glucose Ingestion and Its Relation to Glucose Tolerance

Summary

This study was conducted to elucidate the mechanism of glucose intolerance due to carbohydrate restriction. 15 non-diabetic patients, aged 51±3 yr, were placed under dietary condition-I (2,012 kcal/day; carbohydrate 299 g) for more than 3 days after admission and then condition-I was substituted by condition-II (1,156 kcal/day; carbohydrate 139 g) for 2 weeks. At the end of condition-I and -II, 75 g OGTT was performed. After the comparison between condition-I and -II, patients were subdivided into two groups, namely, glucose tolerance-improved (n = 8) and -impaired (n = 7) groups. In the former, Σglucose (mg/dl) during OGTT decreased from 898.1±28.0 to 738.5±36.0 (p<0.05) and ΣIRI (μU/ml) decreased from 418.8±60.1 to 300.7±33.5 (p<0.05) but ΣdT₃ (ng/dl) increased from 11.3±14.7 to 70.3±15.1 (p<0.05). In the latter, Σglucose (mg/dl) increased from 774.6±46.6 to 867.1±50.1 (p<0.05) and ΣIRI (μU/ml) increased from 323.4±47.8 to 400.8±47.8 (p<0.05) but ΣdT₃ (ng/dl) decreased from 45.3±7.1 to 20.0±14.7 although it did not reach a level of statistical significance. These results suggest that blunted serum T₃-response to glucose ingestion is linked to the mechanism of glucose intolerance due to carbohydrate restriction.

Key words

Serum T₃-Response to Glucose Ingestion - Glucose Tolerance - Low-Calorie and Low-Carbohydrate Diet