The Fasting Serum Insulin and Glucose Levels and the Estimated Insulin Resistance in Clinical and Subclinical Hyperthyroid Patients from Saudi Arabia

Introduction: Hyperthyroidism is associated with insulin resistance, whereas its effect on pancreatic insulin secretion is controversial. The present study was aimed to investigate the influence of hyperthyroidism on the insulin availability and sensitivity and their correlations with the thyroid hormones in patients from Hail region in Saudi Arabia.
Material and methods: The study was conducted on patients with thyroid disorders who were visiting the Diabetic and Endocrinology Unit of King Khalid Hospital, Hail, Saudi Arabia between April 2015 and July 2015. A total of 43 newly diagnosed hyperthyroid patients (age range: 18-77 years) were classified into: • Subclinical hyperthyroid (SHR) group: with serum TSH<0.40 mU/L and with normal FT₄ • Overt Hyperthyroid (OHR) group with TSH<0.40 mU/L and FT₄>25.0 pmol/L • Control (C) group of normal subjects
Results: The fasting serum insulin levels in the SHR and OHR groups were severely raised by 6.22-fold and 7.67-fold, and the serum glucose by 28.76% and 54.79%, respectively compared to control, whereas, the kidney function was not altered in any of the groups. On the other hand, there were significant correlations between TSH and insulin levels (r=-0.79, P=0.0001), FT₄ and insulin (r=0.34, P=0.03), TSH and insulin resistance (r =-0.5, P=0.001) and between TSH and insulin sensitivity index (r=0.90, P=0.000).
Conclusion: Both clinical and subclinical hyperthyroid patients had significantly elevated fasting serum insulin and glucose levels and increased insulin resistance. Significant correlations exist between TSH and T₄ with insulin levels, and between TSH with insulin resistance. The hyperthyroidism had no detrimental effects on the renal function.

Author(s): Abdel-Gayoum AA*

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