Hyperinsulinemia and insulin resistance is associated with low T₃/T₄ ratio in pre diabetic euthyroid Pakistani subjects.
OBJECTIVE
To investigate the relationship of thyroid hormones in glucose homeostasis in impaired glucose-tolerant subjects with normal thyroid functions.


METHODS
Cross-sectional analysis was carried out in (n=260) impaired glucose-tolerant (IGT) and normal glucose-tolerant (NGT) subjects. Thyrotropin (TSH), total triiodothyronine (TT₃), total thyroxin (TT₄) free T₃ (fT₃), free T₄ (fT₄), and insulin were assessed by enzyme-linked immunoassays (ELISA). Fasting plasma glucose (FPG) and HbA1c were measured by glucose oxidase and low-pressure cation exchange chromatography. Homeostasis model of assessment (HOMA-IR) was employed to assess the level of insulin resistance; fT₃/fT₄ ratio was calculated. Anthropometric measurement and habits were recorded.


RESULTS
Marked hyperinsulinemia and insulin resistance were observed in IGT subjects. Serum TT₃ and fT₃ levels were significantly low in the IGT as compared to normal glucose-tolerant (NGT) controls. TT₄ and TSH were higher in IGT subjects as compared to control subjects. There was a significant positive correlation of TSH with BMI only in the control group (r=0.351; P<0.05). Correlation of insulin with TT₃, fT₃,and TSH was significant (P<0.05) in IGT subjects. A significant low fT₃/fT₄ ratio was observed in IGT subjects as compared to NGT subjects (P<0.01). In multiple regression analysis, TSH, TT₄ and fT₃ contributed significantly to the variance of fasting insulin and insulin resistance in IGT subjects.


CONCLUSIONS
Hyperinsulinemia and insulin resistance are associated with low T₃/T₄ ratio in pre-diabetic euthyroid Pakistani subjects.
Department of Zoology, Lahore College for Women University, Lahore, Pakistan. tasnimfarasat@hotmail.com
Tasnim
T
Farasat
Abdul Majeed
AM
Cheema
Muhammad Naeem
MN
Khan
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology*; D006946:Hyperinsulinism / Q000209:etiology*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000150:complications; D010154:Pakistan; D011236:Prediabetic State / Q000097:blood / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology*; D012044:Regression Analysis; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D006442:Glycated Hemoglobin; D013972:Thyrotropin; D013974:Thyroxine; D014284:Triiodothyronine; C517652:hemoglobin A1c protein, human