Thyroid hormone levels associate with insulin resistance in obese women with metabolic syndrome in Saudi Arabia: A cross-sectional study

Background The obesity epidemic is a pressing global health concern, as obesity rates continue to climb worldwide. The current study was aimed mainly to evaluate the correlation between thyroid hormones and homeostatic model assessment of insulin resistance in Saudi obese women with metabolic syndrome. Methods 100 obese women aged 25 to 55 years were clinically evaluated, from which 72 women were diagnosed with the metabolic syndrome and 28 without metabolic syndrome. Insulin resistance was quantified using the homeostatic model assessment of insulin resistance method and the resulting values were analyzed for association with demographic, clinical, and metabolic parameters. Results This analysis revealed that body mass index, systolic blood pressure, and biochemical parameters and fasting insulin showed statistically higher levels in the group with metabolic syndrome compared to the group without metabolic syndrome. Similarly, values of waist circumference, fat ratio, cholesterol, free thyroxine, free triiodothyronine and homeostatic model assessment of insulin resistance results were higher in the group with metabolic syndrome as compared to the group without metabolic syndrome. Correlation analysis revealed positive association of thyroid-stimulating hormone with waist circumference (P=0.01), total cholesterol (P=0.002), fasting insulin (P=0.03) and homeostatic model assessment of insulin resistance results (P<0.01), and negatively associated with diastolic blood pressure (P=0.013) and age (P=0.05). Free thyroxine was positively associated with triglyceride level (P=0.003) and negatively associated with homeostatic model assessment of insulin resistance values (P=0.035) and fasting insulin. Free triiodothyronine was positively associated with body mass index (P=0.032) and waist circumference (P= 0.006) and negatively with age (P=0.004) and total cholesterol (P=0.001). Homeostatic model assessment of insulin resistance test revealed elevated level with positive association of body mass index, waist circumference, biochemical parameters and thyroid-stimulating hormone in insulin resistant obese women. Higher level of free triiodothyronine was found to be associated with low insulin sensitivity.


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The obesity epidemic is a pressing global health concern, as obesity rates continue to 29 climb worldwide. The current study was aimed mainly to evaluate the correlation between 30 thyroid hormones and homeostatic model assessment of insulin resistance in Saudi obese women 31 with metabolic syndrome.  biochemical factors) that are associated with developing cardiovascular disease and type 2 66 diabetes mellitus (Ford et al., 2005). A precursor to type 2 diabetes. IR basically refers to the 67 inability of insulin to perform its function at the optimum concentration required for its 68 biological activity (Harris et al., 1998;Ferrannini, 2004). This causes responsible for this 69 inability can range from defective glucose output in the liver to impaired insulin uptake in the 70 muscle (Farasat et al., 2011).

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Healthy thyroid activity is required to maintain the overall health of an individual.

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Several studies have described the effect of thyroid hormones on body mass index (BMI).

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Hypothyroidism leads to weight gain, while hyperthyroidism causes weight loss (Hoogwerf and 74 Nutall, 1984). Moreover, it has also been established that obesity affects thyroid gland function  Therefore, the aim of this cross-sectional study is to identify associations between TSH, 93 IR, and other clinically-relevant metrics in obese women with and without MetS in Saudi Arabia.

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The objectives of this study include: 1) to evaluate the anthropometric, clinical, and biochemical 95 characteristics of the study subjects; 2) to analyze these characteristics for correlations with 96 insulin sensitivity level; 3) to detect associations between TSH levels and the subjects' clinical 97 and biochemical characteristics, MetS diagnosis, and insulin sensitivity level.

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Study subjects 100 The analysis was carried out on 163 obese and overweight women aged 25 to 55 years.

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All of the patients had BMI ≥ 25 kg/m 2 . The presence of medical conditions was assessed 5 102 through self-report. A pre-structured and pre-tested questionnaire were used to gather 103 demographic information and personal and family medical history. Informed consent was 104 obtained from all participants.

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Exclusion criteria 108 Subjects with a history of smoking, polycystic ovary syndrome, chronic renal failure, 109 thyroid disease, chronic hepatopathy, or cancer as well as subjects taking antihypertensive drugs 110 and statins, contraceptive drugs, hormone replacement therapy, any medications known to 111 interfere with glucose and/or insulin secretion and/or metabolism were excluded from the study 112 ( Fig. 1).

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Demographic data 114 A pre-structured and pre-tested questionnaire was used to gather self-reported 115 demographic information and individual and familial medical history.

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Ethical considerations 117 Informed consent was orally obtained from all participants before they gave voluntary 118 consent for this study and approved by IRB.

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Anthropometric measurements 120 Anthropometric measurements were carried out three times by a single tester.

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Height and weight 122 Height was measured without shoes and using a stadiometer. Body weight was morning 123 determined in lightweight clothing, with a digital scale. 125 BMI was calculated as the weight (kilograms) divided by the square of height (meters).

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Waist circumference (WC) 127 Subject's WC was measured using a flexible measuring tape, midway between the 128 xiphoid and the umbilicus during the mid-inspiratory phase.

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Blood pressure (BP) 130 Two BP measurements were taken with the subject in the seated position at a 2-to 3-131 minute interval, after resting for at least 15 minutes. The average of these two readings was used 132 for all patients.

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The comparison between insulin-sensitive and -resistant women in terms of the clinical 175 and metabolic characteristics is presented in Figure 2. Using a cut-off value of 2.7 for HOMA-IR 176 (> 2.7 resistant, < 2.7 sensitive), BMI, WC, TC, TG, LDL-C, FBS, and TSH were higher in the 177 resistant group than the sensitive one. The positive association between IR and BMI (P < 0.001) 178 and WC (P < 0.05) was statistically significant. Similarly, TSH was significantly associated with 179 IR (P = 0.03). Higher FT 3 level associated with low levels of insulin sensitivity.

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Furthermore, hierarchical cluster analysis grouped the clinical and metabolic data according to 181 HOMA-IR values and revealed statistically significant associations between these groups (Fig.   182 3).    In the present study, increased FT 3 levels positively associated with increases in BMI.

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This is in accordance with a previous finding where associations between free or total thyroid