Subclinical Hypothyroidism Is Associated with Early Insulin Resistance in Kuwaiti Women

Insulin resistance is defined as a glucose homeostasis disorder involving a decreased sensitivity of muscles, adipose tissue, liver and other body tissues to insulin, despite its normal or increased concentration in blood. Insulin resistance may be asymptomatic or occur presenting a variety of disorders, such as: glucose tolerance impairment, type 2 diabetes, as well as hypercholesterolaemia, hypertriglyceridaemia, obesity, and arterial hypertension. Insulin acts via specific receptors present on the surface of most cells of the body. The greatest number of these receptors is found on adipocytes, hepatocytes and striated muscle cells. There are three mechanisms of insulin resistance: pre-receptor, receptor and post-receptor. Multiple methods of assessing insulin resistance are based on the concurrent measurements of glucose and insulin levels in blood serum. The glucose and insulin measurements are conducted in baseline conditions or after intravenous administration of a specific quantity of glucose or insulin. The methods of assessing insulin resistance are divided into direct and indirect. The current 'gold standard' in the assessment of insulin sensitivity is the determination of tissue glucose utilisation using the metabolic clamp technique. The presence of disorders of carbohydrate metabolism has been demonstrated in thyroid disease involving either overt hyperthyroidism or overt hypothyroidism. The severity of the disease is proportional to the severity of these disorders. The possible influence of subclinical forms of both hyperthyroidism and hypothyroidism on carbohydrate disorders is still under discussion. Thyroid hormones have a significant effect on glucose metabolism and the development of insulin resistance. In hyperthyroidism, impaired glucose tolerance may be the result of mainly hepatic insulin resistance, whereas in hypothyroidism the available data suggests that the insulin resistance of peripheral tissues prevails. StreszczenieInsulinooporność definiuje się jako zaburzenie homeostazy glukozy polegające na zmniejszonej wrażliwości mięśni, tkanki tłuszczowej, wątroby oraz innych tkanek na insulinę pomimo jej prawidłowego lub podwyższonego stężenia we krwi. Insulinooporność może przebiegać bezobjawowo lub towarzyszyć różnorodnym chorobom i zaburzeniom, takim jak upośledzona tolerancja glukozy, cukrzyca typu 2, hipercholesterolemia, hipertriglicerydemia, otyłość i nadciśnienie tętnicze. Insulina działa za pośrednictwem swoistych receptorów obecnych na powierzchni większości komórek organizmu. Najwięcej tych receptorów stwierdza się na komórkach tłuszczowych, hepatocytach i komórkach mięśni poprzecznie prążkowanych. Wyróżnia się trzy rodzaje insulinooporności: przedreceptorową, receptorową i poreceptorową. Metody rozpoznawania insulinooporności oparte są na jednoczesnym oznaczaniu stężenia glukozy i insuliny w surowicy krwi. Pomiary stężenia glukozy i insuliny wykonywane są albo w warunkach podstawowych, albo po dożylnym podaniu określonej ilości glukozy lub insuliny. Metody oceny insulin...

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“…Yet, the results of other studies indicate a normal insulin sensitivity in that group of patients [34,35].…”

Section: Hypothyroidismmentioning

confidence: 74%

Insulinooporność a choroby tarczycy

Gierach¹,

Gierach²,

Junik³

2014

Endokrynologia Polska

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“…They found that the insulin levels were significantly higher in the Subclinical hypothyroidism group comparable to the normal control. 15 Another study by Christy et al selected 30 hypothyroid, non-diabetic patients with normocytic normochromic anaemia and compared these patients with 30 euthyroid non-diabetic patients also with normocytic normochromic anaemia. HbA1c in the hypothyroid patients was 6.32±0.75% versus 5.87±0.46% in the euthyroid group, the difference being statistically significant.…”

Section: Discussionmentioning

confidence: 99%

Association of subclinical hypothyroidism and HbA1c levels in non-diabetic subjects attending rural tertiary care centre in central India

Ram

Kumar

et al. 2017

Int J Res Med Sci

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NTRODUCTIONThyroid disorders are very common in the general population and is second most common condition affecting the endocrine system after diabetes mellitus. Decreased production of thyroid hormone is the key feature of hypothyroidism.2 Subclinical hypothyroidism is defined as an elevated serum TSH level and normal concentrations of free T3 (FT3), free T4 (FT4), T3 and T4.1 It is often complicated by conditions such as dilutional hyponatremia, anaemia and hyperlipidemia. Subclinical hypothyroidism is more common in the elderly and is more prevalent in women than in men. 4,5 The American Diabetes Association (ADA) have approved the use of HbA1c for the screening and the diagnosis of diabetes. 6 The HbA1c concentration not only depends on prevailing glycaemia but also the life span of the erythrocytes and so, the conditions which affect the erythrocyte turnover or survival may lead to falsely elevate or lower the HbA1C levels.7-11 A positive association between thyroid and diabetes mellitus is well recognized but to study the effect of thyroid disorders on glucose metabolism in non-diabetic patients is an area for extensive research. Recent studies have shown its spurious elevation in hypothyroidism in the absence of diabetes.1,2 Present study was planned to assess ABSTRACTBackground: Subclinical hypothyroidism is defined as an elevated serum TSH level and normal concentrations of free T3 (FT3), free T4 (FT4), T3 and T4. A positive association between thyroid and diabetes mellitus is well recognized but to study the effect of thyroid disorders on glucose metabolism in non-diabetic patients is an area for extensive research. Present study was planned to assess correlation between subclinical hypothyroidism and glycosylated haemoglobin levels in non-diabetic patients. Methods: A case-control study was conducted on total 209 subjects. 109 patients were allotted in case group and 100 in control group. Controls were relatives and friends of patients who were matched for age and sex. Comparison between the case and the control groups were made using Student's t-test (unpaired) and Box and Whisker Plot and regression graph were presented for correlation between serum TSH and HbA1c. Results: It was found that there was a positive correlation between the levels of serum TSH (µU/L) and HbA1c (%) in all the participants of the study by Pearson's correlation coefficient (r=0.35, p < 0.0001). Conclusions: HbA1c levels are increased in subclinical hypothyroid patients. The effects of the elevated levels of Serum TSH on the HbA1c must be considered when interpreting the HbA1c for the diagnosis of diabetes or prediabetes in the subclinical hypothyroid patients.

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“…In this condition, data regarding insulin effects on glucose metabolism are contradictory: insulin sensitivity in the fasting state (assessed with homeostasis model assessment (HOMA) index) has been found to be either normal (5,6) or decreased (7). However, in patients with SHO, fasting hyperinsulinemia has been reported (7,8).…”

Section: Introductionmentioning

confidence: 99%

Studies of insulin resistance in patients with clinical and subclinical hypothyroidism

Maratou

Hadjidakis²,

Κόλλιας³

et al. 2009

European Journal of Endocrinology

367

277

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Objective: Although clinical hypothyroidism (HO) is associated with insulin resistance, there is no information on insulin action in subclinical hypothyroidism (SHO). Design and methods: To investigate this, we assessed the sensitivity of glucose metabolism to insulin both in vivo (by an oral glucose tolerance test) and in vitro (by measuring insulin-stimulated rates of glucose transport in isolated monocytes with flow cytometry) in 21 euthyroid subjects (EU), 12 patients with HO, and 13 patients with SHO. Results: All three groups had comparable plasma glucose levels, with the HO and SHO having higher plasma insulin than the EU (P!0.05). Homeostasis model assessment index was increased in HO (1.97G0.22) and SHO (1.99G0.13) versus EU (1.27G0.16, P!0.05), while Matsuda index was decreased in HO (3.89G0.36) and SHO (4.26G0.48) versus EU (7.76G0.87, P!0.001), suggesting insulin resistance in both fasting and post-glucose state. At 100 mU/ml insulin: i) GLUT4 levels on the monocyte plasma membrane were decreased in both HO (215G19 mean fluorescence intensity, MFI) and SHO (218G24 MFI) versus EU (270G25 MFI, PZ0.03 and 0.04 respectively), and ii) glucose transport rates in monocytes from HO (481G30 MFI) and SHO (462G19 MFI) were decreased versus EU (571G15 MFI, PZ0.04 and 0.004 respectively). Conclusions: In patients with HO and SHO: i) insulin resistance was comparable; ii) insulin-stimulated rates of glucose transport in isolated monocytes were decreased due to impaired translocation of GLUT4 glucose transporters on the plasma membrane; iii) these findings could justify the increased risk for insulin resistance-associated disorders, such as cardiovascular disease, observed in patients with HO or SHO.

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Subclinical Hypothyroidism Is Associated with Early Insulin Resistance in Kuwaiti Women

Cited by 58 publications

References 22 publications

Insulinooporność a choroby tarczycy

Insulinooporność a choroby tarczycy

Association of subclinical hypothyroidism and HbA1c levels in non-diabetic subjects attending rural tertiary care centre in central India

Studies of insulin resistance in patients with clinical and subclinical hypothyroidism

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