Studies of insulin resistance in patients with clinical and subclinical hypothyroidism

Abstract

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.

Studies of insulin resistance in patients with clinical and subclinical hyperthyroidism

“…Moreover, monocytes express all GLUT isoforms found in muscle and adipose tissue, and the increases in glucose transport in response to insulin in these cells correspond well with those observed in tissues quantitatively important for glucose disposal (15,19). We have previously used monocytes as a cellular model to study insulin sensitivity (11,15); furthermore, we have suggested the important role of GLUT3 in compensating increased tissue demand for glucose in the HR state (20,21).…”

“…Some of the EU volunteers of the present study were used in a similar study published recently by our group (11). The protocol was approved by the hospital ethics committee, and subjects gave informed consent.…”

Comparison of metformin and pioglitazone regarding their influence on thyroid panel, carbohydrate and lipid metabolism in patients with hypothyroidism and established insulin resistance

“…Львівський національний медичний університет імені Данила Галицького, Львів ÂÑÒÓÏ Äîñë³äaeåííÿ îñòàíí³õ ðîê³â âñòàíîâèëè íàÿâí³ñòü ³íñóë³íîðåçèñòåíòíîñò³ ó õâîðèõ íà ã³-ïîòèðåîç [10]. Ç'ÿâèëèñÿ íàóêîâ³ ïðàö³, ùî çà-ïî÷àòêóâàëè âèâ÷åííÿ âïëèâó ³íñóë³íîâèõ ñåí-ñèòàéçåð³â íà òèðåî¿äíèé ñòàòóñ, ïîêàçíèêè âóãëåâîäíîãî òà ë³ï³äíîãî îáì³íó ó õâîðèõ ç ³í-ñóë³íîðåçèñòåíòí³ñòþ òà ñóáêë³í³÷íèì àáî êë³-í³÷íèì ã³ïîòèðåîçîì ³ç öóêðîâèì ä³àáåòîì (ÖÄ) àáî áåç íüîãî [6,8,10].…”

“…Ç'ÿâèëèñÿ íàóêîâ³ ïðàö³, ùî çà-ïî÷àòêóâàëè âèâ÷åííÿ âïëèâó ³íñóë³íîâèõ ñåí-ñèòàéçåð³â íà òèðåî¿äíèé ñòàòóñ, ïîêàçíèêè âóãëåâîäíîãî òà ë³ï³äíîãî îáì³íó ó õâîðèõ ç ³í-ñóë³íîðåçèñòåíòí³ñòþ òà ñóáêë³í³÷íèì àáî êë³-í³÷íèì ã³ïîòèðåîçîì ³ç öóêðîâèì ä³àáåòîì (ÖÄ) àáî áåç íüîãî [6,8,10].…”

Insulin resistance and thyroid hypofunction in obese women – A cross sectional study

“…The association between thyroid function and body weight in euthyroid individuals has been given an important medical concern. The overt hypothyroidism (OH) and sub-clinical hypothyroidism (SCH) are established risk factors for insulin resistance [2,3] and multiple studies have proved the association between insulin resistance, hypothyroidism and metabolic syndrome for overt hypothyroidism [4][5][6][7]. The prevalence of thyroid disease in patients with diabetes is significantly higher than that in the general population [8].…”