Thyroid hormones are positively associated with insulin resistance early in the development of type 2 diabetes

Abstract

Thyroid hormones have generally been found normal in diabetic patients. The question of whether variation within the euthyroid range influences insulin sensitivity in type 2 diabetes remains to be established. To investigate this, a meal was given to four groups: 17 healthy volunteers (controls), 22 first-degree relatives of type 2 diabetic subjects (relatives), 15 subjects with impaired glucose tolerance (IGT), and 24 subjects with overt type 2 diabetes (DM). Blood was drawn for 360 min for measurements of glucose and insulin. Plasma-free-T4(FT4) and plasma-free-T3(FT3) levels were measured. Fasting and postprandial insulin resistance was assessed by HOMA-IR and ISI indices, respectively. FT4 levels were found to be lower in controls (13.73 ± 0.48 pmol/l) than relatives, IGT, and DM (15.33 ± 0.52, 16.13 ± 0.65, and 17.7 ± 0.85 pmol/l, respectively, P = 0.007). FT3 levels were lower in controls (3.68 ± 0.09 pmol/l) than in relatives, IGT, and DM (4.35 ± 0.1, 4.8 ± 0.067, and 4.87 ± 0.11 pmol/l, respectively, P = 0.001). HOMA-IR was positively associated with FT4 and FT3 levels (β-co-efficient = 1.876 ± 0.476, P = 0.001; and 0.406 ± 0.090, P = 0.001, respectively). ISI was negatively associated with FT4 and FT3 levels (β-co-efficient = -0.051 ± 0.009, P = 0.001 and -0.009 ± 0.002, P = 0.001, respectively). In conclusion, increases of thyroid hormone levels within the normal range associate positively with insulin resistance. These data suggest that thyroid hormones may be part of the pathogenetic mechanism to explain metabolic derangement early in the development of type 2 diabetes.

Bone Marrow-Derived Mesenchymal Stem Cells Ameliorate the Pancreatic Changes of Chemically Induced Hypothyroidism by Carbimazole in Male Rats

“…HT-associated complications have become a concerning issue, as metabolic disturbances such as dyslipidemia and insulin resistance have been demonstrated in even subclinical HT patients (euthyroid level) [Lambadiari et al, 2011].…”

Body composition and metabolic parameters are associated with variation in thyroid hormone levels among euthyroid young men

“…Apart from the mutual association with body composition, there may also be a direct link between thyroid function and glucose metabolism. With regard to thyroid dysfunction, both hyper-and hypothyroidism have been reported to be associated with IR (17). This apparent paradox may result from the differential effects of thyroid hormones at the level of the liver (insulin antagonistic) and peripheral tissues (e.g.…”

“…Furthermore, both hyper-and hypothyroidism have been reported to be associated with insulin resistance (IR) (17). Moreover, administration of T 3 to normal volunteers results in IR (18).…”

Complications of Hyperthyroidism

“…The pathogenetic mechanism can be explained by insulin resistance and metabolic derangement [414]. A study showed that patients on treatment for hyperthyroid Graves' disease were almost twice as likely to develop type 2 diabetes than the general population, although they were less likely to be overweight and were less likely to have family history.…”