triiodothyronine--reverse and Diabetes-Mellitus--Type-2

Thyroid hormone (TH) abnormalities are common in patients with diabetes mellitus (DM). These thyroid hormone abnormalities have been associated with inflammatory activity in several conditions but this link remains unclear in DM. We assessed the influence of subclinical inflammation in TH metabolism in euthyroid diabetic patients. Cross-sectional study involving 258 subjects divided in 4 groups: 70 patients with T2DM and 55 patients with T1DM and two control groups of 70 and 63 non-diabetic individuals, respectively. Groups were paired by age, sex, and body mass index (BMI). We evaluated the association between clinical and hormonal variables [thyrotropin, reverse T3 (rT3), total and free thyroxine (T4), and triiodothyronine (T3)] with the inflammation markers C-reactive protein (hs-CRP), serum amyloid A (SAA), and interleukin-6 (IL-6). Serum T3 and free T3 were lower in patients with diabetes (all P < 0.001) compared to the control groups. Interleukin-6 showed positive correlations with rT3 in both groups (P < 0.05). IL-6 was independently associated to FT3/rT3 (B = -0.193; 95% CI -0.31; -0.076; P = 0.002) and FT4/rT3 (B = -0.107; 95% CI -0.207; -0.006; P = 0.039) in the T1DM group. In the T2DM group, SAA (B = 0.18; 95% CI 0.089; 0.271; P < 0.001) and hs-CRP (B = -0.069; 95% CI -0.132; -0.007; P = 0.03) predicted FT3 levels. SAA (B = -0.16; 95% CI -0.26; -0.061; P = 0.002) and IL6 (B = 0.123; 95% CI 0.005; 0.241; P = 0.041) were related to FT4/FT3. In DM, differences in TH levels compared to non-diabetic individuals were related to increased subclinical inflammatory activity and BMI. Altered deiodinase activity was probably involved. These findings were independent of sex, age, BMI, and HbA1c levels.

Topics: Adult; Asymptomatic Diseases; C-Reactive Protein; Case-Control Studies; Cross-Sectional Studies; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Female; Humans; Inflammation; Interleukin-6; Male; Middle Aged; Serum Amyloid A Protein; Thyroid Diseases; Thyroid Function Tests; Thyroid Hormones; Triiodothyronine, Reverse; Young Adult

The mitochondrial uncoupling proteins (UCP-2 and UCP-3), which have been suggested to be involved in the development of obesity by controlling the energy expenditure (EE), were studied in 22 healthy first-degree relatives (FDRs) of patients with type 2 diabetes and 13 body mass index (BMI)- and age-matched healthy control subjects. Abdominal subcutaneous adipose tissue biopsies were obtained before and after 150-min hyperinsulinaemic clamp (average serum insulin 250 pM). Basal adipose tissue UCP-2 mRNA levels in the FDR group were significantly lower than that in the control group. After the hyperinsulinaemic clamp, adipose tissue UCP-2 mRNA levels were increased by 32% in the control group (p < 0.05) and 32% in the FDR group (p < 0.05). The basal adipose tissue UCP-3 mRNA level was similar in the two groups and increased in both the groups during hyperinsulinaemia (p < 0.001). Dual energy X-ray absorptiometry showed that despite similar BMI the FDR group had significantly higher fat mass (FM) per cent compared to that of the control group (p < 0.01). The UCP-2 mRNA expression was inversely correlated with the amount of adipose tissue (r = -0.53, p < 0.001), and multiple regression analysis revealed that only the amount of FM was independently correlated with basal UCP-2 mRNA levels, whereas age, gender nor family history of type 2 diabetes contributed independently to the variation in UCP-2 mRNA levels. No differences in EE were observed between the two groups, and no association between EE and UCP mRNA expression was found. In conclusion, we have demonstrated that adipose tissue UCP-2 and UCP-3 mRNA levels are significantly increased during a 150-min hyperinsulinaemic clamp. The UCP-2 mRNA levels were expressed at a significantly lower level FDR to type 2 diabetes compared to control subjects. However, in multiple regression analysis controlling for amount of adipose tissue, the difference between the two groups disappeared. Thus, only the amount of adipose tissue contributed independently to the variation in UCP-2 mRNA expression.

Topics: Adipose Tissue; Adult; Body Composition; Calorimetry, Indirect; Carrier Proteins; Case-Control Studies; Diabetes Mellitus, Type 2; Female; Gene Expression; Humans; Insulin; Ion Channels; Male; Membrane Transport Proteins; Mitochondrial Proteins; Regression Analysis; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse; Uncoupling Protein 2; Uncoupling Protein 3

Using radioligand binding assay of receptors, we studied the changes of T3 receptors in circulating lymphocytes in 20 normal persons and 43 diabetic patients with or without low T3. The mean value of serum T3 and FT3 was significantly decreased in all diabetic patients compared with that of normal controls. The concentration of serum T3 was negatively correlated with fasting blood glucose level. The serum rT3 was clearly increased in patients with low T3. The serum T4, FT4, FT4 I and TSH were normal in all patients The maximal binding capacity (MBC) of circulating lymphocyte T3 receptors which was negatively correlated with the serum T3 concentrations was obviously elevated in patients with diabetes mellitus. It was still higher in patients with low T3 than in patients with normal T3, whereas the affinity of receptor was not changed. In conclusion, the increment of T3 receptor binding capacity reflects the compensatory mechanisms, which are probably evoked by the T3 deficiency in order to maintain cellular homeostasis.

Topics: Adult; Aged; Diabetes Mellitus, Type 2; Female; Humans; Lymphocytes; Male; Middle Aged; Receptors, Thyroid Hormone; Triiodothyronine; Triiodothyronine, Reverse

Topics: Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Female; Humans; Male; Syndrome; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Altered thyroid hormone metabolism with decreased serum T3 and increased rT3 concentrations in patients with uncontrolled diabetes mellitus has been well documented. However, data regarding TSH secretion are sparse, especially the influence of glycemic control. Therefore, we examined serum T4, free T4, T3, rT3, T3 resin uptake, and TSH as well as the TSH response to TRH administration [expressed as TSH increment (delta TSH) and area under the curve (theta TSH)] in 29 newly discovered type II diabetic patients (DM) before treatment and in 12 normal subjects. The study was repeated in the DM patients after attainment of euglycemia and normalization of glycosylated hemoglobin (HbA1C) following therapy with diet and tolazamide for 8-12 weeks. Serum T4, free T4, and T3 resin uptake were not significantly different in DM compared to those in normal subjects. Serum T3 was low and rT3 was high in DM before treatment, and both normalized on achieving the euglycemic state. Basal TSH in uncontrolled DM was not significantly different from that in normal subjects and remained unchanged during treatment. However, delta TSH and theta TSH were significantly reduced (P less than 0.01) in uncontrolled DM. Both fasting plasma glucose (FBS) and HbA1C levels correlated inversely with delta TSH as well as theta TSH (FBS vs. delta TSH, r = -0.42; FBS vs. theta TSH, r = -0.38; HbA1C vs. delta TSH, r = -0.40; HbA1C vs. theta TSH, r = -0.42; P less than 0.05 for all correlations). Finally, TSH responses returned to normal on attainment of euglycemia and normal HbA1C concentrations. These studies indicate that regulation of TSH secretion is altered in DM during the decompensated state and normalizes when euglycemia is achieved.

Topics: Blood Glucose; Diabetes Mellitus, Type 2; Humans; Insulin; Male; Middle Aged; Pituitary Gland, Anterior; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Several studies have demonstrated that the uncontrolled diabetic state in both type I as well as type II diabetes mellitus is characterized by altered thyroid hormone metabolism, which results in the lowering of serum triiodothyronine (T3) levels and a reciprocal elevation of T3 (rT3) levels. Because the majority of type II diabetics are over 50 years of age and because numerous previous reports have implicated aging as a cause of low T3 and high rT3 levels, we studied 220 type II diabetics from 40-85 years of age to assess the influence of aging and metabolic control on thyroid hormone levels. Serum thyroxine (T4) free T4, T3 resin uptake, and thyroid-stimulating hormone (TSH) measurements in diabetic patients were not significantly altered compared with 37 young normal control subjects, irrespective of age or the grade of metabolic control. Serum T3 levels declined and rT3 levels rose in the diabetic patients with worsening of the metabolic control. However, with comparable metabolic control, the levels were not significantly different from the younger patients. Therefore, low T3 and high rT3 levels observed in patients of any age who have type II diabetes mellitus may be exclusively caused by deranged metabolic control of their disease.

Topics: Adult; Aged; Aging; Blood Glucose; Diabetes Mellitus, Type 2; Humans; Male; Middle Aged; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse