Serum Thyroid Hormones Pictures in Non Thyroidal Illness Syndrome and Circulating Leptin Concentration in Patients with Uncontrolled Type 2 Diabetes Mellitus in a Group of Bangladeshi Population

Abstract

Background: Thyroid diseases and diabetes mellitus are common endocrine disorders and Euthyroid Sick Syndrome is very common in uncontrolled type2 Diabetes Mellitus. As of thyroid hormones; the catabolic hormone Leptin is thought be closely linked with Diabetes Mellitus and Euthyroid Sick Syndrome. Objective: To evaluate the thyroid hormone pictures in absence of clinical thyroid diseases among type2 diabetic subjects in a Bangladeshi population. To see the baseline serum leptin concentration in a group of Bangladeshi adult population and to document how the leptin is related to glycemic status and Sick Euthyroid syndrome in the setting of uncontrolled type 2 Diabetes Mellitus. Method: This case and control study was carried out in the Endocrinology Department in collaboration with the Bio-Medical Research Group (BMRG), Research Division, Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrinology and Metabolism (BIRDEM)), Dhaka, Bangladesh during the period of January 2000 to December 2002. A total of 100 type 2 diabetic subjects, 30-50 years of age, irrespective of glycemic status, duration of diabetes, Body Mass Index (BMI) and sex were recruited from the outpatient department (OPD) of BIRDEM hospital. Control subjects (n=30) were selected from friends and family of the patients within 5 years of age band without diabetes or impaired glucose regulation {Impaired Fasting Glycemia (IFG), Impaired Glucose Tolerance (IGT)} determined according to American Diabetic Association (ADA) criteria [37] and having no clinical thyroid diseases or other evident systemic diseases documented on clinical evaluation. Results: It was observed that mean± SD of the thyroid hormone pictures in diabetic and control subjects were; TT3 (ngm/dl) {in controls (88.91±15.88) and in diabetic subjects (84.27±22.29)} was not statistically significant to each other (p=0.209). Mean±SD of TT4 (µgm/ dl) in control subjects was 8.32±1.64 and in the diabetic subjects was 9.26±1.44, which is almost similar in both the groups (p= 0.589). FT4: (pgm/ml) in control subjects was 2.60±0.54 and in diabetics was 2.53±1.72 (p= 0.830). FT4. (µgm/ dl) in control subjects was 1.43±0.22 and in diabetics subjects 1.36±0.25. (p 0.179). TSH (µlu/ml) in control subjects was 1.34±1.00 and in diabetic subjects 1.54±1.21 (p: 0.411). FT3; FT4 and TSH showed no significant difference between control and diabetic subjects. Thyroid hormones (TT3, TT4, FT3, FT4) and TSH were reanalyzed according to HbA1c and BMI category and showed no significant differences. But when the FPG and HbA1c goes beyond 12 mmol/l and 10% respectively there was more worsening thyroid hormone pictures in comparison to groups whose FPG and HbA1c were below 12mmol/l and 10%. It was also noticed that there was a tendency to develop lower thyroid hormone pictures and more deteriorating glycemic status in patient with low and normal BMI groups in comparison to higher BMI groups of patients. Insulin and leptin were found to have strong positive correlation with BMI and other indices of obesity. Serum leptin was also found to be positively correlated with FPG and HbA1c upto a certain limit, but HbA1c went beyond 10%; serum leptin concentration tended to be declined. Serum leptin and Insulin showed strong positive correlation to each other’s. Thyroid hormones and TSH were re-analyzed and its relationship to FPG, HbA1c, fasting serum Insulin and Leptin were explored. Fasting serum Insulin and Leptin showed no significant differences among the different thyroid hormones groups. Conclusion: Uncontrolled type2 diabetes mellitus is associated with alteration of thyroid hormone pictures particularly affecting TT3, FT3 and TSH. This biochemical feature is more evident if the BMI of the Diabetic subjects is low or within the normal range and also the more worsening the glycemic status, there were more deteriorating serum thyroid hormone pictures. Serum leptin was not found to have any relation with these changes.