Incretin Hormones, Thyroid Stimulating Hormone and Human Growth Hormone Responses During Ogtt in Newly Diagnosed T2DM Patients

Several research groups have reported variable results about incretin effects of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1(GLP-1), altered thyroid stimulating hormone (TSH) status, human growth hormone (hGH) deficiency and perturbed cytokines balances in type 2 diabetes mellitus (T2DM).The present case-control prospective interventional study was conducted investigating responses of incretin hormones (GIP, GLP-1), TSH and hGH to oral glucose tolerance test (OGTT) in newly diagnosed Bangladeshi T2DM patient. Blood samples were collected from 36 OGTT positive newly diagnosed T2DM patients as cases and 30 normal adults as controls at '0' minute (fasting) and at 2 hours after OGTT. Laboratory investigations were done and special parameters in serum, i.e. hGH, TSH, Insulin, GIP and GLP-1 were analyzed using enzyme immunoassay (EIA) kits. Statistical analyses were made by Student's 't' test using SPSS programm. T2DM patients (cases) had FBG and BG2Hr levels much higher than controls (p<0.001). No significant differences were observed between controls and cases for F-TSH (p=0.927), TSH2HrA (p=0.413), F-hGH (p=0.532) and hGH2HrA (p=0.773) levels. It was observed that F-GIP (p=0.309) and F-GLP-1 (p=0.984) levels were similar between cases and controls. Interestingly, control subjects responded to OGTT by increasing GIP2HA and GLP-1, 2HR levels about 3 times compared to F-GIP and F-GLP-1 (p<0.001). In cases, F-GIP and F-GLP-1 levels were also raised responding to OGTT but by about 1.5 times only compared to F-GIP and F-GLP-1 (p<0.025). Although no significant differences were observed for F-TSH, TSH2HrA, F-hGH and hGH2HrA between cases and controls, F-GIP and F-GLP-1 levels were raised responding to OGTT in cases by about 1.5 times only compared to about 3.0 times in controls subjects. But responses of GIP and GLP-1 to glucose load were lower leading to reduced insulin levels in these T2DM patients reported earlier. Further studies with a larger sample size including cytokines are warranted. Bangladesh J Med Biochem 2018; 11(1): 9-16