Incretin Hormones and Insulin Responses During OGTT in Newly Diagnosed T2DM Patients

Abstract

Several research groups have reported variable results about incretin effects of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1(GLP-1) particularly, as well as cytokines balance in type 2 diabetes mellitus (T2DM). The present case-control prospective interventional study was conducted in 2014-2015 at Medical College for Women & Hospital, Dhaka, investigating responses of incretin hormones and insulin to oral glucose tolerance test (OGTT) in Bangladeshi subjects. Blood samples were collected from 36 OGTT positive adult T2DM patients (Pt) and 30 normal adults (NC) at '0' minute (fasting) and at 2 hours after OGTT. Routine laboratory investigations in blood were done and special parameters in serum, i.e. insulin, HGH, TSH, GIP and GLP-1 were analyzed using enzyme immunoassay kits. Pt had FBG and BG2Hr levels much higher than NC (p<0.001). In Pt, F-Insulin and Insulin2Hr were much lower than NC subjects (p<0.001), although Insulin2Hr level was higher than F-Insulin level in Pt. F-GIP (p=0.309) and F-GLP-1(p=0.984) levels were similar between Pt and NC. Interestingly, NC responded to OGTT by increasing GIP2Hr and GLP-1,2Hr levels about 3 times, whereas Pt responded by raising about 1.5 times only compared to F-GIP and F-GLP-1 (p< 0.001). Reduced insulin levels, both fasting and postprandial, were possibly due to decreased responses of GIP and GLP-1 to glucose load in T2DM patients. Further studies with a larger sample size including cytokines are warranted.

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

“…In cases, F-GIP and F-GLP-1 levels were also raised responding to OGTT but by about 1.5 times (p<0.001). We reported previously that in these T2DM patients (case), F-Insulin (p<0.001) and insulin 2HA (p<0.001) were much lower than control subjects, although insulin 2HrA level was higher than F-Insulin level in cases (p<0.001) which were reported previously 24 .…”

“…Interestingly, control subjects responded to OGTT by increasing GIP2Hr and GLP-1, 2Hr levels about 3 times compared to F-GIP and F-GLP-1 (p<0.001) and in cases, F-GIP and F-GLP-1 levels were also raised responding to OGTT but by about 1.5 times only (p<0.001) ( Table-IV, Table-V). In these T2DM patients (cases), F-Insulin (p<0.001) and Insulin 2Hr (p<0.001) were much lower than controls, although Insulin 2Hr level was higher than F-Insulin level in cases (p<0.001) which we reported previously 24 .…”

“…The reason for normal TSH and hGH levels may be due to the fact that our patient group was small in number and were newly diagnosed T2DM with short duration. But responses of GIP and GLP-1 to glucose load were decreased leading to reduced insulin levels in these T2DM patients reported earlier 24 .…”

“…The methodologies of this case-control prospective interventional study were reported in our recently published article 24 . This study was conducted during the period from November 2013 to June 2014 at the Medical Research Unit (MRU), Medical and Health Welfare Trust (MHWT), Uttara, Dhaka, Bangladesh with a research grant obtained from the Ministry of Science and Technology (MOST), Dhaka, Bangladesh.…”

“…Thus, we investigated serum incretin hormones (GIP, GLP-1), TSH and hGH and insulin status and their responses to oral glucose load (OGTT) in Bangladeshi T2DM patients and healthy control subjects in the present case-control prospective interventional study. The results on incretin hormones and insulin responses in these patients have been published recently 24 . In the present article, we have therefore reported the results of our study on the incretin hormones (GIP, GLP-1), TSH status and hGH level and their responses to OGTT in our newly diagnosed Bangladeshi T2DM patients comparing with normal control subjects.…”