Insulin Secretion During Oral Glucose Tolerance Test In Women With Impaired Glucose Tolerance

Gestational glucose intolerance includes Gestational Impaired Glucose Tolerance and Gestational Diabetes Mellitus. About the outbreak principle of gestational diabetes mellitus, it has not definitely clear-cut yet. So far the outbreak principles which have been identified by most scholars are insulin resistance (IR) and the declined functions of insulin (3-cell. During normal gestation, the pregnant women have increased insulin resistance function and their liver, flesh and adipose tissue's sensibility for insulin will decrease. Especially in later half of gestation, their sensibility for insulin will go down distinctly by 45%-80%.The research states clearly that with the progress of gravidity, the amount of insulin secretion will increase by 2-3 times. According to the results of vein glucose tolerance test which is conducted during the latter half of gestation, compared with non-pregnant women, the first and second time phrase that are secreted by glucose's stimulating insulin will increase 60% and 130%respectively. The increase of insulin level is a kind of adaptive compensatory mechanism by growing the quantity to make up the decreased sensibility. During the gravidity, the factors for strengthening the function of the anti-insulin come from 5 kinds of anti-insulin hormone which are: glucocorticoid, progesterone, human placental lactogen (HPL), prolactin and estrogen.The researchers such as Gorgino reported that if we use excessive glucocorticoids to deal with skeletal muscle, insulin receptor's tyrosine phosphorylation will decline, then the content of the receptor substrate-1 will be reduced. Accordingly speculate. insulin resistance caused by glucocorticoid will find expression in insulin receptor aspect. The researchers such as Picard used progesterone receptor antagonist and found that the female rat's fasting blood-glucose would lower, at the same time the insulin to glucose's stimulus-response level would rise, the female rate's islet cells would become bigger and they would secrete more insulin. All of these show that the progesterone can affect insulin's release and the pancreas'functions. Human placental lactogen has the functions of promoting adipose to dissolve, leading non-esterified fatty acid to increase, controlling the surrounding glucose to intake and restraining neoglycogenesis. In pregnancy duration,the density of serocym prolactin will increase by 5-10 times. The estrogen can stimulate liver to produce cortisone combining globulin. When globulin increases, the pregnant women's suprarene will secrete more cortisone to satisfy globulin's need for combining, and at the same time, the volume of the dissociated cortisone will take part in insulin resistance of gestation period indirectly.There are also other scholars have the idea that during the gestation the declining of the insulin secretion compensation is another reason for abnormal glucose metabolism. The single insulin resistance is not the only reason for abnormal glucose metabolism. In both mid and late gestation period, the insulin antagonist will increase, but there are only 5% may develop into gestational diabetes mellitus (GDM). And the women with abnormal glucose metabolism will have insulin resistance (IR), except for this, the insulin secretion may also have drawbacks. The researchers like C. Ouyang Fengxiu adopted the method of HOMA to calculate NGT, GIGT, GDM patient's HOMA-IR in their late pregnancy and their HOMA-B and to estimate IR and the isletβcell's secretion function. It turns out that from NGT to GDM, HOMA-IR is increasing progressively, and however. HOMA-B is decreasing successively. Comparing GDM and NGT, we can know that ability of continuous insulin secretion drops off. Even though there are lots of research about pathogeny of GDM and its risk factors, the pathogeny has not been clear-cut. And the reports about insulin's absolute quantity are different. The thesis assays the changes of GDM patients'insulin levels, providing evidences for the changes of insulin absolute quantity in gestation period.Study objective:Look into the changes of insulin level in glucose tolerance test of pregnant women who have the abnormal glucose metabolism. Make clear the etiology of GIGR and find out the relationship between Maternal Weight, family history and GIGR disease, providing evidences for the cure of GIGR.Study methods:Choose pregnant women who are at 24-28 weeks of gestation from the ones who come to Women's Hospital of School of Medicine of Zhejiang University to take perinatal health care and parturition during the period from January of 2008 to October of 2009. For this group of women, I take Oral glucose Screening Experiment by 50g. If an exception rises, take OGTT by 75g. In total,75 women whose glucose metabolism is anomalous are found. At the same time, take 50 pregnant women at random as a control group, and these women take normal glucose screening experiment by 50g. From this group, I take venous blood in separate 4 moments:on an empty stomach; one, two and three hours after taking 75g glucose respectively. And test the blood sugar and insulin levels of the 4 moments separately, and then make comparison. At the same time, analyze the relationship between their family history and GIGR.Results:1. According to the experiment, in the group with abnormal glucose tolerance, the levels of insulin measured at one hour after meal (123.5±34.1mU/L) and 2 hours after meal (78.8±23.6mU/L) are much higher than that of the normal group (one hour after meal:48.6±11.2mU/L P<0.05, and 2 hours after meal:27.5±8.4mU/L P<0.05). However, even though the insulin levels measured on an empty stomach and at the moment of 3 hours after meal are also higher than that of the normal group, the data can not reach the statistical significance.2. About the results of the HOMA-IR, the normal group is=2.4±0.5, and that of the group with GIGR is=5.2±1.3. The latter is much higher than the former. There is obvious difference between them (P<0.05).3. In glucose tolerance experiment, the group of pregnant women who are with GIGT and family history have more blood sugar than those who do not have family history. The data of the former group are:on empty stomach 5.6±1.3mmol, and 3 hours after meal 6.8±1.8mmol. The data of the latter group are:on empty stomach 5.3±1.9mmol P<0.01, and 3 hours after meal 6.3±1.8mmol P<0.05. However, the data on the moment of 1 hour and 3 hours after meal have no obvious difference between the two groups.4. In glucose tolerance experiment, the group of pregnant women who are with GIGT and family history have higher insulin level than those who do not have family history. The data of the former group are:on empty stomach 9.1±2.4mU/L,1 hour after meal 130.1±32.9mU/L,2 hours after meal 85.5±26.5mU/L and 3 hours after meal 28.8±6.9mU/L. The data of the latter group are:on empty stomach 7.3±3.3mU/L P<0.05,1 hour after meal 118.5±39.8mU/L P<0.01,2 hours after meal 73.9±28.6mU/L P<0.01, and 3 hours after meal 16.7±4.9mU/L P<0.01. in particular, the difference of insulin level after meal is more obvious.5. There is no obvious difference between the pregnant women with GIGR and normal ones in terms of age and gestational weeks. But in terms of pre-pregnancy weight index (24.1±4.3kg/m2 VS 22.1±2.1kg/m2, P<0.05), the amounts of weight gain in gestational period (13.5±3.5kg VS 8.1±1.2kg, P<0.05) and family history positive ratio (41/75 VS 11/50, P<0.05), the differences are significant. 6. the pregnant week when the pregnant women with family history are diagnosed as abnormal glucose tolerance (26.8±4.1 weeks) is earlier than that of ones without family history (28.8±4.1 weeks P<0.05). The results of 50g of glucose screening test for women with family history (9.8±1.9mmol/L) is also higher than that of the group without family history (9.8±1.9mmol/L P<0.01). However, their difference of glycolated hemoglobin is not significant.Conclusion:The pregnant women with anomalous glucose metabolism will secrete more insulin, and the index of HOMA-IR will rise. This shows that the women with anomalous glucose metabolism hold insulin resistance; thereby hyperinsulinemia would appear to keep normal blood sugar level. Pre-pregnancy obesity and excessive weight gain are risk factors of anomalous glucose metabolism. Anomalous glucose metabolism and family history are closely related. The pregnant women with family history have higher occurrence of attack and the onset time will be advanced.