Normal Oral Glucose Tolerance Test Results Research Articles

Endothelial Dysfunction Is Associated with Decreased Nitric Oxide Bioavailability in Dysglycaemic Subjects and First-Degree Relatives of Type 2 Diabetic Patients.

Oxidative stress plays an important role in the pathogenesis of diabetes. We investigated oxidative stress and nitrite/nitrate concentrations at baseline and during postprandial hyperglycaemia in 40 first-degree relatives (FDRs) of diabetic patients with normal oral glucose tolerance test (OGTT) results, 40 subjects with abnormal OGTT results (dysglycaemic) and 20 subjects with normal OGTT results (normoglycaemic). Malondialdehyde (MDA), protein carbonyls (PCs), nitrite/nitrate plasma levels, the perfused boundary region (PBR—Glycocheck) of the sublingual microvessels, a marker of glycocalyx integrity, coronary flow reserve (CFR) and left ventricular global longitudinal strain (GLS) were assessed at 0 and 120 min of the OGTT. Insulin sensitivity was evaluated using Matsuda and the insulin sensitivity index (ISI). In all subjects, there were no significant changes in MDA or PC after the OGTT (p > 0.05). Compared with normoglycaemic subjects, FDRs and dysglycaemic subjects had significantly decreased nitrite/nitrate levels (−3% vs. −24% vs. −30%, respectively), an increased PBR and reduced CFR and GLS at 120 min (p < 0.05). The percent reduction in nitrite/nitrate was associated with abnormal Matsuda and ISI results, reversely related with the percent increase in PBR (r = −0.60) and positively related with the percent decrease in CFR (r = 0.39) and GLS (r = 0.48) (p < 0.05). Insulin resistance is associated with reduced nitric oxide bioavailability and coronary and myocardial dysfunction in FDRs and dysglycaemic subjects.

Clinical implications of the 100-g oral glucose tolerance test in the third trimester.

The clinical implications of gestational diabetes mellitus (GDM) diagnosed in the third trimester are not well established and controversy continues regarding the performance of diagnostic tests beyond 28-week gestation. This study aimed to evaluate the incidence of abnormal third trimester oral glucose tolerance test (OGTT) results in women at high risk and to compare the obstetric and neonatal outcomes with those of women with normal OGTT results. The study included 372 women who completed late (>29weeks) 100-g OGTT due to suspected fetal macrosomia, polyhydramnios or a personal risk factor for GDM, diagnosed according to the Carpenter & Coustan criteria. Women withonly one abnormal OGTT value were diagnosed with GDM by abnormal glucose follow-up and analyzed separately. Obstetric and neonatal outcomes were compared between the GDM and the non-GDM groups. GDM was diagnosed in 85/372 (22%) women, including 35 (59.3%) women with one abnormal OGTT value who were later diagnosed with GDM. Of 200 women who had a normal 1-h 50-g glucose challenge test at 24-28weeks, late GDM was diagnosed in 33 (16.5%). Seventy-six (89.5%) of those with GDM were treated by dietary therapy and 9 (10.5%) by pharmacological therapy. Among women with GDM, large-for-gestational-age fetuses, labor induction and elective cesarean section were more prevalent than for those without GDM. Significant differences were not found between the groups in macrosomia and neonatal outcomes. The performance of OGTT in women with risk factors during the third trimester should be considered following further prospective trials.

Hypoglycaemia on an oral glucose tolerance test in pregnancy – Is it clinically significant?

AimDuring pregnancy, some women have a low glucose level on the 75 g oral glucose tolerance test (OGTT). The implications of this are unclear and there is no guideline on how to manage these women. MethodWe recruited pregnant women with a glucose level <3.5 mmol/L at 1- or 2-h during a screening antenatal OGTT. These women (Group 1) underwent self-monitoring of blood glucose (SMBG) over a two-week period. We also compared Group 1′s demographic and pregnancy outcomes data with women who had normal OGTT results (Group 2) and women diagnosed with gestational diabetes mellitus (GDM) (Group 3). Results52 women were recruited. Post-hoc analysis of the SMBG results revealed 50% of women experienced 2 or more elevated fasting BGLs (>5.1 mmol/L) in a week when using the Australian Diabetes in Pregnancy Society (ADIPS) criteria. A further 8% women had elevated 2-h glucose levels (above 6.7 mmol/L). Group 1 women tended to have higher booking weight. They were less likely to have a history of macrosomia or be of East or South-East Asian ethnicity. There were no differences in pregnancy outcomes between Groups 1 and 2, but Group 1 had a higher rate of congenital abnormality (6%) than Group 3 (2%). ConclusionA large proportion of pregnant women who had a low glucose level on OGTT had elevated glucose levels on SMBG, however their pregnancy outcomes were not significantly different to women who had a normal OGTT. Currently there is not enough evidence to advocate routine SMBG and treatment for this group of women.

Influence of medical nutrition therapy on borderline glucose intolerance in pregnant Taiwanese women

Objective: To investigate the influence of medical nutrition therapy (MNT) on borderline glucose intolerance (BGI) in pregnant Taiwanese women.Methods: A total of 5194 singleton pregnant women were enrolled in this prospective, non-randomized study. The participants were subjected to the 50 g 1-h glucose challenge test (GCT) and 100 g 3-h oral glucose tolerance test (OGTT) to screening gestational diabetes mellitus (GDM). BGI was defined as a positive GCT and normal OGTT results. GDM was defined as a positive GCT and abnormal OGTT results. The women were categorized into the following groups: (1) GCT-negative, n = 3881; (2) BGI with MNT, n = 273; (3) BGI without MNT, n = 712; and (4) GDM, n = 328. Multiple logistic analyses were used to estimate the risks of pregnancy outcomes.Results: The odds ratios (95% confidence interval) for total cesareans, third- or fourth-degree perineal lacerations, gestational hypertension or preeclampsia and macrosomia were 1.24 (1.04–1.49), 1.55 (1.06–1.28), 1.78 (1.21–2.61) and 2.50 (1.28–4.91) in the BGI without MNT group compared to the GCT-negative group. There was no difference between BGI with MNT and GCT-negative groups.Conclusions: Women with BGI who did not receive MNT had increased risks of adverse pregnancy outcomes, whereas who received MNT had no different risk with GCT-negative women.

Difference between 2 h and 3 h 75 g glucose tolerance test in the diagnosis of gestational diabetes mellitus (GDM): Results from a national survey on prevalence of GDM

The possibility of the 2 h oral glucose tolerance test (OGTT) as an alternative to the 3 h OGTT was investigated based on data from a national survey on pregnancy-associated diabetes. Data were retrieved from 4179 pregnant women who had OGTT performed after an abnormal 50 g glucose challenge test (GCT). All of the 4 glucose levels during their OGTT were collected and analyzed. According to American Diabetes Association (ADA) gestational diabetes mellitus (GDM) diagnostic criteria, among the 4179 pregnant women who required OGTT, 3429 (82.1%) were normal and 750 (17.9%) were diagnosed as GDM. If the 3rd h glucose levels were omitted from OGTT, 79 cases of GDM (10.5%) would be overlooked. No trend was shown where women with more risk factors were more likely to be overlooked if the 3rd h test was omitted (χ2 for trend=0.038, P>0.05). No significant differences were found in the rate of cesarean section (CS), preterm births or macrosomia between the 79 cases and those with normal OGTT results and in the gestational weeks when OGTT was performed. It shows that in order to diagnose one woman with GDM, another 52 pregnant women would have an innocent 3rd h glucose test. Omission of the 3rd h glucose test in OGTT might be reasonable due to its convenience, better compliance and a small number of possibly miss-diagnosed cases, and their pregnancy outcomes have no significant difference from those of normal pregnant women.

Prepregnancy Overweight and Gestational Diabetes as Determinants of Subsequent Diabetes and Hypertension After 20-Year Follow-Up

The prevalence of overweight or obesity and gestational diabetes mellitus (GDM) is increasing and is a major public health concern. Maternal risk factors for development of diabetes in later life include GDM and overweight during pregnancy. Overweight is a strong risk factor for GDM, and the occurrence of both increases the risk for subsequent metabolic syndrome. Little data are available on the risk of diabetes and metabolic diseases in women with normal glucose tolerance during pregnancy, who have risk factors for GDM. Moreover, few studies have investigated the individual contribution of overweight and GDM during pregnancy to the risk of diabetes and hypertension in later life. This prospective population-based study evaluated prepregnancy overweight and GDM as determinants of risk for diabetes and hypertension, separately and in combination, 20 years after pregnancy. Population-based cohort data from the Northern Finland Birth Cohort 1986 were linked with register-based data on diagnosis of diabetes and hypertension obtained from records on reimbursement of medical expenses and diagnoses at hospital discharge. The oral glucose tolerance test (OGTT) was used to diagnose GDM. Several categories of risk were evaluated for diabetes and hypertension (which were the primary study outcomes). These included: (1) normal weight women with GDM (n = 70); (2) overweight women with GDM (n = 54); (3) normal-weight (n = 768); (4) overweight (n = 250) women with risk factors for GDM but normal OGTT results; and (5) women with no risk factors for GDM (n = 5341). Calculation of the population-attributable fractions (PAFs) estimated the cumulative incidence of diabetes and hypertension associated with prepregnancy overweight. Analysis of time-to-event curves showed that the cumulative incidence of diabetes and hypertension diagnosed in the whole study population was 1.3% and 7.5%, respectively. Women with concomitant prepregnancy overweight and GDM were at extremely high risk of diabetes (hazard ratio [HR], 47.24; PAF, 15.8%) and hypertension (HR, 9.16; PAF, 4.4%). The occurrence of prepregnancy overweight in women with a normal OGTT during pregnancy was associated with increased risk of diabetes (HR, 12.63; PAF, 22.2%) and hypertension (HR, 2.86; PAF, 6.0%), whereas a finding of GDM only among women with prepregnancy normal weight was associated with increased risk of diabetes (HR, 10.61; PAF, 5.2%) but not hypertension. These findings show that prepregnancy overweight is a critical risk factor for development of diabetes and hypertension 20 years after delivery. Overweight combined with even mild GDM markedly increases the risks of these diseases.

Cystic Fibrosis Related Diabetes Mellitus - Diagnostic and Management Challenges

Cystic fibrosis (CF) is the commonest autosomal recessive condition among Caucasian populations, affecting 1 in 2500 live births. The median age of survival has dramatically improved and will reach 40 years for children born in the 1990s. Complications such as cystic fibrosis related diabetes mellitus (CFRD) develop with age, and the median age at diagnosis is 21 years. The prevalence of CFRD progressively increases from 9% below the age of 10 years to 43% above the age of 30 years, with reported annual age-dependent incidence rates ranging from 4% to 9%. The onset of CFRD is insidious and annual screening using the standard oral glucose tolerance test (OGTT) from the age of 10 years has been recommended. However, OGTT thresholds for the diagnosis of impaired glucose tolerance and CFRD were derived from epidemiological studies of non-CF patients and it is uncertain whether they are appropriate for patients with CF. The ability of OGTT alone to detect early abnormalities in blood glucose regulation has been questioned. Continuous glucose monitoring systems (CGMS) may augment the screening and diagnosis of CFRD, as well as guide and monitor its management. Subcutaneous insulin therapy is currently recommended for the treatment of CFRD. Early use of insulin therapy might improve weight gain and lung function of CF patients, including those with normal OGTT results. It is still not clear when insulin therapy should be started, possibly reflecting the difficulties in detecting early but clinically relevant abnormalities in blood glucose metabolism among CF patients. We review the current evidence which highlight these diagnostic and management challenges in CFRD.

Pancreatic Iron and Pancreatic Function in Thalassemia

Introduction: As patients with thalassemia major survive into middle age and beyond, there is greater need to address endocrine complications such as diabetes mellitus. Pancreatic iron deposition is common in thalassemia major patients and correlates with cardiac iron deposition. However, unlike the heart, endocrine dysfunction may not be completely reversible once functional assays become abnormal. Thus it is imperative to characterize preclinical endocrine markers similar to MRI measurements of cardiac T2*. Our aim of this study was to compare pancreatic R2* (the reciprocal of T2*) measurements with the results of an oral glucose tolerance test (OGTT) to determine the relationship between pancreatic iron and pancreatic dysfunction.Methods: We recruited 19 patients with thalassemia major to participate in a frequently sampled OGTT. Results of the OGTT were graded on NIH criteria: a 2 hour glucose level less than 140 was considered normal; between 140 and 200, impaired glucose tolerance; and greater than 200, diabetes mellitus. Acute Insulin Response (AIR) ws estimated from the OGTT measurements using the technique of Stumvall, et al. [1]. Insulin sensitivity was derived from the reciprocal of HOMA Insulin Resistance metric [2]. Pancreatic, cardiac, and hepatic iron burdens were estimated from MRI iron assessments using previously validated techniques. Where serial MRI measurements were available, we used linear interpolation to approximate the organ iron burden at the time of the OGTT. The remaining 7 patients had an MRI within 0.4 ± 0.3 years of the OGTT. The mean age was 21.9 ± 9.6 years; the mean BMI was 21.7 ± 2.3. All patients were on chronic transfusions and on standard iron chelation for their iron overload. The average pancreas R2* was 292.4 ± 259.4 Hz, cardiac R2* was 84.9 ± 64.0 Hz, and hepatic iron concentration (HIC) was 10.2 ± 10.1 mg/g dry weight. Pancreatic R2* correlated with cardiac R2* (r = 0.61, P = 0.006) in this population.Results: Of the 19 patients enrolled, 4 had diabetes, 4 had impaired glucose tolerance, and the remaining 11 had normal glucose tolerance. Figure 1 shows the expected inverse relationship between AIR and insulin sensitivity for each patient. The product of these two variables is the disposition index (DI) and is used as a measure of beta-cell function. Corresponding log-log fits to the data are shown in the same color and represent isoclines of constant DI. The patients with diabetes mellitus (gray circles) lie on a DI curve closer to the origin than normal (black squares) and glucose intolerant patients (gray triangles); lower DI indicates decreased islet cell mass or function. The patients with impaired glucose tolerance lie on a curve at the lower limit of normal. Figure 2 shows the relationship between pancreatic R2* and DI. The dashed box encloses the upper two tertiles of pancreatic R2* (boundary at 150 Hz). In this group, 7/12 had either impaired glucose tolerance or diabetes mellitus. In contrast, only 1/7 with R2* < 150 Hz had impaired glucose tolerance (p=0.08 by Fisher's exact test). Thus, 7/8 of the patients with impaired glucose tolerance or diabetes had moderate to severe pancreatic iron.Discussion: These data confirm that pancreatic iron deposition and pancreatic dysfunction are common in patients with thalassemia major. However, the relationship between pancreatic iron and function is complicated because of other risk factors such as family history, age, body habitus, as well as the type and pattern of iron chelation therapy. Although most patients with pancreatic dysfunction had moderate to severe pancreatic iron, 5/12 patients with high pancreatic iron had normal OGTT results, not unlike the normal cardiac function observed in many patients with heavy cardiac iron burdens. Serial evaluation is necessary to see if these patients will develop glucose intolerance or diabetes prospectively. Despite the complicated relationship between pancreatic function and iron, increased pancreatic R2* appears to identify a higher risk population that would likely benefit from improved chelation and more frequent endocrine evaluation. [Display omitted] [Display omitted]

Feasibility of diagnosing gestational diabetes mellitus by Oral Glucose Tolerance Test without the third-hour plasma glucose level

目的 研究妊娠期口服葡萄糖耐量试验(oral glucose tolerance test,OGTT)三次取血诊断妊娠期糖尿病(gestational diabetes mellitus,GDM)的可行性.方法对404例50 g葡萄糖负荷试验阳性的孕妇行OGTT检查. 结果以美国糖尿病协会(American Diabetes Association,ADA)标准诊断GDM者111例,葡萄糖耐量受损(impaired glucose tolerance test,IGT)者72例,OGTT正常者221例;若不计服糖后3 h血糖值,则诊断GDM者106例,IGT者71例,漏诊率分别为4.5%和1.4%.6例漏诊孕妇与OGTT正常的50 g GCT阳性的221例孕妇相比,其妊高征、巨大儿、大于胎龄儿和Apgar评分≤3分的发生率差异无统计学意义(16.6%和8.1%、16.6%和6.3%、50.1%和24.4%、0和0.9%,P均＞0.05).结论OGTT三次取血操作次数少、漏诊率低,临床上可作为GDM的诊断标准。

Elevated plasma homocysteine levels in gestational diabetes mellitus

Objective. This prospective study investigated the occurrence of hyperhomocysteinemia in a population of patients with gestational diabetes. The aim was to determine whether elevated plasma homocysteine is associated with gestational diabetes in Turkish women. Study design. This prospective controlled study was conducted in the Department of Obstetrics and Gynecology of the Baskent University Faculty of Medicine between April 2002 and June 2003, and involved 304 Turkish women with uncomplicated pregnancies who were at 24-28 weeks gestation. The women in the study were assigned to one of three groups according to the results of the 50-g glucose screening and the oral glucose tolerance test (OGTT): group 1 comprised women who had normal glucose levels (≤ 135 mg/dL) after the 50-g challenge; group 2 comprised women with abnormal screening test results (> 135 mg/dL) but normal OGTT results; and group 3 comprised patients with gestational diabetes mellitus (GDM) according to the OGTT. Levels of fasting glucose...

Elevated plasma homocysteine levels in gestational diabetes mellitus.

This prospective study investigated the occurrence of hyperhomocysteinemia in a population of patients with gestational diabetes. The aim was to determine whether elevated plasma homocysteine is associated with gestational diabetes in Turkish women. This prospective controlled study was conducted in the Department of Obstetrics and Gynecology of the Baskent University Faculty of Medicine between April 2002 and June 2003, and involved 304 Turkish women with uncomplicated pregnancies who were at 24-28 weeks gestation. The women in the study were assigned to one of three groups according to the results of the 50-g glucose screening and the oral glucose tolerance test (OGTT): group 1 comprised women who had normal glucose levels (< or = 135 mg/dL) after the 50-g challenge; group 2 comprised women with abnormal screening test results (> 135 mg/dL) but normal OGTT results; and group 3 comprised patients with gestational diabetes mellitus (GDM) according to the OGTT. Levels of fasting glucose, homocysteine, vitamin B(12) and folic acid, total cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol levels were measured in the three groups. Levels of insulin sensitivity were calculated using the homeostasis model assessment (HOMA) formula. The mean level of homocysteine in group 1 was significantly lower than the levels in groups 2 and 3 (p < 0.001) The mean triglyceride and VLDL levels in group 3 were significantly higher than the corresponding levels in group 1 (p < 0.05 for both). There were no significant differences among the groups with respect to levels of total cholesterol, vitamin B(12), folic acid, creatinine, fasting glucose or insulin. The mean HOMA value in group 3 was significantly higher than that in group 1 (p < 0.05). Only the blood glucose level after the 50-g glucose screening [p = 0.000, 95% confidence interval (CI) 0.009-0.027] had a significant correlation with homocysteine levels. In this prospective study of Turkish women, we found that patients with gestational diabetes and women with abnormal screening test results (> 135 mg/dL) but normal OGTT results have higher homocysteine levels than normal pregnant women. This increased level seems to be related to an abnormal 50-g test but not to insulin resistance. Further investigations are needed to follow up for these patients in the postpartum period and later in their life.

Gestational Diabetes mellitus and Neonatal Hyperthyrotropinemia

Objective: To determine whether gestational diabetes mellitus (GDM) is associated with increased incidence of neonatal hyperthyrotropinemia. Study Design: In a retrospective study, maternal characteristics, infant outcome and cord blood thyrotropin (TSH) concentration were compared between 469 diet-treated GDM pregnancies diagnosed by the World Health Organization 75 g oral glucose tolerance test (OGTT) with 474 non-diabetic pregnancies with normal OGTT results. Results: Hyperthyrotropinemia (TSH >16 mIU/l) was found in 7.2% of the GDM pregnancies and 2.1% of the controls (p < 0.001), but there was no difference in the birth weight or gestational age. The TSH concentration was correlated with the OGTT 2-hour glucose value (ρ = 0.0948, p = 0.029) and Apgar score at the fifth minute (ρ = –0.1197, p = 0.009). There was no difference in the TSH or free thyroxine concentrations between the hyperthyrotropinemic newborns of the GDM and control groups. In the GDM group, the hyperthyrotropinemic newborns had a higher incidence (p = 0.017) of neonatal jaundice. Conclusions: Neonatal hyperthyrotropinemia is more frequently found in pregnancies with GDM, and this could have reflected increased fetal in-utero hypoxic stress in these pregnancies.

Insulin action enhancement normalizes brachial artery vasoactivity in patients with peripheral vascular disease and occult diabetes

Purpose: Brachial artery vasoactivity (BAVA) evaluation is a reliable, noninvasive method of assessing arterial endothelial function in vivo. We previously have shown that patients with peripheral vascular disease (PVD) and occult diabetes have abnormal BAVA results when fasting and after oral glucose intake during oral glucose tolerance test (OGTT). Troglitazone is an oral hypoglycemic agent that enhances the action of insulin. The effect of troglitazone on BAVA in patients with occult diabetes and PVD is not known. Methods: Patients with PVD, normal fasting glucose levels, and abnormal OGTT results were identified. With a duplex ultrasound scan, BAVA was evaluated by measuring the brachial artery (BA) flow (in millimeters per minute) before and after 5 minutes of BA occlusion during fasting and at 30 minutes, 1 hour, and 2 hours after the administration of 75 g of glucose during OGTT. Troglitazone therapy (400 mg/day) was begun, and the BAVA evaluation was repeated after 2 and 4 months. These results were compared with the results of the control group who had normal fasting glucose levels, normal OGTT results, and no evidence of PVD. A paired t test was used to compare the BA flow before and after BA occlusion, with a P value of less than .05 considered significant. Results: The control group had a normal hyperemic response with a significantly increased BA flow after 5 minutes of BA occlusion during fasting and at all stages of the OGTT. The occult diabetic group had an abnormal response to hyperemia before the treatment with troglitazone and showed little change in flow after BA occlusion. After 2 months of troglitazone therapy, BAVA results improved after oral glucose intake but not during fasting. After 4 months, BAVA results normalized both while fasting and after oral glucose intake during the OGTT. Conclusion: Patients with occult diabetes and PVD have impaired BAVA, which normalizes after treatment with troglitazone. Insulin-action enhancers may slow the progression of PVD in patients with diabetes by improving endothelial cell function. Agents that are aimed at enhancing the action of insulin may have an advantage over the other traditional therapies for diabetes. (J Vasc Surg 1998;28:1024-32.)

Lower prevalence of impaired glucose tolerance and diabetes associated with daily seal oil or salmon consumption among Alaska Natives.

To examine the association of seal oil and salmon consumption with impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) among Alaska Natives. Screening was performed on 666 Yup'ik Eskimos and Athabaskan Indians > or = 40 years old in 15 villages. Self-administered questionnaires were used to obtain partial food frequency data. A case was defined as IGT or NIDDM, either newly discovered or known. Newly discovered cases (11 patients with NIDDM and 17 with IGT) were determined by random blood glucose testing followed by a 2-h 75-g oral glucose tolerance test (OGTT) for those with values > or = 6.72 mmol/l or for subjects with unconfirmed histories of glucose intolerance. Known cases included 26 patients with NIDDM and 1 with IGT. Control subjects had random blood glucoses < 6.72 or normal OGTT results. Compared with less-than-daily consumption, both daily seal oil (odds ratio [OR] 0.2, 95% confidence interval [CI] 0.1-0.8) and daily salmon consumption (OR 0.5, CI 0.2-1.1) were associated with a lower prevalence of glucose intolerance, controlling for age, ethnicity, body mass index, and sex. The effects were similar when limited to newly discovered cases: OR 0.3, CI 0.1-1.3 for seal oil and OR 0.4, CI 0.1-1.3 for salmon. Consumption of seal oil at least five times per week was required to reduce risk. Consumption of seal oil and salmon, high in omega-3 fatty acids, appears to lower the risk of glucose intolerance and is a potentially modifiable risk factor for NIDDM in Alaska Natives.