The oral glucose tolerance test (OGTT) revisited

Improving Detection of Prediabetes in Children and Adults: Using Combinations of Blood Glucose Tests

Highlights

Aim

To determine combinations of blood glucose tests: oral glucose tolerance (OGT), fasting plasma glucose (FPG), and hemoglobin A1C (HbA1C) that are associated with highest diagnostic rates of prediabetes in non-diabetic American children and adults.

Methods

The 2007–2008 U.S. National Health and Nutrition Examination Surveys data were used for this study. Overall and specific prevalence of prediabetes (defined using OGT + FPG, OGT + HbA1C, HbA1C + FPG, and OGT + FPG + HbA1C tests) were determined across age, race/ethnicity, sex, and BMI categories.

Results

FPG + HbA1C test was associated with significantly higher diagnostic rates of prediabetes across age, race/ethnicity, and BMI. Estimates of overall prevalence of prediabetes using OGT + FPG, OGT + HbA1C, HbA1C + FPG, and OGT + FPG + HbA1C tests were 20.3, 24.2, 33, and 34.3%, respectively. Compared to OGT + FPG, the use of HbA1C + FPG test in screening was associated with 44.8, 135, 38.6, and 35.9% increased prevalence of prediabetes in non-Hispanic White, non-Hispanic Black, Mexican-American, and other racial/ethnic men, respectively. The corresponding values in women were 67.8, 140, 37.2, and 42.6%, respectively. Combined use of all blood glucose tests did not improve the overall and gender-specific prediabetes prevalence beyond what was observed using HbA1C + FPG test.

Conclusion

HbA1C criteria were associated with higher diagnosis rates of prediabetes than FPG and OGT tests in non-diabetic American children and adults. Using a combination of HbA1C and FPG test in screening for prediabetes reduces intrinsic systematic bias in using just HbA1C testing and offers the benefits of each test. A well-defined HbA1C that takes into consideration race/ethnicity, gender, age, and body mass index may improve detection of prediabetes in population and clinical settings.

Biological diagnosis of diabetes mellitus

Diabetes mellitus is a common disease whose complications are severe. For decades, the diagnosis of diabetes and prediabetes was using only fasting glucose or glucose two hours during an oral glucose tolerance test. Recently, it is possible to use HbA1c. Each of these tests has advantages and limitations that must be well known by clinicians for better care for patients. So they could use one, two or three of this tests to reach to a proper diagnosis. The aim of this article is about the strong and weak points of these tests.

Diagnostic tools for post-gastric bypass hypoglycaemia

In spite of its evident success, several late complications can occur after gastric bypass surgery. One of these is post-gastric bypass hypoglycaemia. No evidence-based guidelines exist in the literature on how to confirm the presence of this syndrome. This study aims to describe and compare the tests aimed at making a diagnosis of post-gastric bypass hypoglycaemia and to provide a diagnostic approach based upon the available evidence. A search was conducted in PubMed, Cochrane and Embase. A few questionnaires have been developed to measure the severity of symptoms in post-gastric bypass hypoglycaemia but none has been validated. The gold standard for provocation of a hypoglycaemic event is the oral glucose tolerance test or the liquid mixed meal tolerance test. Both show a high prevalence of hypoglycaemia in post-gastric bypass patients with and without hypoglycaemic complaints as well as in healthy volunteers. No uniformly established cut-off values for glucose concentrations are defined in the literature for the diagnosis of post-gastric bypass hypoglycaemia. For establishing an accurate diagnosis of post-gastric bypass hypoglycaemia, a validated questionnaire, in connection with the diagnostic performance of provocation tests, is the most important thing missing. Given these shortcomings, we provide recommendations based upon the current literature.

Effects of telephone-delivered lifestyle support on the development of diabetes in participants at high risk of type 2 diabetes: J-DOIT1, a pragmatic cluster randomised trial

OBJECTIVES

To examine the effects of telephone-delivered lifestyle coaching on preventing the development of type 2 diabetes mellitus (T2DM) in participants with impaired fasting glucose (IFG).

DESIGN

Cluster randomised trial.

SETTING

40 groups from 17 healthcare divisions in Japan: companies (31), communities (6) and mixed settings (3).

PARTICIPANTS

Participants aged 20-65 years with fasting plasma glucose (FPG) of 5.6-6.9 mmol/L were invited from the 17 healthcare divisions.

RANDOMISATION

The groups were then randomly assigned to an intervention or a control arm by independent statisticians according to a computer-generated list.

INTERVENTION

The intervention arm received a 1-year telephone-delivered intervention provided by three private lifestyle support centres (at different frequencies: low-frequency (3 times), middle-frequency (6 times) and high-frequency (10 times) support calls). The intervention and control arms both received self-help devices such as a weight scale and pedometer.

OUTCOMES

Participants were followed up using data from annual health check-ups and a questionnaire regarding lifestyle. The primary outcome was the development of T2DM defined as FPG ≥ 7.0 mmol/L, the diagnosis of diabetes, or use of an antidiabetic drug, confirmed by referring to medical cards.

RESULTS

Of 14,473 screened individuals, participants were enrolled in either the intervention (n = 1240) arm or control (n = 1367) arm. Overall, the HR for the development of T2DM in the intervention arm during 5.5 years was 1.00 (95% CI 0.74 to 1.34). In the subanalysis, the HR was 0.59 (95% CI 0.42 to 0.83) in the subgroup that received phone calls the most frequently, compared with the control arm. A limitation of the study includes a lack of blinding.

CONCLUSIONS

High-frequency telephone-delivered lifestyle support could effectively prevent T2DM in participants with IFG in a primary healthcare setting, although low-frequency and middle-frequency phone calls did not.

TRIAL REGISTRATION NUMBER

This trial has been registered with the University Hospital Medical Information Network (UMIN000000662).

Preparation and characterization of glycoprotein-resistant starch complex as a coating material for oral bioadhesive microparticles for colon-targeted polypeptide delivery

For effective oral delivery of polypeptide or protein and enhancement their oral bioavailability, a new resistant starch-glycoprotein complex bioadhesive carrier and an oral colon-targeted bioadhesive delivery microparticle system were developed. A glycoprotein, concanavalin A (Con A), was successfully conjugated to the molecules of resistant starch acetate (RSA), leading to the formation of resistant starch-glycoprotein complex. This Con A-conjugated RSA film as a coating material showed an excellent controlled-release property. In streptozotocin (STZ)-induced type II diabetic rats, the insulin-loaded microparticles coated with this Con A-conjugated RSA film exhibited good hypoglycemic response for keeping the plasma glucose level within the normal range for totally 44-52 h after oral administration with different insulin dosages. Oral glucose tolerance tests indicated that successive oral administration of these colon-targeted bioadhesive microparticles with insulin at a level of 50 IU/kg could achieve a hypoglycemic effect similar to that by injection of insulin at 35 IU/kg. Therefore, the potential of this new Con A-conjugated RSA film-coated microparticle system has been demonstrated to be capable of improving the oral bioavailability of bioactive proteins and peptides.

Phenotypic flexibility as a measure of health: the optimal nutritional stress response test

Nutrition research is struggling to demonstrate beneficial health effects, since nutritional effects are often subtle and long term. Health has been redefined as the ability of our body to cope with daily-life challenges. Physiology acts as a well-orchestrated machinery to adapt to the continuously changing environment. We term this adaptive capacity “phenotypic flexibility.” The phenotypic flexibility concept implies that health can be measured by the ability to adapt to conditions of temporary stress, such as physical exercise, infections or mental stress, in a healthy manner. This may offer a more sensitive way to assess changes in health status of healthy subjects. Here, we performed a systematic review of 61 studies applying different nutritional stress tests to quantify health and nutritional health effects, with the objective to define an optimal nutritional stress test that has the potential to be adopted as the golden standard in nutrition research. To acknowledge the multi-target role of nutrition, a relevant subset of 50 processes that govern optimal health, with high relevance to diet, was used to define phenotypic flexibility. Subsequently, we assessed the response of biomarkers related to this subset of processes to the different challenge tests. Based on the obtained insights, we propose a nutritional stress test composed of a high-fat, high-caloric drink, containing 60 g palm olein, 75 g glucose and 20 g dairy protein in a total volume of 400 ml. The use of such a standardized nutritional challenge test in intervention studies is expected to demonstrate subtle improvements of phenotypic flexibility, thereby enabling substantiation of nutritional health effects.

Obstructive sleep apnoea, insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.

Polysaccharides from Enteromorpha prolifera Improve Glucose Metabolism in Diabetic Rats

This study investigated the effects of polysaccharides from Enteromorpha prolifera (PEP) on glucose metabolism in a rat model of diabetes mellitus (DM). PEP (0, 150, 300, and 600 mg/kg) was administered intragastrically to rats for four weeks. After treatment, fasting blood glucose (FBG) and insulin (INS) levels were measured, and the insulin sensitivity index (ISI) was calculated. The morphopathological changes in the pancreas were observed. Serum samples were collected to measure the oxidant-antioxidant status. The mRNA expression levels of glucokinase (GCK) and insulin receptor (InsR) in liver tissue and glucose transporter type 4 (GLUT-4) and adiponectin (APN) in adipose tissue were determined. Compared with the model group, the FBG and INS levels were lower, the ISI was higher, and the number of islet β-cells was significantly increased in all the PEP groups. In the medium- and high-dose PEP groups, MDA levels decreased, and the enzymatic activities of SOD and GSH-Px increased. The mRNA expression of InsR and GCK increased in all the PEP groups; APN mRNA expression increased in the high-dose PEP group, and GLUT-4 mRNA expression increased in adipose tissue. These findings suggest that PEP is a potential therapeutic agent that can be utilized to treat DM.

Effect of Cinnamon Tea on Postprandial Glucose Concentration

Glycaemic control, in particular at postprandial period, has a key role in prevention of different diseases, including diabetes and cardiovascular events. Previous studies suggest that postprandial high blood glucose levels (BGL) can lead to an oxidative stress status, which is associated with metabolic alterations. Cinnamon powder has demonstrated a beneficial effect on postprandial glucose homeostasis in animals and human models. The purpose of this study is to investigate the effect of cinnamon tea (C. burmannii) on postprandial capillary blood glucose level on nondiabetic adults. Participants were given oral glucose tolerance test either with or without cinnamon tea in a randomized clinical trial. The data revealed that cinnamon tea administration slightly decreased postprandial BGL. Cinnamon tea ingestion also results in a significantly lower postprandial maximum glucose concentration and variation of maximum glucose concentration (p < 0.05). Chemical analysis showed that cinnamon tea has a high antioxidant capacity, which may be due to its polyphenol content. The present study provides evidence that cinnamon tea, obtained from C. burmannii, could be beneficial for controlling glucose metabolism in nondiabetic adults during postprandial period.

An evaluation of the effects of the novel antipsychotic drug lurasidone on glucose tolerance and insulin resistance: a comparison with olanzapine

Over the past two decades, there has been a notable rise in the use of antipsychotic drugs, as they are used to treat an increasing number of neuropsychiatric disorders. This rise has been led predominantly by greater use of the second generation antipsychotic (SGA) drugs, which have a low incidence of neurological side-effects. However, many SGAs cause metabolic dysregulation, including glucose intolerance and insulin resistance, thus increasing the risk of cardiometabolic disorders. The metabolic effects of the novel SGA lurasidone, which was approved by the Food and Drug Administration in 2010, remain largely unknown. As rodent models accurately predict the metabolic effects of SGAs in humans, the aim of the present study was to use sophisticated animal models of glucose tolerance and insulin resistance to measure the metabolic effects of lurasidone. In parallel, we compared the SGA olanzapine, which has established metabolic effects. Adult female rats were treated with vehicle, lurasidone (0.2, 0.8 or 2.0 mg/kg, s.c.) or olanzapine (10.0 mg/kg, s.c.) and subjected to the glucose tolerance test (GTT). Separate groups of rats were treated with vehicle, lurasidone (0.2, 0.8 or 2.0 mg/kg, s.c.) or olanzapine (1.5 and 15 mg/kg, s.c.) and tested for insulin resistance with the hyperinsulinemic-euglycemic clamp (HIEC). Compared to vehicle treated animals, lurasidone caused mild glucose intolerance in the GTT with a single dose, but there was no effect on insulin resistance in the GTT, measured by HOMA-IR. The HIEC also confirmed no effect of lurasidone on insulin resistance. In contrast, olanzapine demonstrated dose-dependent and potent glucose intolerance, and insulin resistance in both tests. Thus, in preclinical models, lurasidone demonstrates mild metabolic liability compared to existing SGAs such as olanzapine. However, confirmation of these effects in humans with equivalent tests should be confirmed.

Antidiabetic Effect of Methanolic Extract from Berberis julianae Schneid. via Activation of AMP-Activated Protein Kinase in Type 2 Diabetic Mice

We have investigated the antidiabetic effect and mechanism of methanolic extract of Berberis julianae Schneid. (BJSME) in STZ induced Type 2 diabetes mellitus mice. T2DM mice were induced by high fat diet and low dose streptozotocin (STZ). BJSME was orally administrated at the doses of 60, 120, and 240 mg/kg/d, for 21 days. Metformin was used as positive control drug. Food intake, body weight, plasma glucose, oral glucose tolerance test, insulin tolerance test, insulin, and blood-lipid content were measured. The effects of BJSME on the glucose transporter 4 (GLUT4) translocation in L6 myotubes and the GLUT4 protein expression in skeletal muscle as well as phosphorylation of the AMP-activated protein kinase (AMPK) in liver and muscle were examined. In vitro and in vivo results indicate that BJSME increased GLUT4 translocation by 1.8-fold and BJSME significantly improved the oral glucose tolerance and low density lipoprotein cholesterol (LDL-C) of serum and reduced body weight, glucose, and other related blood-lipid contents. The BJSME treatment also stimulated the phosphorylation of AMPK. Thus, BJSME seems to possess promising beneficial effects for the treatment of T2DM with the possible mechanism via stimulating AMPK activity.

Emerging parameters of the insulin and glucose response on the oral glucose tolerance test: reproducibility and implications for glucose homeostasis in individuals with and without diabetes

AIMS

Recent studies have suggested that novel parameters of the insulin and glucose response on the oral glucose tolerance test (OGTT) can provide metabolic insight beyond glucose tolerance, but have not evaluated their reproducibility. Thus, our aim was to evaluate the reproducibility of these parameters and, if confirmed, characterize their clinical/pathophysiologic relevance in healthy and diabetic individuals.

METHODS

Thirty healthy adults each underwent 3 replicate OGTTs, enabling assessment of the reproducibility of the following 5 parameters: time to insulin peak, shape of the glucose curve, glucose nadir below baseline, 1-h post-challenge glucose, and time to glucose peak. The only reproducible parameter was then further evaluated in 63 patients with early type 2 diabetes (T2DM) before and after 4-weeks of intensive insulin therapy (IIT) designed to improve beta-cell function (measured by Insulin Secretion-Sensitivity-Index-2 (ISSI-2)).

RESULTS

Of the five parameters, only time to glucose peak displayed reliable reproducibility on replicate testing (κ=0.76). Over 80% of controls had their glucose peak at 30-min post-load, whereas all but one of the diabetic patients had their peak at 60-min or later. ISSI-2 was lower in T2DM patients with peak at ≥90-min than in those with peak at ≤60-min (P=0.012). In patients in whom IIT improved beta-cell function by ≥20% from baseline, 39.1% had glucose peak on the post-therapy OGTT shift to an earlier timepoint, as compared to 15.4% with similar shift in those without such improvement(P=0.03).

CONCLUSION

Time to glucose peak is a reproducible characteristic on the OGTT and associated with beta-cell function in early T2DM.

Impaired glucose metabolism in hypertensive patients with/without the metabolic syndrome

BACKGROUND

In hypertension clinics, screening patients for the metabolic syndrome (MetS) is common practice, while performing the cumbersome oral glucose tolerance test (OGTT) is not. How large is the underestimation of diabetes and prediabetes that ensues is unknown.

METHODS

We recruited N=1397 patients with essential arterial hypertension who underwent a 75-g OGTT and were classified as normally glucotolerant (NGT) or having impaired glucose metabolism (IGM), and as affected or not by MetS (ATPIII criteria). The agreement between the OGTT and the ATPIII criteria in attributing a high cardiovascular risk was estimated by matching the categories of MetS and no-MetS with NGT and IGM.

RESULTS

n=677/1397 patients (48%) satisfied criteria for MetS, while n=757/1397 (54%) had an IGM. MetS and IGM were both present in n=512/1397 patients (36.6%), and both absent in n=475/1397 (34%). Further n=410/1397 patients (29%) were discordant for the two conditions: n=165/410 (40%) had the MetS but were NGT, and n=245/410 (60%) had IGM but no MetS. Among IGM patients, n=168/757 (22%; of which 45 had no MetS) received a new diagnosis of diabetes based on OGTT criteria. Among all discordant patients, those with IGM and no MetS were more commonly males (p<0.001), and had older age (p<0.001) and lower body mass index (p<0.05).

CONCLUSIONS

Among patients with hypertension, the estimate of the prevalence of diabetes and prediabetes, hence of the global cardiovascular risk, can be seriously flawed unless an OGTT is performed. Our results support a wider use of the OGTT in the management of hypertension.

Association between low blood glucose increase during glucose tolerance tests in pregnancy and impaired fetal growth

OBJECTIVE

To evaluate how different levels of increase in maternal blood glucose from a fasting state to 2 h after an oral glucose challenge in late pregnancy are associated with fetal growth, with special emphasis on those with a low increase.

DESIGN

Prospective cohort study.

SUBJECTS

We followed 855 women, of whom 70% had an increased risk for carrying lighter babies.

STUDY DESIGN AND METHODS

Ultrasound was used to estimate fetal growth in gestational weeks 25, 33 and 37. In week 37 the women had a 75-g oral glucose tolerance test, and fasting and 2-h capillary glucose values were recorded with the difference between these two called delta (∆) glucose. Three groups were constructed from the ∆ glucose distribution: Low below the 10th centile; Medium between the 10th and 90th centiles; and High above the 90th centile. Missing data were imputed. Linear and Poisson regression models were applied.

OUTCOME MEASURES

Estimated fetal weight, percent deviation from expected fetal weight and anthropometric measures at birth.

RESULTS

The Low group carried the lightest fetuses and the High group the heaviest. The fetal growth in the Low group deviated increasingly more in a negative direction from week 25 to 37 than in the other groups.

CONCLUSION

In a high-risk population, a positive relation between ∆ glucose and fetal growth was found. The Low group demonstrated impaired growth. More attention should be paid to pregnant women with an insufficient increase in glucose after a glucose challenge. Future studies should challenge our findings in high-risk and low-risk populations.

Synergistic postprandial blood glucose modulatory properties of Vernonia amygdalina (Del.), Gongronema latifolium (Benth.) and Occimum gratissimum (Linn.) aqueous decoctions

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional healers in Nigeria use a combination of decoctions from green leafy vegetables in their blood glucose (BG) lowering recipes. Three plants Vernonia amygdalina (Del.) (VA), Gongronema latifolium (Benth.) (GL) and Occimum gratissimum (Linn.) (OG) are found consistently in such recipes. Whereas the anti-diabetic properties of extracts of these plants have been reported in animal models, little is known about the effects of their aqueous decoctions (singly or in combinations) on oral glucose tolerance (OGT) in humans.

MATERIALS AND METHODS

Twenty seven subjects were recruited and (on separate days) were given 150 mL of water, VA, GL and OG decoctions or blends of the decoctions to drink 45 min before a 2-h OGTT. Their OGTT curves were plotted and areas under the curves (AUCs) calculated.

RESULTS

The results show that each of the three decoctions neither altered the peak time of the OGTT nor significantly (P>0.05) reduced the BG concentrations (BGCs) at any time point on the test curves relative to the baseline. VA, OG and GL gave 0.4, 0.2 and 2.8% reductions in the AUCs, respectively, relative to the baseline. Blending GL and VA did not improve the results. However, a decoction containing the three vegetables in equal proportions significantly reduced the BGCs at 90 (96.8 ± 9.5 vs. 107.1 ± 10.2mg/dL; P=0.041) and 120 (92.8 ± 14.3 vs. 102.5 ± 12.1mg/dL; P=0.037) minutes relative to the baseline, and gave better reductions in the AUCs (4.1%).

CONCLUSION

The decoction containing the three vegetables was found to be superior in activity to any 1, or blends of only 2, of the 3 decoctions. This is a case of positive synergism, and justifies the use of these plants in ethnopharmacological BG lowering recipes.

PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy

Short stature, hyperextensibility of joints and/or inguinal hernia, ocular depression, Rieger anomaly, and teething delay (SHORT) syndrome is a developmental disorder with an unknown genetic cause and hallmarks that include insulin resistance and lack of subcutaneous fat. We ascertained two unrelated individuals with SHORT syndrome, hypothesized that the observed phenotype was most likely due to de novo mutations in the same gene, and performed whole-exome sequencing in the two probands and their unaffected parents. We then confirmed our initial observations in four other subjects with SHORT syndrome from three families, as well as 14 unrelated subjects presenting with syndromic insulin resistance and/or generalized lipoatrophy associated with dysmorphic features and growth retardation. Overall, we identified in nine affected individuals from eight families de novo or inherited PIK3R1 mutations, including a mutational hotspot (c.1945C>T [p.Arg649Trp]) present in four families. PIK3R1 encodes the p85α, p55α, and p50α regulatory subunits of class IA phosphatidylinositol 3 kinases (PI3Ks), which are known to play a key role in insulin signaling. Functional data from fibroblasts derived from individuals with PIK3R1 mutations showed severe insulin resistance for both proximal and distal PI3K-dependent signaling. Our findings extend the genetic causes of severe insulin-resistance syndromes and provide important information with respect to the function of PIK3R1 in normal development and its role in human diseases, including growth delay, Rieger anomaly and other ocular affections, insulin resistance, diabetes, paucity of fat, and ovarian cysts.

Polycystic ovary syndrome and obesity do not affect vascular parameters related to early atherosclerosis in young women without glucose metabolism disturbances, arterial hypertension and severe abnormalities of lipid profile

The aim of this study was to evaluate the influence of polycystic ovary syndrome (PCOS) and obesity on vascular parameters related to early atherosclerosis (VP-EA) [brachial flow-mediated dilation (FMD), carotid intima-media thickness (CIMT) and carotid arterial compliance (CAC)] in women with minor cardiovascular risk factors (CVRFs). Twenty-five young women with PCOS and 23 eumenorrheic women matched for body mass index (BMI) were studied. The women were subdivided according to BMI and PCOS status, and comparisons were done between PCOS and Control group, regardless of BMI, and between Obese and Lean group, regardless of the presence of PCOS. Insulin resistance was higher in PCOS-group than in control-group and in obese-group than in lean-group. The median of all VP-EA evaluated were similar between PCOS-group and Control-group [FMD: 6.6 versus 8.4% (p = NS); CIMT: 48.0 versus 47.0 mm.10-2 (p = NS); CAC: 6.2 versus 5.6N-1.m4.10-10 (p = NS)] and between obese-group and lean-group [FMD: 7.8 versus 6.6% (p = NS); CIMT: 48.0 versus 47.0 mm.10-2 (p = NS); CAC: 5.7 versus 6.3N-1.m4.10-10 (p = NS)]. These results suggest that PCOS and obesity do not affect VP-EA in women with minor CVRFs.

Japan Diabetes Outcome Intervention Trial-1 (J-DOIT1), a nationwide cluster randomized trial of type 2 diabetes prevention by telephone-delivered lifestyle support for high-risk subjects detected at health checkups: rationale, design, and recruitment

BACKGROUND

Lifestyle modifications are considered the most effective means of delaying or preventing the development of type 2 diabetes (T2DM). To contain the growing population of T2DM, it is critical to clarify effective and efficient settings for intervention and modalities for intervention delivery with a wide population reach.The Japan Diabetes Outcome Intervention Trial-1 (J-DOIT1) is a cluster randomized controlled trial to test whether goal-focused lifestyle coaching delivered by telephone can prevent the development of T2DM in high-risk individuals in a real-world setting. This paper describes the study design and recruitment of the study subjects.

METHODS

For the recruitment of study subjects and their follow-up annually over 3 years, we employed health checkups conducted annually at communities and worksites. Health care divisions recruited from communities and companies across Japan formed groups as a cluster randomization unit. Candidates for the study, aged 20-65 years with fasting plasma glucose (FPG) of 5.6-6.9 mmol/l, were recruited from each group using health checkups results in 2006. Goal-focused lifestyle support is delivered by healthcare providers via telephone over a one-year period. Study subjects will be followed-up for three years by annual health checkups. Primary outcome is the development of diabetes defined as FPG≥7.0 mmol/l on annual health checkup or based on self-report, which is confirmed by referring to medical cards.

RESULTS

Forty-three groups (clusters), formed from 17 health care divisions, were randomly assigned to an intervention arm (22 groups) or control arm (21 clusters) between March 2007 and February 2008. A total of 2840 participants, 1336 from the intervention and 1504 from the control arm, were recruited. Consent rate was about 20%, with no difference between the intervention and control arms. There were no differences in cluster size and characteristics of cluster between the groups. There were no differences in individual characteristics between the study arms.

CONCLUSION

We have launched J-DOIT1, a nation-wide trial to prevent the development of T2DM in high-risk individuals using telephone-delivered intervention. This trial is expected to contribute to evidence-based real-world preventive practices.

TRIAL REGISTRATION

UMIN000000662.

Adult glucose metabolism in extremely birthweight-discordant monozygotic twins

AIMS/HYPOTHESIS

Low birthweight (BW) is associated with increased risk of type 2 diabetes. We compared glucose metabolism in adult BW-discordant monozygotic (MZ) twins, thereby controlling for genetic factors and rearing environment.

METHODS

Among 77,885 twins in the Danish Twin Registry, 155 of the most BW-discordant MZ twin pairs (median BW difference 0.5 kg) were assessed using a 2 h oral glucose tolerance test with sampling of plasma (p-)glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1. HOMA for beta cell function (HOMA-β) and insulin resistance (HOMA-IR), and also insulin sensitivity index (BIGTT-SI) and acute insulin response (BIGTT-AIR), were calculated. Subgroup analyses were performed in those with: (1) double verification of BW difference; (2) difference in BW >0.5 kg; and (3) no overt metabolic disease (type 2 diabetes, hyperlipidaemia or thyroid disease).

RESULTS

No intra-pair differences in p-glucose, insulin, C-peptide, incretin hormones, HOMA-β, HOMA-IR or BIGTT-SI were identified. p-Glucose at 120 min was higher in the twins with the highest BW without metabolic disease, and BIGTT-AIR was higher in those with the highest BW although not in pairs with a BW difference of >0.5 kg.

CONCLUSIONS/INTERPRETATION

BW-discordant MZ twins provide no evidence for a detrimental effect of low BW on glucose metabolism in adulthood once genetic factors and rearing environment are controlled for.

Possible effects of dietary polyphenols on sugar absorption and digestion

Excessive post-prandial glucose excursions are a risk factor for developing diabetes, associated with impaired glucose tolerance. One way to limit the excursion is to inhibit the activity of digestive enzymes for glucose production and of the transporters responsible for glucose absorption. Flavonols, theaflavins, gallate esters, 5-caffeoylqunic acid and proanthocyanidins inhibit α-amylase activity. Anthocyanidins and catechin oxidation products, such as theaflavins and theasinsensins, inhibit maltase; sucrase is less strongly inhibited but anthocyanidins seem somewhat effective. Lactase is inhibited by green tea catechins. Once produced in the gut by digestion, glucose is absorbed by SGLT1 and GLUT2 transporters, inhibited by flavonols and flavonol glycosides, phlorizin and green tea catechins. These in vitro data are supported by oral glucose tolerance tests on animals, and by a limited number of human intervention studies on polyphenol-rich foods. Acarbose is a drug whose mechanism of action is only through inhibition of α-amylases and α-glucosidases, and in intervention studies gives a 6% reduction in diabetes risk over 3 years. A lifetime intake of dietary polyphenols, assuming the same mechanism, has therefore a comparable potential to reduce diabetes risk, but more in vivo studies are required to fully test the effect of modulating post-prandial blood glucose in humans.

Impact of percent body fat on oral glucose tolerance testing: a cross-sectional study in 1512 obese children

BACKGROUND

Although an association between insulin resistance (IR) and body adiposity has been reported in obese children, this relationship has not been studied as thoroughly as in adults.

AIM

We evaluated the association between oral glucose tolerance testing (OGTT) and percent body fat (PBF) in a sample of 1512 obese children followed at a Pediatric Obesity Clinic.

SUBJECTS AND METHODS

Six hundred and twenty-eight male and 884 female obese children aged 6 to 18 yr were consecutively enrolled into the study. OGTT was performed with administration of 1.75 g of glucose per kg of body weight (up to 75 g). PBF was estimated through bioelectrical impedance analysis (BIA) using a population- specific formula recently published by our group. Multivariable median regression was used to evaluate the association between 4 outcomes [glucose area under the curve (AUC), insulin AUC, insulin sensitivity index (ISI), and insulinogenic index (IGI)] and gender, age or pubertal status and PBF.

RESULTS

Median PBF was 52% (range 26 to 70%). After correction for age and gender, a 10% increase of PBF was associated with a decrease of -0.50 [95% confidence interval (CI): -0.65 to -0.35] units of ISI and an increase of 0.15 units of IGI (95%CI 0.07 to 0.24).

CONCLUSIONS

In obese children, PBF is inversely associated with IR and directly associated to β-cell response as detected by OGTT.

Continuous enteral administration can overcome the limited capacity to absorb glucose in rats with methotrexate-induced gastrointestinal mucositis

BACKGROUND

Patients with chemotherapy-induced gastrointestinal mucositis often suffer from weight loss. It is not well known how to enterally feed mucositis patients, potentially experiencing malabsorption. Recently, we showed in a rat model of methotrexate (MTX)-induced mucositis that intestinal absorption of glucose in trace amounts is still intact. We now determined the quantitative capacity to absorb glucose in rats with mucositis, relative to controls.

METHODS

We administered a physiologically relevant amount of [1-(13)C]glucose-enriched glucose (meal size) as a bolus by oral gavage (2 g/kg once) or continuously by intraduodenal infusion (±1.9 g/(kg·h) for 5 h) to rats with MTX-induced mucositis and controls. Blood [1-(13)C]glucose concentrations were determined during the experimental period. To calculate the quantitative absorptive capacity, Steele's one-compartment model, including simultaneous intravenous infusion of [6,6-(2)H(2)]glucose, was used. After the experiment, jejunal histology and plasma citrulline concentrations were assessed.

RESULTS

MTX-induced mucositis was confirmed by a reduction in villus length and plasma citrulline (both -57%, relative to controls, P < 0.01). When glucose was administered as a bolus, MTX-treated rats only absorbed 15% of administered glucose, compared with 85% in controls (medians, P < 0.01). Upon continuous intraduodenal glucose infusion, the median absorptive capacity for glucose in MTX-treated rats did not differ from controls (80 versus 93% of administered glucose respectively, P = 0.06). However, glucose absorption differed substantially between individual MTX-treated rats (range, 21-95%), which correlated poorly with villus length (rho = 0.54, P = 0.030) and plasma citrulline (rho = 0.56, P = 0.024).

CONCLUSION

Continuous enteral administration can almost completely overcome the reduced absorptive capacity for glucose in rats with mucositis.

VO(dmpp)2 normalizes pre-diabetic parameters as assessed by in vivo magnetic resonance imaging and spectroscopy

Type 2 diabetes mellitus has been associated with obesity, metabolic syndrome, cardiovascular diseases and cancer. Attempts have been made for early diagnosis and finding effective drugs to prevent severe consequences and ameliorate the symptoms of this disorder. In this work, the pharmacological properties of VO(dmpp)(2), [bis(1,2-dimethyl-3-hydroxy-4-pyridinonato)oxovanadium(IV)], were in vivo evaluated. For 4 weeks fatty Zucker rats were subjected to a daily dose of VO(dmpp)(2) (44 μmol/kg) and their metabolic profile was followed by assessing different biological parameters at established time points: body weight, subcutaneous fat width and hepatic triglyceride content determined by magnetic resonance imaging and spectroscopy, respectively. A glucose tolerance test was performed at the end of the experiment. After treatment, treated obese rats presented a weight significantly lower than the non-treated obese animals (359.0±11.1 vs. 433.5±6.2g, P<0.05), a thinner subcutaneous fat width, and a statistically significant decrease in hepatic triglyceride content (5.41±0.59 vs. 21.03±1.40%, P<0.0005). Additionally, the glucose intolerant profile of fatty Zucker rats was completely reversed in treated animals (102.3±2.1 vs. 172.4±1.3 mg/100 mL; P<0.0005). These results reinforce the therapeutic action of VO(dmpp)(2) which shows particular effects on lipid metabolism.

Molecular validation of the acute phencyclidine rat model for schizophrenia: identification of translational changes in energy metabolism and neurotransmission

Administration of the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist phencyclidine (PCP) to rodents is widely used as preclinical model for schizophrenia. Most studies on this model employ methods investigating behavior and brain abnormalities. However, little is known about the corresponding peripheral effects. In this study, we analyzed changes in brain and serum molecular profiles, together with alterations in behavior after acute PCP treatment of rats. Furthermore, abnormalities in peripheral protein expression of first and recent onset antipsychotic free schizophrenia patients were assessed for comparison with the preclinical model. PCP treatment induced hyperlocomotion and stereotypic behavior, which have been related to positive symptoms of schizophrenia. Multiplex immunoassay profiling of serum revealed molecular abnormalities similar to those seen in first and recent onset, antipsychotic free schizophrenia patients. Also, increased insulin levels were detected after administration of a glucose tolerance test (GTT), consistent with previous studies showing changes in insulin signaling in patients with schizophrenia. Finally, schizophrenia-relevant alterations in brain molecules were found in the hippocampus and to a lesser extent in the frontal cortex using liquid-chromatography mass spectrometry and (1)H nuclear magnetic resonance spectroscopy. In conclusion, this study identified behavioral and molecular alterations in the acute PCP rat model, which are also observed in human schizophrenia. We propose that the corresponding changes in serum in both animals and patients may have utility as surrogate markers in this model to facilitate discovery and development of novel drugs for treatment of certain pathological features of schizophrenia.

Controversies on how diabetes is diagnosed

PURPOSE OF REVIEW

To evaluate the controversial aspects of diabetes diagnosis.

RECENT FINDINGS

Within the past 2 years, revised guidelines for the diagnosis of diabetes have been issued which endorse the use of the hemoglobin A1C as a diagnostic test, in addition to the previously recommended tests. Updated diagnostic criteria for gestational diabetes were also published in the same period. Recent publications on the current role of oral glucose tolerance tests and diagnosis of diabetes in the acutely ill are sparse. There are new recommendations regarding the use of genetic testing and antibody testing in establishing the cause of diabetes.

SUMMARY

The inclusion of A1C as a diagnostic test has many advantages including reproducibility of the test and convenience, but there are situations where the test is unreliable and it misses many individuals who would have been diagnosed by plasma glucose testing. The diagnostic threshold of 6.5% for the A1C remains controversial. There is still no consensus on the best approach to diagnose gestational diabetes. The role of the oral glucose tolerance test seems to be diminishing. Diagnosis of diabetes in acute illness is aided by A1C testing. Genetic and autoantibody testing in specific situations offer diagnostic and therapeutic utility.

Reproducibility of multiple repeated oral glucose tolerance tests

We assessed the oral glucose tolerance test's (OGTT) ability to produce consistent results for estimating insulin sensitivity over four consecutive days. Individual coefficients of variation for OGIS and Stumvoll-ISI were 7.8% and 14.4% with no statistically significant difference between days. Thereby, indicating repeated OGTT's are reliable for estimating insulin sensitivity.

Dietary fatty acids linking postprandial metabolic response and chronic diseases

Chronic diseases are by far one of the main causes of mortality in the world. One of the current global recommendations to counteract disability and premature death resulting from chronic diseases is to decrease the consumption of energy-dense high-fat diets, particularly those rich in saturated fatty acids (SFA). The most effective replacement for SFA in terms of risk factor outcomes for chronic disease are polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA). The biochemical basis for healthy benefits of such a dietary pattern has been widely evaluated under fasting conditions. However, the increasing amount of data available from multiple studies suggest that the postprandial state, i.e., "the period that comprises and follows a meal", plays an important, yet underappreciated, role in the genesis of numerous pathological conditions. In this review, the potential of MUFA, PUFA, and SFA to postprandially affect selected metabolic abnormalities related to chronic diseases is discussed.

ELOVL6 genetic variation is related to insulin sensitivity: a new candidate gene in energy metabolism

Background

The elongase of long chain fatty acids family 6 (ELOVL6) is an enzyme that specifically catalyzes the elongation of saturated and monounsaturated fatty acids with 12, 14 and 16 carbons. ELOVL6 is expressed in lipogenic tissues and it is regulated by sterol regulatory element binding protein 1 (SREBP-1).

Objective

We investigated whether ELOVL6 genetic variation is associated with insulin sensitivity in a population from southern Spain.

Design

We undertook a prospective, population-based study collecting phenotypic, metabolic, nutritional and genetic information. Measurements were made of weight and height and the body mass index (BMI) was calculated. Insulin resistance was measured by homeostasis model assessment. The type of dietary fat was assessed from samples of cooking oil taken from the participants' kitchens and analyzed by gas chromatography. Five SNPs of the ELOVL6 gene were analyzed by SNPlex.

Results

Carriers of the minor alleles of the SNPs rs9997926 and rs6824447 had a lower risk of having high HOMA_IR, whereas carriers of the minor allele rs17041272 had a higher risk of being insulin resistant. An interaction was detected between the rs6824447 polymorphism and the intake of oil in relation with insulin resistance, such that carriers of this minor allele who consumed sunflower oil had lower HOMA_IR than those who did not have this allele (P = 0.001).

Conclusions

Genetic variations in the ELOVL6 gene were associated with insulin sensitivity in this population-based study.