Neprilysin is a ubiquitous peptidase that can modulate glucose homeostasis by cleaving insulinotropic peptides. While global deletion of neprilysin protects mice against high fat diet (HFD)-induced insulin secretory dysfunction, strategies to ablate neprilysin in a tissue-specific manner are favored to limit off-target effects. Since insulinotropic peptides are produced in the gut, we sought to determine whether gut-specific neprilysin deletion confers beneficial effects on insulin secretion similar to that of global neprilysin deletion in mice fed HFD. Mice with conditional deletion of neprilysin in enterocytes (NEPGut-/-) were generated by crossing Vil-Cre and floxed neprilysin (NEPfl/fl) mice. Neprilysin activity was almost abolished throughout the gut in NEPGut-/- mice, and was similar in plasma, pancreas and kidney in NEPGut-/- vs control mice. An oral glucose tolerance test was performed at baseline and following 14 weeks of HFD feeding, during which glucose tolerance and glucose-stimulated insulin secretion (GSIS) were assessed. Despite similar body weight gain at 14 weeks, NEPGut-/- displayed lower fasting plasma glucose levels, improved glucose tolerance and increased GSIS compared to control mice. In conclusion, gut-specific neprilysin deletion recapitulates the enhanced GSIS seen with global neprilysin deletion in high-fat-fed mice. Thus, strategies to inhibit neprilysin specifically in the gut may protect against fat-induced glucose intolerance and beta-cell dysfunction.

Undaria pinnatifida (UP) contains multiple bioactive substances, such as polyphenols, polysaccharides, and amino acids, which are associated with various biological properties. This study aimed to evaluate the antihyperglycemic effects of three extracts obtained from UP. UP was extracted under three different conditions: a low-temperature water extract at 50 °C (UPLW), a high-temperature water extract at 90 °C (UPHW), and a 70 % ethanol extract (UPE). Nontargeted chemical profiling using high-performance liquid chromatography-triple/time-of-flight mass spectrometry (HPLC-Triple TOF-MS/MS) was conducted on the three UP extracts. Subsequently, α-glucosidase inhibitory (AGI) activity, glucose uptake, and the mRNA expression of sodium/glucose cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2) were evaluated in Caco-2 cell monolayers. Furthermore, an oral carbohydrate tolerance test was performed on C57BL/6 mice. The mice were orally administered UP at 300 mg/kg body weight (B.W.), and the blood glucose level and area under the curve (AUC) were measured. Compared with glucose, UPLW, UPHW and UPE significantly inhibited both glucose uptake and the mRNA expression of SGLT1 and GLUT2 in Caco-2 cell monolayers. After glucose, maltose, and sucrose loading, the blood glucose levels and AUC of the UPLW group were significantly lower than those of the control group. These findings suggest that UPLW has antihyperglycemic effects by regulating glucose uptake through glucose transporters and can be expected to alleviate postprandial hyperglycemia. Therefore, UPLW may have potential as a functional food ingredient for alleviating postprandial hyperglycemia.

BACKGROUND: Adult people living with Cystic Fibrosis (CF) undergo annual screening for CF-related diabetes. These tests represent a burden and can lead to undesirable effects resulting in low adherence. The objectives of this study were to 1) compare gold-standard in-hospital oral glucose tolerance testing (OGTT) with at-home options, and 2) evaluate acceptability of at-home options.
METHODS: A total of 34 adults living with CF undertook 3 types of OGTTs in standardized conditions within two weeks: 1) in a hospital using a 75 g glucose beverage, 2) at home with the same glucose beverage, and 3) at home using a standardized quantity of candy. Glucose levels were measured prior to the OGTT, after 1 and 2 hours. Concordance of glucose measurement, side effects and general appreciation were assessed across the three options.
RESULTS: Mean blood glucose was comparable among the three tests. Glucose tolerance categorization (normal, impaired glucose tolerance, or diabetes) was concordant with the hospital reference test in 59 % of participants for the glucose beverage and 75 % for the candies. Side effects were mild with all types of OGTTs, and 94 % of participants preferred the home options. Among the at-home OGTTs, the glucose beverage was preferred to the candy option.
CONCLUSIONS: Home-based OGTT could be an alternative to gold standard hospital-based OGTT testing, improving adherence to annual testing and reducing costs. However, the discrepancy between various OGTT testing methods could lead to diagnosis dilemma. This approach should be tested on a larger sample size.

UNASSIGNED: Although diabetes is one of the most common side effects of clozapine, a medication for the treatment of schizophrenia, to the best of our knowledge no study exists on clozapine-induced glucose intolerance or hypoglycemia in patients with schizophrenia.
UNASSIGNED: We report a case of schizophrenia with repeated reactive hypoglycemia due to abnormal glucose tolerance during clozapine treatment. During clozapine administration in patients with schizophrenia, it is necessary to monitor physical and psychiatric symptoms due to reactive hypoglycemia and hyperglycemia. If abnormal glucose tolerance is a concern, it should be promptly detected using blood or oral glucose tolerance tests.
UNASSIGNED: Early intervention for impaired glucose tolerance may prevent clozapine discontinuation due to diabetes or hyperglycemia.

UNASSIGNED: Insulinoma is one of the causes of recurrent hypoglycemia, one of the chief complaints for emergency department admission. The gold standard in diagnosing insulinoma is a 72-hour fasting test which is inconvenient and inefficient as it requires hospitalization. Research has found that measurement of insulin and C-peptide during OGTT may help diagnose insulinoma. We aimed to assess the diagnostic value of OGTT in diagnosing insulinoma.
UNASSIGNED: The literature search was conducted on 19 August 2022 using several databases (MEDLINE, Scopus, Embase, and ScienceDirect). All studies that measured OGTT as diagnostic tools in diagnosing insulinoma and 72-hour fasting test as reference standard were included. The quality assessment of the selected studies was based on the Centre of Evidence-Based Medicine University of Oxford and the Quality Assessment of Diagnostic Accuracy-2 tool (QUADAS-2). Analysis of the included studies was performed qualitatively. This study was registered on PROSPERO (CRD42022360205).
UNASSIGNED: A total of two case-control studies (106 patients) were included, which were at risk of bias and low concern of applicability. Both studies demonstrated that the combination of insulin and C-peptide levels measured during OGTT had high specificity, sensitivity, positive predictive value, and negative predictive value in diagnosing insulinoma compared to the reference standard. A logistic regression model of 8.305 - (0.441 × insulin 2-h/0-h) - (1.679 × C-peptide 1-h/0-h) >0.351 has the highest diagnostic value in one study (AUC 0.97, Sensitivity 86.5%, Specificity 95.2%, PPV 94.1, NPV 88.9).
UNASSIGNED: The measurement of 0-h and 2-h insulin and C-peptide levels during 2-h OGTT was found in two small case-control studies with a total of 106 patients to have good sensitivity and specificity. However, due to these limitations, future research is still needed to validate the potential use of OGTT for the diagnosis of insulinoma.

OBJECTIVE: To assess the association between sociodemographic and clinical factors with body mass index (BMI) in a population at risk of type 2 diabetes (T2D) in Bogotá and Barranquilla, Colombia.
METHODS: This cross-sectional study used data from the PREDICOL Study. Participants with a FINDRISC ≥ 12 who underwent an Oral Glucose Tolerance Test (OGTT) were included in the study (n=1166). The final analytical sample size was 1101 participants. Those with missing data were excluded from the analysis (n=65). The main outcome was body mass index (BMI), which was categorized as normal, overweight, and obese. We utilized unadjusted and adjusted ordinal logistic regression analysis to calculate odds ratios (OR) and 95 % confidence intervals (CI).
RESULTS: The prevalence of overweight and obesity was 41 % (n=449) and 47 % (n=517), respectively. Participants with a 2-hour glucose ≥139 mg/dl had 1.71 times higher odds of being overweight or obese (regarding normal weight) than participants with normal 2-hour glucose values. In addition, being a woman, waist circumference altered, and blood pressure >120/80 mmHg were statistically significantly associated with a higher BMI.
CONCLUSIONS: Strategies to control glycemia, blood pressure, and central adiposity are needed in people at risk of T2D. Future studies should be considered with a territorial and gender focus, considering behavioral, and sociocultural patterns.

Our previous study revealed over 50% of recipients with pre-transplant impaired glucose tolerance (IGT) improved to normal glucose tolerance after kidney transplantation. However, the mechanism is unclear. We aimed to investigate whether the changes in glucose tolerance are associated with beta-cell function and insulin resistance in Japanese kidney transplant recipients with pre-transplant IGT. Of the 265 recipients who received kidney transplantation, 54 with pre-transplant IGT were included. We divided the recipients into improvement and non-improvement groups according to the change in the area under the curve for glucose obtained from the oral glucose tolerance test (OGTT). Beta-cell function was estimated by the insulin secretion sensitivity index-2 (ISSI-2) and the disposition index (DI). Insulin resistance was estimated by the Matsuda index (MI) and the homeostasis model assessment of insulin resistance (HOMA-IR). ISSI-2, DI increased significantly after transplantation in the improved group (P<0.01, P<0.05, respectively), but not in the non-improved group. ΔISSI-2 and ΔDI were significantly and positively associated with pre-transplant 60-minute OGTT plasma glucose levels (both P<0.01). There were no differences in MI or HOMA-IR between these two groups after transplantation. In recipients not on pre-transplant dialysis, a significant negative association was found between Δblood urea nitrogen (BUN) and ΔDI (correlation coefficient: -0.48, P<0.05). In pre-transplant IGT recipients, improvements in glucose tolerance after kidney transplantation were linked to improvements in beta-cell function. The higher the 60-minute OGTT plasma glucose level, the greater the improvement in post-transplant beta-cell function. Improvements in BUN after transplantation were associated with improvements in beta-cell function.

UNASSIGNED: This study aimed to investigate whether there is a difference in lipid levels between prediabetic individuals with one-hour post-Oral Glucose Tolerance Test (OGTT) plasma glucose (PG) values > 155 mg/dl and those with one-hour PG values ≤ 155 mg/dl.
UNASSIGNED: This retrospective cross sectional study was initiated on August 2020 and concluded on June 2021, and conducted with 229 prediabetic patients who presented to the Diabetes Clinic of the Research Hospital. A correlation analysis was performed to investigate the relationship between OGTT values and serum lipid levels. Additionally, the patients were divided into two groups based on the one-hour post-OGTT PG value of 155 mg/dl, and the presence of any difference in serum lipid levels between the two groups was examined using the Mann-Whitney U test. The SPSS 20 software was used for statistical analysis, and a statistical significance level of P < 0.05 was considered.
UNASSIGNED: Out of the 229 prediabetic patients included in the study, 172 were female. The number of patients with one-hour post-OGTT PG ≤ 155 mg/dl was 86, while those with values > 155 mg/dl were 143. A statistically significant difference was found between the group with one-hour post-OGTT PG > 155 mg/dl and the group with ≤ 155 mg/dl in terms of high-density lipoprotein (HDL-C) and triglyceride (TG) levels. There was a statistically significant negative correlation between one-hour PG and HDL-C.
UNASSIGNED: The evaluation of HDL-C and TG levels is important in prediabetic patients with a one-hour OGTT PG level greater than 155 mg/dL.

This study investigated the dynamic responses to an acute glucose challenge following chronic almond versus cracker consumption for 8 weeks (clinicaltrials.gov ID: NCT03084003). Seventy-three young adults (age: 18-19 years, BMI: 18-41 kg/m2) participated in an 8-week randomized, controlled, parallel-arm intervention and were randomly assigned to consume either almonds (2 oz/d, n=38) or an isocaloric control snack of graham crackers (325 kcal/d, n=35) daily for 8 weeks. Twenty participants from each group underwent a 2-hour oral glucose tolerance test (oGTT) at the end of the 8-week intervention. Metabolite abundances in the oGTT serum samples were quantified using untargeted metabolomics, and targeted analyses for free PUFAs, total fatty acids, oxylipins, and endocannabinoids. Multivariate, univariate, and chemical enrichment analyses were conducted to identify significant metabolic shifts. Findings exhibit a biphasic lipid response distinguished by higher levels of unsaturated triglycerides in the earlier periods of the oGTT followed by lower levels in the latter period in the almond versus cracker group (p-value<0.05, chemical enrichment analyses). Almond (vs. cracker) consumption was also associated with higher AUC120 min of aminomalonate, and oxylipins (p-value<0.05), but lower AUC120 min of L-cystine, N-acetylmannosamine, and isoheptadecanoic acid (p-value<0.05). Additionally, the Matsuda Index in the almond group correlated with AUC120 min of CE 22:6 (r=-0.46; p-value<0.05) and 12,13 DiHOME (r=0.45; p-value<0.05). Almond consumption for 8 weeks leads to dynamic, differential shifts in response to an acute glucose challenge, marked by alterations in lipid and amino acid mediators involved in metabolic and physiological pathways.

OBJECTIVE: Gestational diabetes mellitus (GDM) is a heterogeneous condition. Given such variability among patients, the ability to recognise distinct GDM subgroups using routine clinical variables may guide more personalised treatments. Our main aim was to identify distinct GDM subtypes through cluster analysis using routine clinical variables, and analyse treatment needs and pregnancy outcomes across these subgroups.
METHODS: In this cohort study, we analysed datasets from a total of 2682 women with GDM treated at two central European hospitals (1865 participants from Charité University Hospital in Berlin and 817 participants from the Medical University of Vienna), collected between 2015 and 2022. We evaluated various clustering models, including k-means, k-medoids and agglomerative hierarchical clustering. Internal validation techniques were used to guide best model selection, while external validation on independent test sets was used to assess model generalisability. Clinical outcomes such as specific treatment needs and maternal and fetal complications were analysed across the identified clusters.
RESULTS: Our optimal model identified three clusters from routinely available variables, i.e. maternal age, pre-pregnancy BMI (BMIPG) and glucose levels at fasting and 60 and 120 min after the diagnostic OGTT (OGTT0, OGTT60 and OGTT120, respectively). Cluster 1 was characterised by the highest OGTT values and obesity prevalence. Cluster 2 displayed intermediate BMIPG and elevated OGTT0, while cluster 3 consisted mainly of participants with normal BMIPG and high values for OGTT60 and OGTT120. Treatment modalities and clinical outcomes varied among clusters. In particular, cluster 1 participants showed a much higher need for glucose-lowering medications (39.6% of participants, compared with 12.9% and 10.0% in clusters 2 and 3, respectively, p<0.0001). Cluster 1 participants were also at higher risk of delivering large-for-gestational-age infants. Differences in the type of insulin-based treatment between cluster 2 and cluster 3 were observed in the external validation cohort.
CONCLUSIONS: Our findings confirm the heterogeneity of GDM. The identification of subgroups (clusters) has the potential to help clinicians define more tailored treatment approaches for improved maternal and neonatal outcomes.