Tipepidine activates AMPK and improves adipose tissue fibrosis and glucose intolerance in high-fat diet-induced obese mice

Tipepidine (3-[di-2-thienylmethylene]-1-methylpiperidine) (TP) is a non-narcotic antitussive used in Japan. Recently, the potential application of TP in the treatment of neuropsychiatric disorders, such as depression and attention deficit hyperactivity disorder, has been suggested; however, its functions in energy metabolism are unknown. Here, we demonstrate that TP exhibits a metabolism-improving action. The administration of TP reduced high-fat diet-induced body weight gain in mice and lipid accumulation in the liver and increased the weight of epididymal white adipose tissue (eWAT) in diet-induced obese (DIO) mice. Furthermore, TP inhibited obesity-induced fibrosis in the eWAT. We also found that TP induced AMP-activated protein kinase (AMPK) activation in the eWAT of DIO mice and 3T3-L1 cells. TP-induced AMPK activation was abrogated by the transfection of liver kinase B1 siRNA in 3T3-L1 cells. The metabolic effects of TP were almost equivalent to those of metformin, an AMPK activator that is used as a first-line antidiabetic drug. In summary, TP is a potent AMPK activator, suggesting its novel role as an antidiabetic drug owing to its antifibrotic effect on adipose tissues.

High Incidence of Diabetes Mellitus After Distal Pancreatectomy and Its Predictors: A Long-term Follow-up Study

CONTEXT

Glucose tolerance worsens after distal pancreatectomy (DP); however, the long-term incidence and factors affecting interindividual variation in this worsening are unclear.

OBJECTIVE

To investigate the changes in diabetes-related traits before and after DP and to clarify the incidence of diabetes and its predictors.

METHODS

Among 493 registered patients, 117 underwent DP. Among these, 56 patients without diabetes before surgery were included in the study. Glucose and endocrine function were prospectively assessed using a 75-g oral glucose tolerance test preoperatively, 1 month after DP, and every 6 months thereafter for up to 36 months. Pancreatic volumetry was performed using multidetector row computed tomography before and after surgery.

RESULTS

Insulin secretion decreased and blood glucose levels worsened after DP. Residual pancreatic volume was significantly associated with the reserve capacity of insulin secretion but not with blood glucose levels or the development of diabetes. Among 56 patients, 33 developed diabetes mellitus. The cumulative incidence of diabetes at 36 months after DP was 74.1%. Multivariate Cox regression analysis showed that impaired glucose tolerance as a preoperative factor as well as a decreased insulinogenic index and impaired glucose tolerance at 1 month postoperatively were identified as risk factors for diabetes following DP.

CONCLUSION

Impaired glucose tolerance and reduced early-phase insulin response to glucose are involved in the development of new-onset diabetes after DP; the latter is an additional factor in the development of diabetes and becomes apparent when pancreatic beta cell mass is reduced after DP.

Studies in children with obesity in two European treatment centres show a high prevalence of impaired glucose metabolism in the Swedish cohort

AIM

To investigate the prevalence and possible risk factors for the development of impaired glucose metabolism in children and adolescents with obesity.

METHODS

This was a cross-sectional retrospective cohort study, including 634 patients with obesity and 98 normal weight controls aged 4-18 years from the Beta-cell function in Juvenile Diabetes and Obesity (Beta-JUDO) cohort, a dual-centre study at Uppsala University Hospital (Sweden) and Paracelsus Medical University Hospital (Salzburg, Austria) conducted between 2012 and 2021. A longitudinal subgroup analysis, including 188 of these subjects was performed. Impaired glucose metabolism was diagnosed by oral glucose tolerance tests according to American Diabetes Association criteria.

RESULTS

The prevalence of impaired glucose metabolism was 72% in Uppsala patients, 24% in Salzburg patients, 30% in Uppsala controls and 13% in Salzburg controls. The prevalence was lower at the follow-up visits compared with baseline both in Uppsala and Salzburg patients. A family history of type 2 diabetes showed the strongest association with impaired glucose metabolism at the follow-up visits besides belonging to the Uppsala cohort.

CONCLUSION

The prevalence of impaired glucose metabolism was extraordinarily high in Swedish children and adolescents with obesity, but decreased during the follow-up period.

KLF4 down-regulation underlies placental angiogenesis impairment induced by maternal glucose intolerance in late pregnancy

Maternal glucose intolerance in late pregnancy can easily impair pregnancy outcomes and placental development. The impairment of placental angiogenesis is closely related to the occurrence of glucose intolerance during pregnancy, but the mechanism remains largely unknown. In this study, the pregnant mouse model of maternal high-fat diet and endothelial injury model of porcine vascular endothelial cells (PVECs) was used to investigate the effect of glucose intolerance on pregnancy outcomes and placental development. Feeding pregnant mice, a high-fat diet was shown to induce glucose intolerance in late pregnancy, and significantly increase the incidence of resorbed fetuses. Moreover, a decrease was observed in the proportion of blood sinusoids area and the expression level of CD31 in placenta, indicating that placental vascular development was impaired by high-fat diet. Considering that hyperglycemia is an important symptom of glucose intolerance, we exposed PVECs to high glucose (50 mM), which verified the negative effects of high glucose on endothelial function. Bioinformatics analysis further emphasized that high glucose exposure could significantly affect the angiogenesis-related functions of PVECs and predicted that Krüppel-like factor 4 (KLF4) may be a key mediator of these functional changes. The subsequent regulation of KLF4 expression confirmed that the inhibition of KLF4 expression was an important reason why high glucose impaired the endothelial function and angiogenesis of PVECs. These results indicate that high-fat diet can aggravate maternal glucose intolerance and damage pregnancy outcome and placental angiogenesis, and that regulating the expression of KLF4 may be a potential therapeutic strategy for maintaining normal placental angiogenesis.

Myosteatosis as a novel predictor of new-onset diabetes mellitus after kidney transplantation

OBJECTIVES

We evaluate the effect of myosteatosis on new-onset diabetes mellitus after kidney transplantation.

METHODS

Consecutive patients who had renal transplant between 2006 and 2021 were reviewed, and 219 patients were finally included. Psoas muscle index was used to evaluate sarcopenia and average total psoas density (calculated by computed tomography before surgery) for myosteatosis. We used Cox proportional regression analyses in investigation of whether skeletal muscle depletion before surgery inclusive of sarcopenia and myosteatosis is a new additional predictor of new-onset diabetes mellitus.

RESULTS

Median recipient age and body mass index were 45 years and 21.1 kg/m2 , respectively, and 123 patients (56%) were male. Preoperative impaired glucose tolerance was present in 58 patients (27%) and new-onset diabetes mellitus in 30 patients (14%), with median psoas muscle index of 6 cm2 /m2 and average total psoas density of 41 Hounsfield Unit. In multivariate analysis, significant risk factors were body mass index ≥25 kg/m2 (p < 0.01), impaired glucose tolerance (p < 0.01), and average total psoas density < 41.9 Hounsfield Unit (p = 0.03). New-onset diabetes mellitus had incidence rates of 3.7% without risk factors, 10% with a single risk factor, 33% with two, and 60% with three. Patients with new-onset diabetes mellitus were effectively stratified by the number of risk factors (p < 0.01).

CONCLUSIONS

Myosteatosis could be a new risk factor used to predict new-onset diabetes mellitus.

Apolipoprotein A-IV-Deficient Mice in 129/SvJ Background Are Susceptible to Obesity and Glucose Intolerance

Apolipoprotein A-IV (apoA-IV), synthesized by enterocytes, is potentially involved in regulating lipid absorption and metabolism, food intake, and glucose metabolism. In this study, we backcrossed apoA-IV knockout (apoA-IV-/-) mice onto the 129/SvJ background for eight generations. Compared to the wild-type (WT) mice, the 129/SvJ apoA-IV-/- mice gained more weight and exhibited delayed glucose clearance even on the chow diet. During a 16-week high-fat diet (20% by weight of fat) study, apoA-IV-/- mice were more obese than the WT mice, which was associated with their increased food intake as well as reduced energy expenditure and physical activity. In addition, apoA-IV-/- mice developed significant insulin resistance (indicated by HOMA-IR) with severe glucose intolerance even though their insulin levels were drastically higher than the WT mice. In conclusion, we have established a model of apoA-IV-/- mice onto the 129/SvJ background. Unlike in the C57BL/6J strain, apoA-IV-/- 129/SvJ mice become significantly more obese and insulin-resistant than WT mice. Our current investigations of apoA-IV in the 129/SvJ strain and our previous studies in the C57BL/6J strain underline the impact of genetic background on apoA-IV metabolic effects.

Minor Changes in Daily Rhythms Induced by a Skeleton Photoperiod Are Associated with Increased Adiposity and Glucose Intolerance

Eating during the rest phase is associated with metabolic syndrome, proposed to result from a conflict between food consumption and the energy-saving state imposed by the circadian system. However, in nocturnal rodents, eating during the rest phase (day-feeding, DF) also implies food intake during light exposure. To investigate whether light exposure contributes to DF-induced metabolic impairments, animals receive food during the subjective day without light. A skeleton photoperiod (SP) is used to entrain rats to a 12:12 cycle with two short light pulses framing the subjective day. DF-induced adiposity is prevented by SP, suggesting that the conflict between light and feeding stimulates fat accumulation. However, all animals under SP conditions develop glucose intolerance regardless of their feeding schedule. Moreover, animals under SP with ad libitum or night-feeding have increased adiposity. SP animals show a delayed onset of the daily rise in body temperature and energy expenditure and shorter duration of nighttime activity, which may contribute to the metabolic disturbances. These data emphasize that metabolic homeostasis can only be achieved when all daily cycling variables are synchronized. Even small shifts in the alignment of different metabolic rhythms, such as those induced by SP, may predispose individuals to metabolic disease.

Effect of (poly)phenol-rich 'Daux Belan' apple supplementation on diet-induced obesity and glucose intolerance in C57BL/6NCrl mice

Obesity is a state of metabolic dysfunction that can lead to dyslipidemia and impaired glucose homeostasis. Apple polyphenols have been shown to ameliorate dyslipidemia/metabolic dysfunction in humans. The influence of apple (poly)phenols on energy metabolism in high-fat (HF) diet-induced obese mice remains controversial. This study examined the effect of dietary supplementation of (poly)phenol-rich 'Daux Belan' apple (DB; 6.2 mg gallic acid equivalence (GAE)/mouse/day; 0.15% (poly)phenol) in the form of freeze-dried powder on glucose and lipid metabolism in male HF-fed C57BL/6NCrl mice, in comparison to low-(poly)phenol-containing 'Zestar' apple (Z; 0.4 mg GAE/mouse/day). Obesity, glucose intolerance, hypertriglyceridemia, and hepatic lipid vacuolation were induced by HF feeding while circulating cholesterol levels remained unchanged. DB apple supplementation did not protect against HF-induced body weight gain, hyperglycemia, hepatic triglyceride level elevation, and hepatic lipid vacuolation at the tested dosage. Future studies should be conducted with increased DB dosage and employ apple (poly)phenols supplemented in the form of extracts or sugar-free powder.

Susceptibility to Low Vitamin B6 Diet-induced Gestational Diabetes Is Modulated by Strain Differences in Mice

Gestational diabetes is a common pregnancy complication that adversely influences the health and survival of mother and child. Pancreatic islet serotonin signaling plays an important role in β-cell proliferation in pregnancy, and environmental and genetic factors that disrupt serotonin signaling are associated with gestational diabetes in mice. Our previous studies show that pregnant C57BL/6J mice fed a diet that is low in vitamin B6, a critical co-factor in serotonin synthesis, develop hyperglycemia and glucose intolerance, phenotypes that are consistent with gestational diabetes in humans. The current study shows that, unlike in the C57BL/6J mice, low vitamin B6 diet does not alter glucose tolerance and insulin secretion in pregnant DBA/2J mice. The hypothesis to be tested in the current study is that pregnant DBA/2J mice are protected against low vitamin B6-induced gestational diabetes due to their higher expression and enzymatic activities of tissue nonspecific alkaline phosphatase (ALPL) relative to C57BL/6J. ALPL is a rate-limiting enzyme that regulates vitamin B6 bioavailability. Interestingly, treating pregnant DBA/2J mice with 7.5 mg/kg/day of the ALPL inhibitor SBI-425 is associated with glucose intolerance in low vitamin B6-fed mice, implying that inhibition of ALPL activity is sufficient to modulate resilience to low vitamin B6-induced metabolic impairment.

Myricetin derivative-rich fraction from Syzygium malaccense prevents high-fat diet-induced obesity, glucose intolerance and oxidative stress in C57BL/6J mice

AIM

A high-fat diet (HFD) can lead to obesity and related metabolic disorders. This study evaluated the preventive efficacy of myricetin derivative-rich fraction (MD) from Syzygium malaccense leaf extract against HFD-induced obesity, hyperglycaemia, and oxidative stress in C57BL/6J mice.

METHODS

HFD-fed mice were administered MD (50 mg/kg, 100 mg/kg, and 150 mg/kg) or 2 mg/kg metformin (positive control) orally for 16 weeks. Normal diet and HFD-fed control groups received normal saline.

RESULTS

MD dose of 50 mg/kg was better than 100 mg/kg and 150 mg/kg in significantly reducing weight-gain, glucose intolerance, insulin resistance, lipid accumulation in liver and kidney, and improving the serum lipid profile. Lowered protein carbonyls and lipid hydroperoxides in urine and tissue homogenates and elevated reduced glutathione, ferric reducing antioxidant power (FRAP), and Trolox equivalent antioxidant capacity (TEAC) levels in tissue homogenates indicated amelioration of oxidative stress.

CONCLUSION

MD has therapeutic value in the prevention and management of obesity, hyperglycaemia, and oxidative stress.

Marginal association of fasting blood glucose with the risk of cystic fibrosis-related diabetes

OBJECTIVES

Cystic fibrosis-related diabetes (CFRD) may be diagnosed by fasting blood glucose ≥ 7.0 mmol/L and/or glucose ≥ 11.1 mmol/L following oral glucose tolerance test (OGTT). We compared the role of fasting and stimulated glucose for diagnosis of CFRD.

METHODS

We performed a cross-sectional review of the prevalence of fasting glycemic abnormalities and Kaplan-Meier survival analysis of risk of progression to CFRD according to baseline fasting glucose in the prospective Montreal Cystic Fibrosis Cohort.

RESULTS

Isolated fasting hyperglycemia was detected in only 8% of participants at study onset. Eighty percent of subjects had isolated post-challenge hyperglycemia on their first OGTT meeting criteria for CFRD. Kaplan Meier survival analysis demonstrated that impaired fasting glucose (IFG) alone is not a risk factor for CFRD. Subjects with combined IFG and impaired glucose tolerance at baseline (IGT) had the highest risk of progression to CFRD.

CONCLUSION

Post-prandial elevations in blood glucose are more common at diagnosis of CFRD. While IGT is a significant risk factor for CFRD, IFG alone is uncommon and does not increase the risk of CFRD. Patients with both IGT and IFG have the highest risk of CFRD.

Pancreatic β-cell hyper-O-GlcNAcylation leads to impaired glucose homeostasis in vivo

Protein O-GlcNAcylation is a nutrient and stress-sensitive protein post-translational modification (PTM). The addition of an O-GlcNAc molecule to proteins is catalyzed by O-GlcNAc transferase (OGT), whereas O-GlcNAcase (OGA) enzyme is responsible for removal of this PTM. Previous work showed that OGT is highly expressed in the pancreas, and we demonstrated that hypo-O-GlcNAcylation in β-cells cause severe diabetes in mice. These studies show a direct link between nutrient-sensitive OGT and β-cell health and function. In the current study, we hypothesized that hyper-O-GlcNAcylation may confer protection from β-cell failure in high-fat diet (HFD)-induced obesity. To test this hypothesis, we generated a mouse model with constitutive β-cell OGA ablation (βOGAKO) to specifically increase O-GlcNAcylation in β-cells. Under normal chow diet, young male and female βOGAKO mice exhibited normal glucose tolerance but developed glucose intolerance with aging, relative to littermate controls. No alteration in β-cell mass was observed between βOGAKO and littermate controls. Total insulin content was reduced despite an increase in pro-insulin to insulin ratio in βOGAKO islets. βOGAKO mice showed deficit in insulin secretion in vivo and in vitro. When young animals were subjected to HFD, both male and female βOGAKO mice displayed normal body weight gain and insulin tolerance but developed glucose intolerance that worsened with longer exposure to HFD. Comparable β-cell mass was found between βOGAKO and littermate controls. Taken together, these data demonstrate that the loss of OGA in β-cells reduces β-cell function, thereby perturbing glucose homeostasis. The findings reinforce the rheostat model of intracellular O-GlcNAcylation where too much (OGA loss) or too little (OGT loss) O-GlcNAcylation are both detrimental to the β-cell.

Plant-Based Dietary Patterns versus Meat Consumption and Prevalence of Impaired Glucose Intolerance and Diabetes Mellitus: A Cross-Sectional Study in Australian Women

This study aimed to compare the prevalence of impaired glucose tolerance (IGT) and diabetes mellitus (DM) among Australian women following plant-based diets (PBD) compared to regular meat eaters. A cross sectional analysis of the mid-aged cohort (1946−1951) of the Australian Longitudinal Study on Women’s Health was conducted on completers of Survey 7 in 2013 with complete FFQ data available (n = 9102). Dietary patterns were categorized as PBD (vegan, lacto-ovo vegetarian, pesco-vegetarian, semi-vegetarian) and regular meat eaters. Meat eaters were further categorized into high and low consumption and outcomes included self-reported prevalence of IGT and DM. Participants were identified as regular meat eaters (n = 8937) and PBD (n = 175). Prevalence of IGT was lower in PBD (0−1.2%) compared to regular meat eaters (9.1%). Consolidation of PBD to a single group (vegetarians) indicated a lower prevalence of DM in vegetarians compared to regular meat eaters (3.9% vs. 9.1%). Women consuming meat daily/multiple times per day had significantly higher odds of IGT (OR 1.5, 95%CI 1.1 to 2.1, p = 0.02). Individuals consuming processed meat daily/multiple times per day had significantly higher odds of DM compared to those consuming less than daily (Odds ratio (OR) 1.7, 95% confidence interval (CI) 1.3 to 2.3, p < 0.0001). After adjustment for covariates, statistical significance was lost largely due to the addition of BMI to the model. Prevalence of IGT and DM were lower in women following PBD and higher in high consumers of meat and processed meat. The relationship between meat consumption and IGT/diabetes status appears to be mediated, at least in part, by an increase in body mass index (BMI). Future studies are warranted to investigate the mechanisms and other lifestyle factors underpinning the association between high meat consumption and increased risk of IGT and DM.

Maternal intake of fructose or artificial sweetener during pregnancy and lactation has persistent effects on metabolic and reproductive health of dams post-weaning

As rates of obesity, diabetes, and related comorbidities have increased, the consumption of artificial sweeteners (ASs) as sugar substitutes has also risen in popularity as they are perceived as a healthier alternative to sugar sweetened products. However, there is conflicting evidence regarding the impact of AS intake on metabolic and reproductive health. Glucose intolerance during pregnancy due to intake of sugar sweetened foods can result in an increased risk for the development of type 2 diabetes post-pregnancy. However, limited information exists on the impact of AS intake during pregnancy and lactation on the mother's health in later life. We hypothesised both AS and fructose would impair metabolic health post-partum (PP) following maternal consumption during pregnancy and lactation. Female C57Bl/6 mice received a standard control diet ad libitum with either water (CD), fructose (Fr; 34.7 mm intake), or AS (AS;12.5 mm Acesulfame-K) throughout pregnancy and lactation. Post-weaning, AS and Fr dams were fed the CD diet for the remainder of the experiment. Oral glucose tolerance tests were undertaken 8 weeks PP and dams were humanely killed at 9 weeks PP, with adipose tissue and ovaries collected for analysis. Experimental diets did not influence maternal bodyweight. At 8 weeks PP, increased glucose intolerance was evident in both AS and Fr dams. Adipocyte size was significantly increased in both the AS and Fr groups PP. Further, in the ovary, AS increased expression of genes associated with follicular development and ovulation. Therefore, ASs may not represent beneficial substitutes to fructose during pregnancy, with the potential to increase the risk of T2DM in later life in mothers.

Association between lipid trajectories during pregnancy and risk of postpartum glucose intolerance after gestational diabetes mellitus: a cohort study

AIMS

To assess lipid trajectories throughout pregnancy in relation to early postpartum glucose intolerance in women with gestational diabetes mellitus (GDM).

METHODS

This prospective cohort study included 221 Chinese women with GDM who completed plasma lipid test in each trimester of pregnancy and oral glucose tolerance test at 6-9 weeks postdelivery between January 1, 2018 and January 8, 2020. Using the group-based trajectory modeling, total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-c), and high-density lipoprotein-cholesterol(HDL-c) were identified separately as three trajectories: low, moderate, and high trajectory. The associations between lipid trajectories and early postpartum glucose intolerance were all evaluated.

RESULTS

Seventy-three participants developed postpartum glucose intolerance. For patients in low, moderate and high trajectory, the incidence of postpartum glucose intolerance was 38.4%, 34.9%, and 17.9%, respectively. GDM women with lower LDL-c trajectories presented a higher risk of postpartum glucose intolerance. The adjusted odds ratio (95% CI) for glucose intolerance was 3.14 (1.17-8.39) in low LDL-c trajectory and 2.68 (1.05-6.85) in moderate trajectory when compared with the high one. However, TC trajectory was not associated with the risk of postpartum glucose intolerance, nor were TG trajectory and HDL-c trajectory. Moreover, a significant difference of insulin sensitivity was observed in participants with different LDL-c trajectories; participants in high LDL-c trajectory had the highest insulin sensitivity, whereas the women in low LDL-c trajectory had the lowest insulin sensitivity (P = 0.02).

CONCLUSIONS

The high trajectory of LDL-c during pregnancy may play a protective role on postpartum glucose intolerance in women with GDM. Further studies are warranted to explore the underlying mechanism. Trial registration The study was reviewed and approved by the Institutional Review Board of The First Affiliated Hospital of Sun Yat-sen University (reference number: [2014]No. 93). All participants provided written informed consent forms, and the ethics committee approved this consent procedure.

Dysglycemia screening with oral glucose tolerance test in adolescents with polycystic ovary syndrome and relationship with obesity

BACKGROUND

Adolescents with polycystic ovary syndrome (PCOS) are at increased risk of impaired glucose tolerance (IGT) and type 2 diabetes mellitus. The aim of this study is to evaluate dysglycemia and biochemical differences based on BMI status and assess the prognostic ability of elevated hemoglobin A1c (HbA1c) in predicting an abnormal 2 hour oral glucose tolerance test (OGTT).

METHODS

Retrospective cohort of female patients aged 11-18 years who underwent 75-g OGTT and were evaluated for PCOS at an urban tertiary care hospital between January 2002 to December 2017.

RESULTS

In 106 adolescents with PCOS who had OGTT results available, IGT was markedly pronounced in the ≥95th percentile BMI group (17 out of 72; 23.6%) compared with <95th percentile BMI group (4 out of 34; 11.7%). One patient with obesity met the criteria for type 2 diabetes. Patients with obesity had significantly higher homeostasis model assessment (HOMA-IR) and lower whole body insulin sensitivity index (WBISI) (p < 0.001) compared to patients without obesity. Free testosterone levels were also higher in patients with obesity (p< 0.03) and were significantly associated with HOMA-IR when controlling for body mass index (BMI). HbA1c did not demonstrate a strong ability to predict abnormal OGTT on receiver operating characteristic (ROC) curve analysis [Area under the curve (AUC) = 0.572, 95% CI: 0.428, 0.939]).

CONCLUSIONS

In a study to assess glucose abnormalities in adolescents with PCOS, IGT was found to be markedly increased in patients with obesity, with abnormal glucose metabolism identified in over one-fifth of the patients. HbA1c alone may be a poor test to assess IGT and we recommend that adolescents diagnosed with PCOS and obesity undergo formal oral glucose tolerance testing.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring.

As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders.

Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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Maternal heminic vs. non-heminic iron intake differentially and persistently imprints the offspring's fecal microbiota.

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Males from heme-fed dams exhibit increased gut lumen reactive aldehydes in absence of direct dietary exposure to heme iron.

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Some of the increased reactive aldehydes closely covariated with Orders belonging to Bacteroidales and Lachnospirales.

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Maternal exposure to dietary heme iron impairs gut barrier and glucose tolerance in male offspring.

Postpartum glucose intolerance following early gestational diabetes mellitus

BACKGROUND

Patients with gestational diabetes mellitus are at increased risk for type 2 diabetes mellitus or glucose intolerance postpartum compared with those without diabetes mellitus.

OBJECTIVE

We aimed to evaluate the association between early gestational diabetes mellitus and postpartum dysglycemia compared with gestational diabetes mellitus diagnosed by routine screening in a cohort of patients with obesity.

STUDY DESIGN

This was a secondary analysis of a randomized controlled trial of patients with obesity and singleton, nonanomalous gestations that compared early gestational diabetes mellitus screening at 14 to 20 weeks of gestation with routine screening at 24 to 28 weeks of gestation. Patients were included in this analysis if they were diagnosed with gestational diabetes mellitus at the primary study site. The primary outcome was postpartum dysglycemia, defined as any abnormality on 2-hour oral glucose tolerance test 6 weeks postpartum or clinical diagnosis based on hyperglycemia requiring pharmacotherapy after delivery with deferred glucose tolerance test. Maternal characteristics and outcomes were compared in bivariable analysis, and logistic regression estimated the association between early gestational diabetes mellitus and postpartum dysglycemia.

RESULTS

Of 119 patients included in this analysis, 30 were diagnosed by screening at <20 weeks of gestation and 89 at 24 to 28 weeks of gestation. Patients were overall similar in baseline characteristics. Patients with early gestational diabetes mellitus were more likely to have postpartum dysglycemia than those with gestational diabetes mellitus diagnosed with routine screening (36.7% vs 14.6%; odds ratio, 3.38; 95% confidence interval, 1.31-8.73). Most patients with early gestational diabetes mellitus who had postpartum dysglycemia were diagnosed clinically (n=7/11), whereas none of the patients with gestational diabetes mellitus established by routine testing were diagnosed with postpartum dysglycemia clinically. All (100%) patients with early gestational diabetes mellitus who completed a postpartum glucose tolerance test had dysglycemia compared with only 45% of patients with gestational diabetes mellitus diagnosed on routine screening. The proportion of patients who followed up for postpartum visits and the timing of follow-up were similar between groups. Postpartum glucose tolerance test completion was low but also similar between groups.

CONCLUSION

Although postpartum glucose tolerance test completion is low, patients with gestational diabetes mellitus before 20 weeks of gestation, seem to be at higher risk for postpartum dysglycemia than those with gestational diabetes mellitus diagnosed at routine screening in a cohort of patients with obesity. Larger studies are needed to confirm these findings, but postpartum follow-up and diabetes mellitus testing may be even more important to improve long-term health in patients with early gestational diabetes mellitus.

Isoform-Specific Role of GSK-3 in High Fat Diet Induced Obesity and Glucose Intolerance

Obesity-associated metabolic disorders are rising to pandemic proportions; hence, there is an urgent need to identify underlying molecular mechanisms. Glycogen synthase kinase-3 (GSK-3) signaling is highly implicated in metabolic diseases. Furthermore, GSK-3 expression and activity are increased in Type 2 diabetes patients. However, the isoform-specific role of GSK-3 in obesity and glucose intolerance is unclear. Pharmacological GSK-3 inhibitors are not isoform-specific, and tissue-specific genetic models are of limited value to predict the clinical outcome of systemic inhibiion. To overcome these limitations, we created novel mouse models of ROSA26CreERT2-driven, tamoxifen-inducible conditional deletion of GSK-3 that allowed us to delete the gene globally in an isoform-specific and temporal manner. Isoform-specific GSK-3 KOs and littermate controls were subjected to a 16-week high-fat diet (HFD) protocol. On an HFD, GSK-3α KO mice had a significantly lower body weight and modest improvement in glucose tolerance compared to their littermate controls. In contrast, GSK-3β-deletion-mediated improved glucose tolerance was evident much earlier in the timeline and extended up to 12 weeks post-HFD. However, this protective effect weakened after chronic HFD (16 weeks) when GSK-3β KO mice had a significantly higher body weight compared to controls. Importantly, GSK-3β KO mice on a control diet maintained significant improvement in glucose tolerance even after 16 weeks. In summary, our novel mouse models allowed us to delineate the isoform-specific role of GSK-3 in obesity and glucose tolerance. From a translational perspective, our findings underscore the importance of maintaining a healthy weight in patients receiving lithium therapy, which is thought to work by GSK-3 inhibition mechanisms.

Persistent high glucose induced EPB41L4A-AS1 inhibits glucose uptake via GCN5 mediating crotonylation and acetylation of histones and non-histones

BACKGROUND

Persistent hyperglycemia decreases the sensitivity of insulin-sensitive organs to insulin, owing to which cells fail to take up and utilize glucose, which exacerbates the progression of type 2 diabetes mellitus (T2DM). lncRNAs' abnormal expression is reported to be associated with the progression of diabetes and plays a significant role in glucose metabolism. Herein, we study the detailed mechanism underlying the functions of lncRNA EPB41L4A-AS1in T2DM.

METHODS

Data from GEO datasets were used to analyze the expression of EPB41L4A-AS1 between insulin resistance or type 2 diabetes patients and the healthy people. Gene expression was evaluated by qRT-PCR and western blotting. Glucose uptake was measured by Glucose Uptake Fluorometric Assay Kit. Glucose tolerance of mice was detected by Intraperitoneal glucose tolerance tests. Cell viability was assessed by CCK-8 assay. The interaction between EPB41L4A-AS1 and GCN5 was explored by RNA immunoprecipitation, RNA pull-down and RNA-FISH combined immunofluorescence. Oxygen consumption rate was tested by Seahorse XF Mito Stress Test.

RESULTS

EPB41L4A-AS1 was abnormally increased in the liver of patients with T2DM and upregulated in the muscle cells of patients with insulin resistance and in T2DM cell models. The upregulation was associated with increased TP53 expression and reduced glucose uptake. Mechanistically, through interaction with GCN5, EPB41L4A-AS1 regulated histone H3K27 crotonylation in the GLUT4 promoter region and nonhistone PGC1β acetylation, which inhibited GLUT4 transcription and suppressed glucose uptake by muscle cells. In contrast, EPB41L4A-AS1 binding to GCN5 enhanced H3K27 and H3K14 acetylation in the TXNIP promoter region, which activated transcription by promoting the recruitment of the transcriptional activator MLXIP. This enhanced GLUT4/2 endocytosis and further suppressed glucose uptake.

CONCLUSION

Our study first showed that the EPB41L4A-AS1/GCN5 complex repressed glucose uptake via targeting GLUT4/2 and TXNIP by regulating histone and nonhistone acetylation or crotonylation. Since a weaker glucose uptake ability is one of the major clinical features of T2DM, the inhibition of EPB41L4A-AS1 expression seems to be a potentially effective strategy for drug development in T2DM treatment.

Effect of nighttime light exposure on glucose metabolism in protein-restricted mice

Disruption of biological rhythms due to exposure to artificial light at night (ALAN) has emerged as a new risk factor for metabolic diseases. However, the effects of ALAN exposure on energy metabolism with concomitant misalignment in the circadian system caused by nutritional imbalance remain largely unexplored. Here, we evaluate whether a low-protein (LP) diet could enhance the effects induced by exposure to ALAN on the energy metabolism and consequently predispose to metabolic disorders. Male C57BL6/J mice were weaned on a normal protein (NP) or a LP diet and housed on 12 h light:12 h darkness (LD) cycle. After 6 weeks, mice maintained on their respective diets were subdivided into normal light/darkness cycle (NP/LD; LP/LD) or exposed to ALAN (NP/LL; LP/LL) for 8 weeks. We observed that exposure to ALAN concomitant to LP diet disrupts the behavioral rhythms, without shifting the timing of food intake. Furthermore, exposure to ALAN leads to increased body and fat pad weights, higher levels of fast and fed glycemia and glucose intolerance independent of the diet consumed. Importantly, the effects of ALAN on circadian regulation of insulin sensitivity were diet-dependent with LP/LL mice showing insulin resistance in an opposite time of day than NP/LL. At the molecular level, exposure to ALAN concurrent with LP diet increased the expression of phosphoenolpyruvate carboxykinase 1 in both periods analyzed and inverted the pattern of fibroblast growth factor 21 (Fgf21) expression in the liver. Our data suggest that dietary protein restriction modulates the effects induced by nighttime light exposure on glucose metabolism, which could be partially related with the dysregulation of hepatic Fgf21 expression.

Effects of Intermittent Hypoxia on Cytokine Expression Involved in Insulin Resistance

Sleep apnea syndrome (SAS) is a prevalent disorder characterized by recurrent apnea or hypoxia episodes leading to intermittent hypoxia (IH) and arousals during sleep. Currently, the relationship between SAS and metabolic diseases is being actively analyzed, and SAS is considered to be an independent risk factor for the development and progression of insulin resistance/type 2 diabetes (T2DM). Accumulating evidence suggests that the short cycles of decreased oxygen saturation and rapid reoxygenation, a typical feature of SAS, contribute to the development of glucose intolerance and insulin resistance. In addition to IH, several pathological conditions may also contribute to insulin resistance, including sympathetic nervous system hyperactivity, oxidative stress, vascular endothelial dysfunction, and the activation of inflammatory cytokines. However, the detailed mechanism by which IH induces insulin resistance in SAS patients has not been fully revealed. We have previously reported that IH stress may exacerbate insulin resistance/T2DM, especially in hepatocytes, adipocytes, and skeletal muscle cells, by causing abnormal cytokine expression/secretion from each cell. Adipose tissues, skeletal muscle, and the liver are the main endocrine organs producing hepatokines, adipokines, and myokines, respectively. In this review, we focus on the effect of IH on hepatokine, adipokine, and myokine expression.

CRISPR-enhanced human adipocyte browning as cell therapy for metabolic disease

Obesity and type 2 diabetes are associated with disturbances in insulin-regulated glucose and lipid fluxes and severe comorbidities including cardiovascular disease and steatohepatitis. Whole body metabolism is regulated by lipid-storing white adipocytes as well as "brown" and "brite/beige" adipocytes that express thermogenic uncoupling protein 1 (UCP1) and secrete factors favorable to metabolic health. Implantation of brown fat into obese mice improves glucose tolerance, but translation to humans has been stymied by low abundance of primary human beige adipocytes. Here we apply methods to greatly expand human adipocyte progenitors from small samples of human subcutaneous adipose tissue and then disrupt the thermogenic suppressor gene NRIP1 by CRISPR. Ribonucleoprotein consisting of Cas9 and sgRNA delivered ex vivo are fully degraded by the human cells following high efficiency NRIP1 depletion without detectable off-target editing. Implantation of such CRISPR-enhanced human or mouse brown-like adipocytes into high fat diet fed mice decreases adiposity and liver triglycerides while enhancing glucose tolerance compared to implantation with unmodified adipocytes. These findings advance a therapeutic strategy to improve metabolic homeostasis through CRISPR-based genetic enhancement of human adipocytes without exposing the recipient to immunogenic Cas9 or delivery vectors.

Hnf4g invalidation prevents diet-induced obesity via intestinal lipid malabsorption

Changes in dietary habits have occurred concomitantly with a rise of type 2 diabetes (T2D) and obesity. Intestine is the first organ facing nutrient ingestion and has to adapt its metabolism with these dietary changes. HNF-4γ, a transcription factor member of the nuclear receptor superfamily and mainly expressed in intestine, has been suggested to be involved in susceptibility to T2D. Our aim was to investigate the role of HNF-4γ in metabolic disorders and related mechanisms. Hnf4g-/- mice were fed high-fat/high-fructose (HF-HF) diet for 6 weeks to induce obesity and T2D. Glucose homeostasis, energy homeostasis in metabolic cages, body composition and stool energy composition, as well as gene expression analysis in the jejunum were analyzed. Despite an absence of decrease in calorie intake, of increase in locomotor activity or energy expenditure, Hnf4g-/- mice fed with HF-HF are protected against weight gain after 6 weeks of HF-HF diet. We showed that Hnf4g-/- mice fed HF-HF display an increase in fecal calorie loss, mainly due to intestinal lipid malabsorption. Gene expression of lipid transporters, Fatp4 and Scarb1 and of triglyceride-rich lipoprotein secretion proteins, Mttp and ApoB are decreased in gut epithelium of Hnf4g-/- mice fed HF-HF, showing the HNF-4γ role in intestine lipid absorption. Furthermore, plasma GLP-1 and jejunal GLP-1 content are increased in Hnf4g-/- mice fed HF-HF, which could contribute to the glucose intolerance protection. The loss of HNF-4γ leads to a protection against a diet-induced weight gain and to a deregulated glucose homeostasis, associated with lipid malabsorption.

Urinary C-peptide/creatinine ratio: A useful biomarker of insulin resistance and refined classification of type 2 diabetes mellitus

BACKGROUND

The urinary C-peptide/creatinine ratio (UCPCR) is low in patients with type 1 diabetes mellitus, but it has not been well characterized in patients with type 2 diabetes mellitus (T2DM). We aimed to measure the UCPCRs in patients with T2DM and explore the relationships among UCPCR, insulin resistance (IR), and chronic vascular complications of diabetes.

METHODS

A cross-sectional study was performed of 1299 Chinese hospitalized patients with T2DM. Binary logistic regression was used to evaluate the relationships between the chronic vascular complications of diabetes and UCPCR. K-means analysis was used to allocate participants to subgroups with five to six variables (age at diagnosis, body mass index [BMI], glycosylated hemoglobin, homoeostasis model assessment 2-estimated beta-cell function (HOMA2-B), and HOMA2-insulin resistance (HOMA2-IR), with or without UCPCR).

RESULTS

UCPCR positively correlated with HOMA2-IR (r = 0.448, P < .001). After adjustment for sex, age, duration of diabetes, and other cardiovascular risk factors, UCPCR was positively associated with diabetic kidney disease (DKD) (odds ratio [OR] = 1.198, 95% CI 1.019-1.408, P = .029) and coronary heart disease (CHD) (OR = 1.312, 95% CI 1.079-1.594, P = .006). When UCPCR was added, cluster analysis using the six variables identified five subgroups of T2DM, characterized by differing age at diagnosis, BMI, beta-cell function, IR, and prevalence of vascular complications.

CONCLUSIONS

UCPCR is positively associated with IR, DKD, and CHD and represents a promising biomarker that could refine the classification of T2DM.

Plasma glycated CD59 predicts postpartum glucose intolerance after gestational diabetes

AIM

To assess whether in women with gestational diabetes mellitus (GDM), postpartum plasma glycated CD59 (pGCD59) levels predict conversion to glucose intolerance diagnosed with an oral glucose tolerance test (OGTT).

METHODS

Blood levels of pGCD59 were measured in a case-control study of 105 women with GDM who underwent a 75 g OGTT 3 months postpartum. The 35 postpartum glucose intolerant cases were individually matched for age, BMI, ethnic origin, and parity with 70 women with GDM but normal postpartum OGTT (controls). The GDM cohort (105) was also matched with 105 normal glucose tolerant women during pregnancy. pGCD59 was measured by ELISA in standard peptide units (SPU).

RESULTS

Mean pGCD59 postpartum was significantly higher in cases than in controls (1.5 ± 0.6 SPU vs 1.0 ± 0.6 SPU, P < 0.001). The area under the receiving operating characteristic curve (AUC) in cases vs controls was 0.72 (95% CI: 0.62-0.83) for postpartum pGCD59 and 0.50 (95% CI: 0.36-0.61) for postpartum HbA1c. A 0.5-unit increase in postpartum pGCD59 was associated with an odds ratio (OR) of 3.3 (95% CI: 1.82-6.16, P < 0.001) for glucose intolerance postpartum. A pGCD59 cut-off postpartum of 0.9 SPU had a sensitivity of 85.7% (95% CI: 69.7-95.2%), specificity of 47.8% (95% CI: 35.6-60.2%), positive predictive value of 45.4% (95% CI: 33.1-58.2%), and negative predictive value of 86.8% (95% CI: 71.9-95.6%). pGCD59 in pregnancy was a poor predictor for glucose intolerance postpartum (AUC of 0.61 (95% CI: 0.50-0.72)).

CONCLUSION

pGCD59 might identify women at low risk for glucose intolerance postpartum and could help to avoid an OGTT.

Chronic high-fat feeding and prolonged fasting in liver-specific ANGPTL4 knockout mice

Obesity is associated with dyslipidemia, ectopic lipid deposition, and insulin resistance. In mice, the global or adipose-specific loss of function of the protein angiopoietin-like 4 (ANGPTL4) leads to decreased plasma triglyceride levels, enhanced adipose triglyceride uptake, and protection from high-fat diet (HFD)-induced glucose intolerance. ANGPTL4 is also expressed highly in the liver, but the role of liver-derived ANGPTL4 is unclear. The goal of this study was to determine the contribution of hepatocyte ANGPTL4 to triglyceride and glucose homeostasis in mice during a high-fat diet challenge. We generated hepatocyte-specific ANGPTL4 deficient (Angptl4^LivKO) mice, fed them a 60% kcal/fat diet (HFD) for 6 mo and assessed triglyceride, liver, and glucose metabolic phenotypes. We also explored the effects of prolonged fasting on Angptl4^LivKO mice. The loss of hepatocyte-derived ANGPTL4 led to no major changes in triglyceride partitioning or lipoprotein lipase activity compared with control mice. Interestingly, although there was no difference in fasting plasma triglyceride levels after a 6 h fast, after an 18-h fast, normal chow diet-fed Angptl4^LivKO mice had lower triglyceride levels than control mice. On a HFD, Angptl4^LivKO mice initially showed no difference in glucose tolerance and insulin sensitivity, but improved glucose tolerance emerged in these mice after 6 mo on HFD. Our data suggest that hepatocyte ANGPTL4 does not directly regulate triglyceride partitioning, but that loss of liver-derived ANGPTL4 may be protective from HFD-induced glucose intolerance and influence plasma triglyceride (TG) metabolism during prolonged fasting.NEW & NOTEWORTHY1) Angiopoietin-like 4 deficiency in hepatocytes (Angptl4^LivKO) does not improve triglyceride phenotypes during high-fat feeding. 2) Angptl4^LivKO mice have improved glucose tolerance after chronic high-fat diet. 3) Angptl4^LivKO mice have decreased fasting plasma triglyceride levels after an 18-h fast, but not after a 6-h fast.

Nonalcoholic fatty liver disease is a risk factor for glucose intolerance onset in men regardless of alanine aminotransferase status

INTRODUCTION

Fatty liver disease (FLD) is a surrogate condition for glucose intolerance development. FLD may involve normal or abnormal liver enzyme levels. Whether FLD is a risk factor for glucose intolerance, regardless of liver enzyme levels, remains unknown. We assessed relationships between the development of impaired fasting glucose (IFG) and FLD, liver enzyme abnormalities, and alcohol consumption.

MATERIALS AND METHODS

We retrospectively evaluated 8,664 participants with more than two annual health check-ups. Participants were classified according to sex, alcohol consumption, alanine aminotransferase (ALT) levels, and fatty liver status.

RESULTS

In univariate analyses, IFG onset among men was related to normal or high ALT levels with FLD in the nonalcoholic and alcoholic groups (P-trend < 0.01). In multivariate analyses, IFG onset among nonalcoholic men was associated with normal or high ALT levels with FLD, independent of potential confounding factors (P-trend < 0.01). However, IFG onset was non-independently associated with any condition among alcoholic men. In univariate analyses, IFG onset among women was related to normal or high ALT levels with FLD in the nonalcoholic group (P-trend < 0.01) and high ALT levels with FLD in the alcoholic group (P-trend < 0.05). In multivariate analyses, IFG onset was independently associated with only normal ALT levels in nonalcoholic FLD women.

CONCLUSIONS

Among nonalcoholic men and women, FLD was a risk factor for IFG onset, including normal ALT concentrations. Care is needed for individuals with nonalcoholic FLD, regardless of liver injury, possibly helping reduce glucose intolerance risk.

Distribution of normal and pathological OGTTs among pregnant population and non-pregnant women with PCOS - the cross-sectional study

Both pregnancy, as physiological, and polycystic ovary syndrome (PCOS), as a pathological condition, carry the risk for developing glucose metabolism abnormalities. In this retrospective cross-sectional study, we hypothesized that pregnancy as a physiological condition carries a higher likelihood for abnormal oral glucose tolerance test (OGTT) results than PCOS as a pathological condition.We have compared the prevalence and likelihood ratios for abnormal OGTT results between non-pregnant women with PCOS (Group A) and pregnant women at 24 to 28 weeks of gestation (Group B). Participants of both study groups underwent glucose tolerance testing with 75 g glucose OGTT. During the study period, 7411 women were tested, 3932 women encompassed Group A, and 3479 women comprised Group B.The numbers of yearly tested pregnant women and the corresponding proportion of tested women among all study participants have decreased during the study period, from 766 to 131 and 89.1% to 20.5%, respectively. Group A had a significantly lower prevalence (4.4%) of pathological OGTT results compared to Group B (8.1%). This has resulted in a 45.427 likelihood ratio (P < .001) for abnormal OGTT results in pregnant women compared to non-pregnant women with PCOS.We might conclude that pregnancy could have a more challenging influence on glucose metabolism and that carries higher risks for abnormal glucose metabolism than PCOS. The awareness of obstetricians regarding physiological changes during pregnancy that predisposes abnormal glucose metabolism is decreasing over time and the compliance concerning OGTT testing of pregnant women is decreasing too.

Prenatal androgen excess impairs beta-cell function by decreased sirtuin 3 expression

Prenatal androgen exposure induces metabolic disorders in female offspring. However, the long-term effect of maternal testosterone excess on glucose metabolism, especially on pancreatic beta-cell function, is rarely investigated. Our current study mainly focused on the effects of prenatal testosterone exposure on glucose metabolism and pancreatic beta- cell function in aged female offspring. By using maternal mice and their female offspring as animal models, we found that prenatal androgen treatment induced obesity and glucose intolerance in aged offspring. These influences were accompanied by decreased fasting serum insulin concentration, elevated serum triglyceride, and testosterone concentrations. Glucose stimulated insulin secretion in pancreatic beta cells of aged female offspring was also affected by prenatal testosterone exposure. We further confirmed that increased serum testosterone contributed to downregulation of sirtuin 3 expression, activated oxidative stress, and impaired pancreatic beta-cell function in aged female offspring. Moreover, over-expression of sirtuin 3 in islets isolated from female offspring treated with prenatal testosterone normalized the oxidative stress level, restored cyclic AMP, and ATP generation, which finally improved glucose-stimulated insulin secretion in beta cells. Taken together, these results demonstrated that prenatal testosterone exposure caused a metabolic disturbance in aged female offspring via suppression of sirtuin 3 expression and activation of oxidative stress in pancreatic beta cells.

Male and Female Rats Have Different Physiological Response to High-Fat High-Sucrose Diet but Similar Myocardial Sensitivity to Ischemia-Reperfusion Injury

Prediabetes is a strong predictor of type 2 diabetes and its associated cardiovascular complications, but few studies explore sexual dimorphism in this context. Here, we aim to determine whether sex influences physiological response to high-fat high-sucrose diet (HFS) and myocardial tolerance to ischemia-reperfusion injury. Male and female Wistar rats were subjected to standard (CTRL) or HFS diet for 5 months. Then, ex-vivo experiments on isolated perfused heart model were performed to evaluate tolerance to ischemia-reperfusion injury. HFS diet induced fasting hyperglycemia and increased body fat percent to a similar level in both sexes. However, glucose intolerance was more pronounced in female HFS. Cholesterol was increased only in female while male displayed higher level of plasmatic leptin. We observed increased heart weight to tibia length ratio only in males, but we showed a similar decrease in tolerance to ischemia-reperfusion injury in female and male HFS compared with respective controls, characterized by impaired cardiac function, energy metabolism and coronary flow during reperfusion. In conclusion, as soon as glucose intolerance and hyperglycemia develop, we observe higher sensitivity of hearts to ischemia-reperfusion injury without difference between males and females.

The effects of two types of Western diet on the induction of metabolic syndrome and cardiac remodeling in obese rats

Metabolic syndrome (MetS) include obesity as a critical feature and is strongly associated with risk of cardiovascular disease (CVD). Insights into mechanisms involved in the pathophysiology of these clinical manifestations are essential for the development of therapeutic strategies. Thus, Western diets (WD) have been widely employed in diet-induced obesity (DIO) model. However, there are variations in fat and sugar proportions of such diets, making comparisons challenging. We aimed to assess the impact of two types of the WD on metabolic status and cardiac remodeling, to achieve a DIO model that better mimics the human pathogenesis of MetS-induced CVD. Male Wistar rats were distributed into three groups: control diet, Western diet fat (WDF), and Western diet sugar (WDS) for 41 weeks. Metabolic and inflammatory parameters and cardiac changes were characterized. WDF and WDS feeding promoted higher serum triglycerides, glucose intolerance, and insulin resistance, while just WDF presented inflammation in adipose tissue. WDF-fed rats showed increased catalase activity and malondialdehyde (MDA) and carbonyl protein levels, suggesting cardiac oxidative stress, while WDS-fed rats only raised MDA. Both WD equally elevated protein expressions involved in lipid metabolism, but only WDF downregulated the glycolysis pathway. Furthermore, the mechanical myocardial function was impaired in obese rats, being more relevant in WDF. In conclusion, both WD effectively triggered MetS features, although inflammation was detected just on the WDF-fed animals. Moreover, the WDF promoted a more pronounced functional, metabolic, and oxidative cardiac disorder, suggesting to be an adequate model for studying CVD in the scenario of MetS.

Soluble guanylate cyclase chronic stimulation effects on cardiovascular reactivity in cafeteria diet-induced rat model of metabolic syndrome

Metabolic syndrome is linked to an increased risk of cardiovascular complications by a mechanism involving mainly decreased nitric oxide (NO) bioavailability and impaired NO-soluble guanylate cyclase (sGC)- cyclic guanosine monophosphate (cGMP) signalling (NO-sGC-cGMP). To further develop this scientific point, this study aimed to investigate the effects of long-term treatment with BAY 41-2272 (a sGC stimulator) on cardiovascular reactivity of spontaneously hypertensive rats (SHR) as a model of metabolic syndrome. SHR were randomly divided into 3 groups: control group, cafeteria diet (CD)-fed group and CD-fed group treated daily with BAY 41-2272 (5 mg/kg) by gastric gavage for 12 weeks. In vivo measurements of body weight, abdominal circumference, blood pressure and glucose tolerance test were performed. At the end of the feeding period, ex vivo cumulative concentration-response curves were performed on isolated perfused heart (isoproterenol (0.1 nM - 1 μM)) and thoracic aorta (phenylephrine (1 nM-10 μM), acetylcholine (1 nM-10 μM), and sodium nitroprusside (SNP) (0.1 nM-0.1 μM)). We showed that chronic CD feeding induced abdominal obesity, hypertriglyceridemia, glucose intolerance and exacerbated arterial hypertension in SHR. Compared to control group, CD-fed group showed a decrease in β-adrenoceptor-induced cardiac inotropy, in coronary perfusion pressure and in aortic contraction to phenylephrine. While relaxing effects of acetylcholine and SNP were unchanged. BAY 41-2272 long-term treatment markedly prevented arterial hypertension development and glucose intolerance, enhanced the α1-adrenoceptor-induced vasoconstriction, and restored cardiac inotropy and coronary vasodilation. These findings suggest that BAY 41-2272 may be a potential novel drug for preventing metabolic and cardiovascular complications of metabolic syndrome.

Effect of hypertriglyceridemia in dyslipidemia-induced impaired glucose tolerance and sex differences in dietary features associated with hypertriglyceridemia among the Japanese population: The Gifu Diabetes Study

AIMS/INTRODUCTION

The mechanisms underlying hypertriglyceridemia-induced impaired glucose tolerance in Japanese individuals remain unclear. We aimed to evaluate the effect of hypertriglyceridemia on glucose metabolism in comparison with that of increased low-density lipoprotein or decreased high-density lipoprotein levels and to elucidate the sex differences in hypertriglyceridemia-related dietary intake among Japanese individuals.

MATERIALS AND METHODS

We randomly selected 898 (384 men and 514 women) participants aged 40-78 years in the Gifu Diabetes Study; those taking medication for dyslipidemia or diabetes mellitus were excluded. Serum levels of glucose metabolism parameters and the food frequency were measured cross-sectionally. The glycated hemoglobin was measured again after 5 years.

RESULTS

Glucose metabolism parameters and the percentage of individuals with impaired glucose tolerance were significantly higher in the high triglyceride group in men and women. Similar trends were observed in the low high-density lipoprotein group, but only in men. Meanwhile, only the homeostasis model assessment of insulin resistance was higher in the high low-density lipoprotein group. In non-obese men, the percentage of energy intake from alcohol per total daily energy intake was significantly greater in the high triglyceride group. In obese women, the total energy intake was significantly greater in the high triglyceride group. At the 5-year follow up, the risk of elevated glycated hemoglobin levels with hypertriglyceridemia was increased in men.

CONCLUSIONS

Hypertriglyceridemia is a stronger risk factor for impaired glucose tolerance than increased low-density lipoprotein or decreased high-density lipoprotein. For dietary habits, increased daily alcohol energy intake in non-obese men and increased total energy intake in obese women were associated with hypertriglyceridemia.

Frequency of consumption of balanced meals, bodyweight gain and incident risk of glucose intolerance in Japanese men and women: A cohort study

AIMS/INTRODUCTION

This cohort study assessed the risk for bodyweight gain and development of glucose intolerance based on the frequency of consumption of balanced meals including grain, fish or meat and vegetables.

MATERIALS AND METHODS

The participants (8,573 men, 3,327 women) were employees of a company in Japan. A self-administered questionnaire was used to evaluate the frequency of balanced meal consumption. Bodyweight changes and the incidence of glucose intolerance (glycated hemoglobin >6.0%) during the 3-year follow-up period were determined through annual health examinations.

RESULTS

The mean bodyweight change over a period of 3 years was 0.78 kg for men and 0.84 kg for women. A lower frequency of balanced meals was associated with a higher bodyweight gain for men (P for trend = 0.004), but not for women. During the study, 464 men and 115 women developed glucose intolerance. Overall, the frequency of balanced meals was not associated with the risk of glucose intolerance in either sex. However, the interaction between the frequency of balanced meals and degree of obesity had a significant effect on the incidence of glucose intolerance in men (P = 0.005), with less frequent consumption of balanced meals being associated with a higher risk for glucose intolerance among men with a BMI ≥25.0 kg/m2 (P for trend = 0.007).

CONCLUSIONS

A higher frequency of balanced meals, including grain, fish or meat and vegetable dishes - important components of healthy Japanese food - was associated with a lower risk of glucose intolerance in obese men, but not in non-obese men and women.

Acute and long-term effects of saxagliptin on post-prandial glycemic response in obese patients with impaired glucose tolerance

BACKGROUND AND AIMS

Dipeptidyl-peptidase inhibitors might be useful in type 2 diabetes prevention. ACCES (ACute and Chronic Effects of Saxagliptin) was a randomized, placebo-controlled, double-blind, controlled phase 2, pilot study aiming to examine in obese patients with impaired glucose tolerance (IGT) the acute effects and the effects after 12 weeks of treatment by saxagliptin on glucose levels at fasting and postprandially after a standard breakfast, and on glucose tolerance.

METHODS AND RESULTS

We included 24 obese patients with IGT. Patients were randomized to receive saxagliptin 5 mg or placebo in the morning. The treatment was taken on Visit 1 before breakfast, then continued for 12 weeks. Biochemical measurements were performed before, one, two and three hours after a standard breakfast including 75 g of carbohydrates, during Visit 1 and Visit 2 (12 weeks). Glucose variability (GV) was evaluated at Visit 1 from 24-h continuous glucose monitoring including the breakfast. A second OGTT was performed at Visit 3 (3-5 days after Visit 2). Compared with placebo-treated patients, saxagliptin-treated patients had lower 1 h and 2 h post-meal plasma glucose levels at Visit 1 and similar changes at Visit 2 (p < 0.01 to p < 0.004), with lower GV indexes after breakfast at Visit 1. At Visit 3, all patients but one in saxagliptin group and only 4 patients in placebo group turned to normal glucose tolerance. Lower glucose response to breakfast at Visit 1 was predictive of recovery of glucose tolerance.

CONCLUSION

Saxagliptin has metabolically beneficial effects in glucose-intolerant obese patients by significantly lowering postprandial blood glucose levels.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01521312: https://clinicaltrials.gov/ct2/show/NCT01521312.

Glucose Tolerance Stages in Cystic Fibrosis Are Identified by a Unique Pattern of Defects of Beta-Cell Function

OBJECTIVE

We aimed to assess the order of severity of the defects of 3 direct determinants of glucose regulation-beta-cell function, insulin clearance, and insulin sensitivity-in patients with cystic fibrosis (CF), categorized according their glucose tolerance status, including early elevation of mid-level oral glucose tolerance test (OGTT) glucose values (>140 and <200 mg/dL), referred to as AGT140.

METHODS

A total of 232 CF patients aged 10 to 25 years underwent OGTT. Beta-cell function and insulin clearance were estimated by OGTT mathematical modeling and OGTT-derived biomarkers of insulin secretion and sensitivity were calculated. The association between glucometabolic variables and 5 glucose tolerance stages (normal glucose tolerance [NGT], AGT140, indeterminate glucose tolerance [INDET], impaired glucose tolerance [IGT], cystic fibrosis-related diabetes CFRD]) was assessed with a general linear model.

RESULTS

Beta-cell function and insulin sensitivity progressively worsened across glucose tolerance stages (P < 0.001), with AGT140 patients significantly differing from NGT (all P < 0.01). AGT140 and INDET showed a degree of beta-cell dysfunction similar to IGT and CFRD, respectively (all P < 0.01). Insulin clearance was not significantly associated with glucose tolerance stages (P = 0.162). Each stage of glucose tolerance was uniquely identified by a specific combination of defects of the direct determinants of glucose regulation.

CONCLUSIONS

In CF patients, each of the 5 glucose tolerance stages shows a unique pattern of defects of the direct determinants of glucose regulation, with AGT140 patients significantly differing from NGT and being similar to IGT. These findings suggest that AGT140 should be recognized as a distinct glucose tolerance stage and that reconsideration of the grade of glucometabolic deterioration across glucose tolerance stages in CF is warranted.

Fortifying Butterfat with Soybean Oil Attenuates the Onset of Diet-Induced Non-Alcoholic Steatohepatitis and Glucose Intolerance

The addition of plant oils such as soybean oil (S) to a diet rich in saturated fatty acids is discussed as a possible route to prevent or diminish the development of metabolic disease. Here, we assessed whether a butterfat-rich diet fortified with S affects the development of early non-alcoholic steatohepatitis (NASH) and glucose intolerance. Female C57BL/6J mice were fed a standard-control diet (C); a fat-, fructose-, and cholesterol-rich diet (FFC, 25E% butterfat, 50% (wt./wt.) fructose, 0.16% (wt./wt.) cholesterol); or FFC supplemented with S (FFC + S, 21E% butterfat + 4E% S) for 13 weeks. Indicators of liver damage, inflammation, intestinal barrier function, and glucose metabolism were measured. Lipopolysaccharide (LPS)-challenged J774A.1 cells were incubated with linolenic and linoleic acids (ratio 1:7.1, equivalent to S). The development of early NASH and glucose intolerance was significantly attenuated in FFC + S–fed mice compared to FFC-fed mice associated with lower hepatic toll-like receptor-4 mRNA expression, while markers of intestinal barrier function were significantly higher than in C-fed mice. Linolenic and linoleic acid significantly attenuated LPS-induced formation of reactive nitrogen species and interleukin-1 beta mRNA expression in J774A.1 cells. Our results indicate that fortifying butterfat with S may attenuate the development of NASH and glucose intolerance in mice.

Sex-specific effects of ketogenic diet after pre-exposure to a high-fat, high-sugar diet in rats

BACKGROUND AND AIMS

The objectives were to evaluate the relationship between ketogenic diets, the ketone body beta-hydroxybutyrate (BHB), parameters known to increase risk for cardiovascular and metabolic diseases in both sexes, using a pre-clinical model of obesity.

METHODS AND RESULTS

Rats had access to a diet high in fat and sugar (HFS) for 12 weeks. After HFS, they switched to chow (HFS-CH) or ketogenic diet (HFS-KD) for 3 weeks to model a dietary intervention. Body weight, adiposity, and food intake were measured. Glucose tolerance and corticosterone response to stress were measured after HFS, then again after the intervention. Both sexes increased body weight, food intake, and adiposity compared to control (CTL) while on HFS. HFS females showed impaired glucose tolerance. HFS males developed a dampened corticosterone to stress, whereas HFS females developed an exacerbated response. The effects of HFS on adiposity and corticosterone were reversed in HFS-CH males. These same improvements were observed in HFS-CH females, although they still had impaired glucose tolerance. HFS-KD males showed some improvements, however, they still had higher body weight and adiposity than CTL. The same pattern was observed in females. These beneficial effects of KD correlated with plasma BHB levels in females but not in males.

CONCLUSIONS

These data model effects reported in clinical literature and serve as a valuable translational tool to further test causal mechanisms that lead to desirable outcomes of KD. These sex-specific relationships are important, as KD could potentially affect endocrine mechanisms differently in males and females.

Silent pituitary adenoma and metabolic disorders: obesity, abnormal glucose tolerance, hypertension and dyslipidemia

A silent pituitary adenoma (SPA) is characterized by the expression of pituitary hormones, detected by immunohistochemical staining, in the absence of clinical signs or symptoms of hormonal excess. Compared with functional pituitary adenomas, little is known regarding the involvement of SPAs in metabolic disorders. This study aimed to examine the correlations between SPAs and metabolic disorders, including obesity, abnormal glucose tolerance, hypertension and dyslipidemia. Seventy-four patients with nonfunctional pituitary adenomas who underwent a pituitary adenomectomy in Hokkaido University Hospital from 2008 to 2016 were retrospectively examined. Pituitary adenomas were immunohistochemically classified into pituitary hormone positive or negative groups. Twenty whole hormone-negative pituitary adenomas were excluded because we couldn't identify pituitary transcription factors which is necessary for the diagnosis of a null cell adenoma. The preoperative rates of obesity, abnormal glucose tolerance, hypertension and dyslipidemia were compared between each group. Twenty-seven GH positive adenomas (50.0%), 32 gonadotroph positive adenomas (59.3%), 28 TSH positive adenomas (51.9%) and 21 ACTH positive adenomas (38.9%) were identified. Evaluation of the preoperative clinical data showed 25 cases of obesity (46.2%), 16 cases of abnormal glucose tolerance (29.6%), 29 cases of hypertension (53.7%) and 35 cases of dyslipidemia (64.8%). The rate of hypertension was significantly lower in the GH positive group (37.0%) than the GH negative group (70.4%) (p = 0.0140). In the GH negative group, postoperative systolic and diastolic blood pressure levels were significantly lower than preoperative values. GH positive SPAs may affect the homeostasis of blood pressure.

Glucose tolerance in a cohort of Egyptian children after kidney transplantation

BACKGROUND

Post- transplantation diabetes mellitus (PTDM) in children is a serious metabolic complication that can endanger both graft and patient survival. These complications can be partially reduced by early diagnosis & prompt treatment of impaired glucose tolerance. The aim of this study was to assess glucose tolerance & insulin resistance among a cohort of kidney transplanted children.

METHODS

Thirty consecutive pediatric kidney transplant recipients were subjected to basal evaluation of plasma glucose and insulin then underwent oral glucose tolerance test (OGTT).

RESULTS

Abnormal glucose metabolism was detected in 7 (23.3%) patients; 3 (10%) patients with PTDM; 3 (10%) patients with impaired fasting glucose (IFG) and 1 (3.3%) patient with IFG and impaired glucose tolerance (IGT). Four (13.3%) patients had high Homeostatic model assessment of insulin resistance (HOMA-IR). Patients with abnormal glucose metabolism had significantly higher tacrolimus trough levels and higher maintainence steroid doses (p values = 0.003,0.026). Significant positive correlation existed between pre-transplantation glucose level and post-transplantation fasting glucose (p = 0.001, r = 0.69), glucose at 120 min (p = 0.018, r = 0.429) and HOMA-IR (p = 0.008, r = 0.47).

CONCLUSION

Abnormalities in glucose metabolism (IFG, IGT &PTDM) are frequent in Egyptian pediatric kidney transplant recipients. OGTT is the gold standard for assessment of abnormalities in glucose metabolism.

Abnormal glucose tolerance in a pediatric cystic fibrosis cohort: Trends in clinical outcomes and associated factors in the preceding years

BACKGROUND AND AIMS

Deterioration of anthropometric and lung function parameters was shown to precede the onset of cystic fibrosis-related diabetes (CFRD) in adults. In children, studies have been conducted in small cohorts with relatively short observation period. Study objectives were to document the longitudinal trends of anthropometric, pulmonary, nutritional and metabolic parameters from cystic fibrosis (CF) diagnosis to the ascertainment of abnormal glucose tolerance and identify parameters associated with the incidence of such abnormalities in a pediatric CF cohort.

METHODS AND RESULTS

Retrospective cohort study of 281 children with CF. Longitudinal trends of anthropometric, lung function, nutritional and metabolic data were generated from CF diagnosis to the ascertainment of abnormal glucose tolerance defined as the presence of either impaired glucose tolerance (IGT), unconfirmed CFRD or CFRD. Cox models and Kaplan-Meier curves were used to identify factors associated with developing abnormal glucose tolerance. Forty-five percent of cohort had normal glucose tolerance (NGT), 27% IGT, 10% unconfirmed CFRD and 18% CFRD. Children who developed CFRD displayed lower height z-scores from a very early age. Conversely, HbA1c levels began to rise closer to CFRD ascertainment. Height z-scores (HR: 0.45; CI 95% [0.29-0.69]) and HbA1c (HR: 2.43; CI 95% [1.86-3.18]) in years preceding ascertainment were associated with the risk of developing CFRD.

CONCLUSION

Children who developed CFRD display distinctive trends for height z-scores from a very early age, whereas HbA1c appears as a marker of established glucose metabolism derangements.

Interleukin-1 Receptor-1 Deficiency Impairs Metabolic Function in Pregnant and Non-Pregnant Female Mice

SCOPE

Glucose intolerance during pregnancy is associated with short- and long-term maternal and offspring health consequences. In young male mice, knockout of the major pro-inflammatory mediator interleukin-1-receptor-1 (IL1R1) protects against high-fat diet (HFD)-induced glucose intolerance and metabolic dysfunction. This phenotype has not been examined during pregnancy. The hypothesis that IL1R1 depletion will protect females against HFD-induced glucose intolerance and metabolic dysfunction before, during, and post pregnancy is tested.

METHODS AND RESULTS

C57BL/6J control and IL1R1 knockout (IL1R1-/- ) mice are randomized to either a control diet (10% kcal from fat) or HFD (45% kcal from fat), and three distinct cohorts are established: nulliparous, pregnant, and postpartum females. Contrary to the authors' hypothesis, it is found that IL1R1-/- does not protect against glucose intolerance in nulliparous or pregnant females, and while control HFD animals see a resolution of glucose tolerance postpartum, IL-1R1-/- mice remain impaired. These effects are accompanied by adipocyte hypertrophy, hyperleptinemia, and increased adipose tissue inflammatory gene expression. Maternal genotype differentially affects fetal growth in male and female fetuses, demonstrating sexual dimorphism in this genotype prior to birth.

CONCLUSIONS

These findings suggest that IL1R1 signaling is important for normal metabolic functioning in females, during and outside of pregnancy.

The Association of Trp64Arg Polymorphism in the Beta-Adrenergic Receptor With Insulin Resistance: Meta-Analysis

BACKGROUND

Insulin resistance is a metabolic disorder that occurs in type 2 diabetes mellitus and obesity. Genetic factors such as β3-adrenoceptor polymorphism (Trp64Arg) may be involved in IR and insulin secretion. However, their association is controversial. Therefore, the current meta-analysis was conducted to clarify the relationship between the Trp64Arg and IR.

METHODS

The literature search was performed in PubMed, Embase, and Web of Science using the keywords "Receptors, Adrenergic, beta-3, Receptors, Adrenergic, Insulin Resistance, Protein-Coupled Receptor Kinase 3" from 2005 to February 7, 2021. We used a random-effects model to calculate the pooled effect size. We conducted subgroup analysis and regression analysis to identify sources of heterogeneity; and Egger's test and funnel plot were used to test publication bias. Finally, we conducted a sensitivity analysis.

RESULTS

We included eight papers with 1,586 subjects. There was a positive correlation between Trp64Arg mutation and insulin level (standardized mean difference = 0.20, 95% confidence intervals: 0.00 to 0.39, I² = 57.6%, p = 0.016). However, there was no association between Trp64Arg and the homeostasis model (HOMA-IR) assessment. Egger's tests showed no publication bias; the sensitivity analysis showed that our results were stable. Regression analysis revealed no source of heterogeneity.

CONCLUSION

Trp64Arg may be associated with IR. European ancestry, obesity, plasma insulin level, and test status may be potential factors affecting the relationship between Trp64Arg and IR.

Incidence and Risk Factors of Hypogonadism in Male Patients With Latent Autoimmune Diabetes and Classic Type 2 Diabetes

OBJECTIVES

This study aimed to compare the prevalence of hypogonadism between male patients with latent autoimmune diabetes (LADA) and type 2 diabetes (T2DM) and investigate the risk factors for hypogonadism in these patients.

METHODS

This cross-sectional study evaluated 367 male patients with LADA (n=73) and T2DM (n=294) who visited the endocrinology department of Shanghai Tenth People's Hospital between January 2016 and October 2019 for diabetes management. Sex hormones, lipid profiles, sex hormone-binding globulin (SHBG), glycosylated hemoglobin A1c, beta-cell function, uric acid, and osteocalcin were determined in serum samples. Hypogonadism was defined as calculated free testosterone (cFT) less than 220 pmol/L along with the presence of symptoms (positive ADAM score).

RESULTS

The rate of hypogonadism in the LADA and T2DM group were 8.2, and 21.7%, respectively (p=0.017). After adjusting possible confounders, the rate of hypogonadism in the LADA group was comparable to those of the T2DM group. Univariate logistic regressions demonstrated that age, BMI, fasting C-peptide, triglycerides, total cholesterol and uric acid were associated with hypogonadism in men with diabetes, BMI, triglycerides and estradiol were independent risk for hypogonadism in men with diabetes.

CONCLUSION

This is the first evidence to explore the rate of hypogonadism in male patients with latent autoimmune diabetes (LADA). In the population requiring admission to a large urban hospital in China, the rate of hypogonadism was comparable to those of the T2DM group after adjusting for possible confounders. BMI, triglycerides and estradiol were independently associated with the presence of HH in male diabetic patients.

Induction of Core Circadian Clock Transcription Factor Bmal1 Enhances β-Cell Function and Protects Against Obesity-Induced Glucose Intolerance

Type 2 diabetes mellitus (T2DM) is characterized by β-cell dysfunction as a result of impaired glucose-stimulated insulin secretion (GSIS). Studies show that β-cell circadian clocks are important regulators of GSIS and glucose homeostasis. These observations raise the question about whether enhancement of the circadian clock in β-cells will confer protection against β-cell dysfunction under diabetogenic conditions. To test this, we used an approach by first generating mice with β-cell-specific inducible overexpression of Bmal1 (core circadian transcription factor; β-Bmal1 ^OV ). We subsequently examined the effects of β-Bmal1 ^OV on the circadian clock, GSIS, islet transcriptome, and glucose metabolism in the context of diet-induced obesity. We also tested the effects of circadian clock-enhancing small-molecule nobiletin on GSIS in mouse and human control and T2DM islets. We report that β-Bmal1 ^OV mice display enhanced islet circadian clock amplitude and augmented in vivo and in vitro GSIS and are protected against obesity-induced glucose intolerance. These effects were associated with increased expression of purported BMAL1-target genes mediating insulin secretion, processing, and lipid metabolism. Furthermore, exposure of isolated islets to nobiletin enhanced β-cell secretory function in a Bmal1-dependent manner. This work suggests therapeutic targeting of the circadian system as a potential strategy to counteract β-cell failure under diabetogenic conditions.

Muscle-specific TGR5 overexpression improves glucose clearance in glucose-intolerant mice

TGR5, a G protein-coupled bile acid receptor, is expressed in various tissues and regulates several physiological processes. In the skeletal muscle, TGR5 activation is known to induce muscle hypertrophy; however, the effects on glucose and lipid metabolism are not well understood, despite the fact that the skeletal muscle plays a major role in energy metabolism. Here, we demonstrate that skeletal muscle-specific TGR5 transgenic (Tg) mice exhibit increased glucose utilization, without altering the expression of major genes related to glucose and lipid metabolism. Metabolite profiling analysis by capillary electrophoresis time-of-flight mass spectrometry showed that glycolytic flux was activated in the skeletal muscle of Tg mice, leading to an increase in glucose utilization. Upon long-term, high-fat diet challenge, blood glucose clearance was improved in Tg mice without an accompanying increase in insulin sensitivity in skeletal muscle and a reduction of body weight. Moreover, Tg mice showed improved age-associated glucose intolerance. These results strongly suggest that TGR5 ameliorated glucose metabolism disorder that is caused by diet-induced obesity and aging by enhancing the glucose metabolic capacity of the skeletal muscle. Our study demonstrates that TGR5 activation in the skeletal muscle is effective in improving glucose metabolism and may be beneficial in developing a novel strategy for the prevention or treatment of hyperglycemia.

Toward targeted prevention: risk factors for prediabetes defined by impaired fasting glucose, impaired glucose tolerance and increased HbA1c in the population-based KORA study from Germany

AIMS

To identify socioeconomic, behavioral and clinical factors that are associated with prediabetes according to different prediabetes definition criteria.

METHODS

Analyses use pooled data of the population-based Cooperative Health Research in the Region of Augsburg (KORA) studies (n = 5312 observations aged ≥ 38 years without diabetes). Prediabetes was defined through either impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or elevated HbA1c according to thresholds of the American Diabetes Association. Explanatory variables were regressed on prediabetes using generalized estimating equations.

RESULTS

Mean age was 58.4 years; 50% had prediabetes (33% had IFG, 16% IGT, and 26% elevated HbA1c, 10% fulfilled all three criteria). Age, obesity, hypertension, low education, unemployment, statutory health insurance, urban residence and physical inactivity were associated with prediabetes. Male sex was a stronger risk factor for IFG (OR = 2.5; 95%-CI: 2.2-2.9) than for IGT or elevated HbA1c, and being unemployed was a stronger risk factor for IGT (OR = 3.2 95%-CI: 2.6-4.0) than for IFG or elevated HbA1c.

CONCLUSIONS

The overlap of people with IFG, IGT and elevated HbA1c is small, and some factors are associated with only one criterion. Knowledge on sociodemographic and socioeconomic risk factors can be used to effectively target interventions to people at high risk for type 2 diabetes.

Animal and Cellular Studies Demonstrate Some of the Beneficial Impacts of Herring Milt Hydrolysates on Obesity-Induced Glucose Intolerance and Inflammation

The search for bioactive compounds from enzymatic hydrolysates has increased in the last few decades. Fish by-products have been shown to be rich in these valuable molecules; for instance, herring milt is a complex matrix composed of lipids, nucleotides, minerals, and proteins. However, limited information is available on the potential health benefits of this by-product. In this context, three industrial products containing herring milt hydrolysate (HMH) were tested in both animal and cellular models to measure their effects on obesity-related metabolic disorders. Male C57Bl/6J mice were fed either a control chow diet or a high-fat high-sucrose (HFHS) diet for 8 weeks and received either the vehicle (water) or one of the three HMH products (HMH1, HMH2, and HMH3) at a dose of 208.8 mg/kg (representing 1 g/day for a human) by daily oral gavage. The impact of HMH treatments on insulin and glucose tolerance, lipid homeostasis, liver gene expression, and the gut microbiota profile was studied. In parallel, the effects of HMH on glucose uptake and inflammation were studied in L6 myocytes and J774 macrophages, respectively. In vivo, daily treatment with HMH2 and HMH3 improved early time point glycemia during the oral glucose tolerance test (OGTT) induced by the HFHS diet, without changes in weight gain and insulin secretion. Interestingly, we also observed that HMH2 consumption partially prevented a lower abundance of Lactobacillus species in the gut microbiota of HFHS diet-fed animals. In addition to this, modulations of gene expression in the liver, such as the upregulation of sucrose nonfermenting AMPK-related kinase (SNARK), were reported for the first time in mice treated with HMH products. While HMH2 and HMH3 inhibited inducible nitric oxide synthase (iNOS) induction in J774 macrophages, glucose uptake was not modified in L6 muscle cells. These results indicate that milt herring hydrolysates reduce some metabolic and inflammatory alterations in cellular and animal models, suggesting a possible novel marine ingredient to help fight against obesity-related immunometabolic disorders.

Metabolic Defects Caused by High-Fat Diet Modify Disease Risk through Inflammatory and Amyloidogenic Pathways in a Mouse Model of Alzheimer's Disease

High-fat diet (HFD) has been shown to accelerate Alzheimer’s disease (AD) pathology, but the exact molecular and cellular mechanisms remain incompletely understood. Moreover, it is unknown whether AD mice are more susceptible to HFD-induced metabolic dysfunctions. To address these questions, we used 5xFAD mice as an Alzheimer’s disease model to study the physiological and molecular underpinning between HFD-induced metabolic defects and AD pathology. We systematically profiled the metabolic parameters, the gut microbiome composition, and hippocampal gene expression in 5xFAD and wild type (WT) mice fed normal chow diet and HFD. HFD feeding impaired energy metabolism in male 5xFAD mice, leading to increased locomotor activity, energy expenditure, and food intake. 5xFAD mice on HFD had elevated circulating lipids and worsened glucose intolerance. HFD caused profound changes in gut microbiome compositions, though no difference between genotype was detected. We measured hippocampal mRNAs related to AD neuropathology and neuroinflammation and showed that HFD elevated the expression of apoptotic, microglial, and amyloidogenic genes in 5xFAD mice. Pathway analysis revealed that differentially regulated genes were involved in insulin signaling, cytokine signaling, cellular stress, and neurotransmission. Collectively, our results showed that 5xFAD mice were more susceptible to HFD-induced metabolic dysregulation and suggest that targeting metabolic dysfunctions can ameliorate AD symptoms via effects on insulin signaling and neuroinflammation in the hippocampus.