Fasting for 48 h induced similar glucose intolerance in both sexes despite greater perceived stress and decreased estradiol levels in females.

PURPOSE: The purpose of this study was to compare the effects of fasting for 48 h on the evoked insulin and glucose responses in males and females, and to explore factors such as stress and estrogen levels that might influence these responses. METHODS: Healthy, nonobese male (n = 14) and female (n = 14) subjects underwent 48-h fasting trial. Changes in glucose tolerance and insulin levels in response to the oral glucose tolerance test, subjectively perceived stress and catecholamine concentrations were measured in all participants. Estrogen levels were also measured in the female participants during the 48-h fast. RESULTS: Glucose area under the curve (AUC) values increased similarly in both sexes after 48-h fasting (P < 0.05), but females displayed a greater rise in insulin AUC values than males (P < 0.05). Fasting increased plasma epinephrine concentrations in both sexes (P < 0.05), whereas plasma norepinephrine concentrations and subjective stress increased only in females (P < 0.05). Plasma 17-ß-estradiol concentrations in females decreased after fasting (P < 0.05). CONCLUSION: Fasting for 48 h induced a similar glucose intolerance in females and males, despite decreased 17-ß-estradiol levels and greater psychological and physiological stress in females. These differences represent a plausible explanation for the gender-based differences observed in insulin responses. TRIAL REGISTRATION: Retrospectively registered on ClinicalTrials.gov (NCT05545943) in September 19, 2022.

Profile of Daughters and Sisters of Women With Polycystic Ovary Syndrome: The Role of Proband's Glucose Tolerance.

CONTEXT: First-degree relatives of women with polycystic ovary syndrome (PCOS) present hormonal and metabolic alterations compared to girls unrelated to PCOS. It is unknown whether glucose intolerance in the PCOS proband confers a more severe metabolic predisposition on their first-degree relatives. OBJECTIVE: To determine whether glucose tolerance status in women with PCOS is associated with worsened glucose metabolism and sex hormone levels in their peripubertal daughters or sisters. DESIGN: Cross-sectional study. SETTING: Seven academic centers in North America, South America, and Europe. PATIENTS: Sixty-four pairs of women with PCOS and their daughters or younger sisters aged between 8 and 14 years were recruited. Twenty-five mothers or older sisters with PCOS were glucose intolerant (GI) and 39 were normal glucose tolerant (NGT). MAIN OUTCOME MEASURES: Beta-cell function estimated by the insulin secretion-sensitivity index-2 (ISSI-2) during an oral glucose tolerance test and by the disposition index during a frequently sampled IV glucose tolerance test. Free testosterone and 17-hydroxyprogesterone (17-OHP) levels. RESULTS: Being related to a GI PCOS proband was associated with a lower ISSI-2 (P-value = 0.032) after adjusting for ethnicity, body mass index z-score, and pubertal stage. They also had higher free testosterone (P-value = 0.011) and 17-OHP levels compared to girls with an NGT proband, the latter becoming significant after adjusting for confounders (P-value = 0.040). CONCLUSIONS: Compared to first-degree female relatives of women with PCOS and NGT, first-degree relatives of women with PCOS and GI display lower beta-cell function and hyperandrogenemia, putting them at higher risk of GI and PCOS development.

Nicotinamide Mononucleotide Prevents Free Fatty Acid-Induced Reduction in Glucose Tolerance by Decreasing Insulin Clearance.

The NAD-dependent deacetylase SIRT1 improves ß cell function. Accordingly, nicotinamide mononucleotide (NMN), the product of the rate-limiting step in NAD synthesis, prevents ß cell dysfunction and glucose intolerance in mice fed a high-fat diet. The current study was performed to assess the effects of NMN on ß cell dysfunction and glucose intolerance that are caused specifically by increased circulating free fatty acids (FFAs). NMN was intravenously infused, with or without oleate, in C57BL/6J mice over a 48-h-period to elevate intracellular NAD levels and consequently increase SIRT1 activity. Administration of NMN in the context of elevated plasma FFA levels considerably improved glucose tolerance. This was due not only to partial protection from FFA-induced ß cell dysfunction but also, unexpectedly, to a significant decrease in insulin clearance. However, in conditions of normal FFA levels, NMN impaired glucose tolerance due to decreased ß cell function. The presence of this dual action of NMN suggests caution in its proposed therapeutic use in humans.

Lipidomic changes of LDL after consumption of Camelina sativa oil, fatty fish and lean fish in subjects with impaired glucose metabolism-A randomized controlled trial.

BACKGROUND: There is little knowledge on the effects of alpha-linolenic acid (ALA) and n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) on the LDL lipidome and aggregation of LDL particles. OBJECTIVE: We examined if consumption of Camelina sativa oil (CSO) as a source of ALA, fatty fish (FF) as a source of n-3 LCPUFA and lean fish (LF) as a source of fish protein affect the lipidome of LDL as compared to a control diet. METHODS: Participants with impaired glucose tolerance (39 women and 40 men) were randomized to 4 study groups (CSO providing 10 g/d ALA, FF and LF [both 4 fish meals/wk] and control limiting their fish and ALA intake) in a 12-week, parallel trial. Diets were instructed and dietary fats were provided to the participants. The lipidome of LDL particles isolated from samples collected at baseline and after intervention was analyzed with electrospray ionization-tandem mass spectrometry. RESULTS: In the CSO group, the relative concentrations of saturated and monounsaturated cholesteryl ester species in LDL decreased and the species with ALA increased. In the FF group, LDL phosphatidylcholine (PC) species containing n-3 LCPUFA increased. There was a significant positive correlation between the change in total sphingomyelin and change in LDL aggregation, while total PC and triunsaturated PC species were inversely associated with LDL aggregation when all the study participants were included in the analysis. CONCLUSION: Dietary intake of CSO and FF modifies the LDL lipidome to contain more polyunsaturated and less saturated lipid species. The LDL surface lipids are associated with LDL aggregation.

Trans Fatty Acid Intake Induces Intestinal Inflammation and Impaired Glucose Tolerance.

Background and Aims: Many nutritional and epidemiological studies have shown that high consumption of trans fatty acids can cause several adverse effects on human health, including cardiovascular disease, diabetes, and cancer. In the present study, we investigated the effect of trans fatty acids on innate immunity in the gut by observing mice fed with a diet high in trans fatty acids, which have been reported to cause dysbiosis. Methods: We used C57BL6/J mice and fed them with normal diet (ND) or high-fat, high-sucrose diet (HFHSD) or high-trans fatty acid, high-sucrose diet (HTHSD) for 12 weeks. 16S rRNA gene sequencing was performed on the mice stool samples, in addition to flow cytometry, real-time PCR, and lipidomics analysis of the mice serum and liver samples. RAW264.7 cells were used for the in vitro studies. Results: Mice fed with HTHSD displayed significantly higher blood glucose levels and advanced fatty liver and intestinal inflammation, as compared to mice fed with HFHSD. Furthermore, compared to mice fed with HFHSD, mice fed with HTHSD displayed a significant elevation in the expression of CD36 in the small intestine, along with a reduction in the expression of IL-22. Furthermore, there was a significant increase in the populations of ILC1s and T-bet-positive ILC3s in the lamina propria in mice fed with HTHSD. Finally, the relative abundance of the family Desulfovibrionaceae, which belongs to the phylum Proteobacteria, was significantly higher in mice fed with HFHSD or HTHSD, than in mice fed with ND; between the HFHSD and HTHSD groups, the abundance was slightly higher in the HTHSD group. Conclusions: This study revealed that compared to saturated fatty acid intake, trans fatty acid intake significantly exacerbated metabolic diseases such as diabetes and fatty liver.

Using metabolic markers to identify insulin resistance in premenopausal women with and without polycystic ovary syndrome.

BACKGROUND: Insulin resistance (IR) is associated with increased risk for type 2 diabetes mellitus and cardiovascular disease. Quantifying IR is invasive and time-consuming, and thus not routinely used in clinical practice. Simple metabolic markers to predict IR exist, but have not been validated in premenopausal women or women with polycystic ovary syndrome (PCOS). OBJECTIVE: To evaluate the ability of metabolic markers to identify premenopausal women with/without PCOS who are insulin resistant. DESIGN/SETTING: Cross-sectional analysis. PARTICIPANTS: One hundred and seventy-one non-diabetic premenopausal overweight/obese women without PCOS and 71 women with PCOS. METHODS: IR was quantified by the steady-state plasma glucose during the modified insulin-suppression test. Metabolic markers (BMI, lipid/lipoprotein concentrations, and fasting glucose) were evaluated for their discriminative ability to identify IR, using area under the receiver-operating-characteristic curve (AUROC) analysis. Optimal cut-points were evaluated for predictive power. RESULTS: In the non-PCOS group, the triglyceride/HDL cholesterol ratio (TG/HDL-C) was the best marker (AUROC 0.73). Optimal diagnostic cut-point was 1.9. In the PCOS group, the TG/HDL-C ratio, cholesterol/HDL-C ratio (TC/HDL-C), and HDL-C performed well (AUROC > 0.80), with optimal cut-points for TG/HDL-C 1.3, TC/HDL-C 3.4, and HDL-C 52 mg/dL: TG/HDL-C was more sensitive, but HDL-C had a higher PPV for IR. CONCLUSION: TG/HDL-C can identify IR in premenopausal women with and/without PCOS; diagnostic cut-points differ from those of men and postmenopausal women. HDL-C is an alternative predictor in women with PCOS. These simple metabolic markers, which are standardized between labs, inexpensive, and routinely measured, can be used to tailor lifestyle and medical interventions to improve health outcomes in insulin-resistant premenopausal women.

A single-arm, open-label, intervention study to investigate the improvement of glucose tolerance after administration of the 5-aminolevulinic acid (5-ALA) in the patients with mitochondrial diabetes mellitus.

BACKGROUND: Mitochondrial diabetes mellitus (MDM) is characterized by maternal inheritance, progressive neurosensory deafness, insulin secretory disorder, and progressive microvascular complications. Mitochondria are critical organelles that provide energy in the form of adenosine triphosphate (ATP). An impairment of ATP production in pancreatic ß cells is regarded as the main cause of the insulin secretory disorder in patients with MDM, and these patients require insulin replacement therapy early after the diagnosis. The amino acid 5-aminolevulinic acid (5-ALA), a precursor of heme metabolites, is a non-proteinogenic δ amino acid synthesized in mitochondria. An addition of ferrous iron to 5-ALA enhances heme biosynthesis and increases ATP production through an upregulation of the respiratory complex. Several studies have reported that the administration of 5-ALA and ferrous iron to existing treatment improved the glycemic control in both patients with prediabetes and those with type 2 diabetes mellitus. The additional administration of 5-ALA and ferrous iron to MDM patients on insulin therapy may improve their insulin secretory capacity and glycemic control by improving their mitochondrial function. The findings of this study are expected to provide new treatment options for MDM and improve the patients' glycemic control and prognosis. METHODS/DESIGN: This study is a single-arm, open-label pilot intervention study using clinical endpoints to investigate the effects of treatment with 5-ALA plus sodium ferrous citrate (SFC) to patients with MDM on their glucose tolerance. A total of 5 patients with MDM will be administered 5-ALA/SFC (200 mg/d) for 24 weeks. We will perform a 75-g oral glucose tolerance test before and at 24 weeks after the start of this 5-ALA/SFC treatment to evaluate glucose-dependent insulin responses. DISCUSSION: To the best of our knowledge, this study will be the first assessment of the effects of 5-ALA/SFC in patients with MDM. This study will obtain an evidence regarding the effectiveness and safety of 5-ALA/SFC for patients with MDM. TRIAL REGISTRATION: This study was registered with the University Hospital Medical Information Network (UMIN000040581) on July 1, 2020 and with the Japan Registry of Clinical Trials (jRCTs071200025) on August 3, 2020.

Adeno-Associated Virus-Mediated Knockdown of SLC16A11 Improves Glucose Tolerance and Hepatic Insulin Signaling in High Fat Diet-Fed Mice.

BACKGROUND: SLC16A11, a member of the SLC16 family, is associated with lipid metabolism, causing increased intracellular triacylglycerol (TAG) levels. In the current study, our primary goal was to determine if an SLC16A11 knockdown would improve glucose tolerance and hepatic insulin signaling in high fat diet (HFD)-fed mice. Additionally, the mechanism for exercise-improved insulin sensitivity remains unclear, and there is no mechanistic insight into SLC16A11's role in insulin sensitivity under exercise stress. Therefore, we also examined the impact of endurance exercise on the abundance of SLC16A11. METHODS: C57BL/6 J male mice were fed either regular chow (Control) or HFD for 8 weeks and then injected with adeno-associated virus (AAV). Plasma parameters, tissue lipid contents, glucose tolerance, and expression profiles of hepatic insulin signaling were detected. Also, other mice were divided randomly into sedentary and exercise groups. We assessed hepatic expression of SLC16A11 after 8 weeks of endurance exercise. RESULTS: 1) Hepatic SLC16A11 expression was greater in HFD-fed mice compared to Control mice. 2) AAV-mediated knockdown of SLC16A11 improved glucose tolerance, prevented TAG accumulation in serum and liver, and increased phosphorylation of protein kinase B (Akt) and glycogen synthesis kinase-3ß (GSK3ß) in HFD-fed mice. 3) Endurance exercise decreased hepatic SLC16A11 expression. CONCLUSIONS: Inactivation of SLC16A11, which is robustly induced by HFD, improved glucose tolerance and hepatic insulin signaling, independent of body weight, but related to TAG. Additionally, SLC16A11 might mediate the health benefits of endurance exercise.

Improvement in Glycemic Control in Mice of Different Age Groups.

AIMS AND METHODS: The declining ability to control blood glucose with advancement of age is an important health risk factor and may lead to insulin resistance, type-2-diabetes and Alzheimer's disease. Adenovirus 36(Ad36) improves glycemic control independent of insulin signaling(insulin sparing effect) as evidenced by cell, animal and observational human studies. This property of Ad36 may be useful in correcting aging-related glucose intolerance and related health conditions. Therefore, we determined the effect of Ad36 on glycemic control in older mice, to identify the age group that best responds to Ad36. Six, 12 or 20-month old C57Bl/6 mice on chow diet were each divided into weight-matched groups(mock-infected or Ad36-infected). Body weight was recorded weekly post infection (p.i.) and fasting glucose measured(week 0, 4, 8 and 20 p.i.). Blood glucose and serum insulin were measured during glucose tolerance test(week 0 and 16 p.i.). At week 20 p.i., animals were sacrificed, blood and tissues collected. RESULTS: Mice from all age groups showed improvement in glucose clearance post Ad36 infection, but a more profound effect was observed in 6-month old mice compared with mock-infected mice. Under fed conditions though there was no difference in blood glucose at 20 wk p.i., interestingly, Ad36 reduced serum insulin in age groups old mice, compared with control mice. CONCLUSIONS: These findings suggest Ad36 infected animals improve glycemic control and clear post-prandial gluco00000se increase without increasing insulin secretion in an insulin sparing manner. These beneficial effects provide strong evidence for developing Ad36-based approaches as a novel tool to attenuate age associated glucose intolerance.

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.

Exenatide, Metformin, or Both for Prediabetes in PCOS: A Randomized, Open-label, Parallel-group Controlled Study.

CONTEXT: Up to 40% of patients with polycystic ovary syndrome (PCOS) have prediabetes; an optimal pharmacotherapy regimen for diabetes prevention in PCOS is yet to be established. OBJECTIVE: To evaluate clinical efficacy of exenatide (EX), metformin (MET), or combination (COM) for prediabetes in PCOS. DESIGN: Randomized, open-label, parallel-group controlled trial. SETTING: Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine. PATIENTS: PCOS with prediabetes (fasting plasma glucose 5.6-6.9 mmol/L and/or 2 hour post glucose 7.8-11.0 mmol/L on oral glucose tolerance test [OGTT]). A total of 150 out of 183 eligible enrollees completed the study. INTERVENTION: EX (10-20µg daily), MET (1500-2000 mg daily), or COM (EX plus MET) for 12 weeks. MAIN OUTCOME MEASURES: Sustained remission rate of prediabetes (primary endpoint, a normal OGTT after 12 weeks of treatment followed by 12 weeks of washout on no drug treatment) along with anthropometric, hormonal, metabolic, and pancreatic ß-cell function parameters (secondary endpoints) and potential mechanisms were assessed. RESULTS: Impaired glucose tolerance was found the dominant prediabetes phenotype. Overall sustained prediabetes remission rate was 50.7%. Remission rate of COM group (64%, 32/50) or EX group (56%, 28/50) was significantly higher than that of the MET group (32%, 16/50) (P = .003 and .027, respectively). EX was associated with superior suppression of 2-hour glucose increment in OGTT. A 2-step hyperglycemic clamp study revealed that EX had led to higher postprandial insulin secretion than MET, potentially explaining the higher remission rate. CONCLUSIONS: Compared with MET monotherapy, EX or COM achieved higher rate of remission of prediabetes among PCOS patients by improving postprandial insulin secretion.

Endothelial TFEB (Transcription Factor EB) Improves Glucose Tolerance via Upregulation of IRS (Insulin Receptor Substrate) 1 and IRS2.

OBJECTIVE: Vascular endothelial cells (ECs) play a critical role in maintaining vascular homeostasis. Aberrant EC metabolism leads to vascular dysfunction and metabolic diseases. TFEB (transcription factor EB), a master regulator of lysosome biogenesis and autophagy, has protective effects on vascular inflammation and atherosclerosis. However, the role of endothelial TFEB in metabolism remains to be explored. In this study, we sought to investigate the role of endothelial TFEB in glucose metabolism and underlying molecular mechanisms. Approach and Results: To determine whether endothelial TFEB is critical for glucose metabolism in vivo, we utilized EC-selective TFEB knockout and EC-selective TFEB transgenic mice fed a high-fat diet. EC-selective TFEB knockout mice exhibited significantly impaired glucose tolerance compared with control mice. Consistently, EC-selective TFEB transgenic mice showed improved glucose tolerance. In primary human ECs, small interfering RNA-mediated TFEB knockdown blunts Akt (AKT serine/threonine kinase) signaling. Adenovirus-mediated overexpression of TFEB consistently activates Akt and significantly increases glucose uptake in ECs. Mechanistically, TFEB upregulates IRS1 and IRS2 (insulin receptor substrate 1 and 2). TFEB increases IRS2 transcription measured by reporter gene and chromatin immunoprecipitation assays. Furthermore, we found that TFEB increases IRS1 protein via downregulation of microRNAs (miR-335, miR-495, and miR-548o). In vivo, Akt signaling in the skeletal muscle and adipose tissue was significantly impaired in EC-selective TFEB knockout mice and consistently improved in EC-selective TFEB transgenic mice on high-fat diet. CONCLUSIONS: Our data revealed a critical role of TFEB in endothelial metabolism and suggest that TFEB constitutes a potential molecular target for the treatment of vascular and metabolic diseases.

Testosterone treatment to prevent or revert type 2 diabetes in men enrolled in a lifestyle programme (T4DM): a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial.

BACKGROUND: Men who are overweight or obese frequently have low serum testosterone concentrations, which are associated with increased risk of type 2 diabetes. We aimed to determine whether testosterone treatment prevents progression to or reverses early type 2 diabetes, beyond the effects of a community-based lifestyle programme. METHODS: T4DM was a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial done at six Australian tertiary care centres. Men aged 50-74 years, with a waist circumference of 95 cm or higher, a serum testosterone concentration of 14·0 nmol/L or lower but without pathological hypogonadism, and impaired glucose tolerance (oral glucose tolerance test [OGTT] 2-h glucose 7·8-11·0 mmol/L) or newly diagnosed type 2 diabetes (provided OGTT 2-h glucose ≤15·0 mmol/L) were enrolled in a lifestyle programme and randomly assigned (1:1) to receive an intramuscular injection of testosterone undecanoate (1000 mg) or placebo at baseline, 6 weeks, and then every 3 months for 2 years. Randomisation was done centrally, including stratification by centre, age group, waist circumference, 2-h OGTT glucose, smoking, and first-degree family history of type 2 diabetes. The primary outcomes at 2 years were type 2 diabetes (2-h OGTT glucose ≥11·1 mmol/L) and mean change from baseline in 2-h OGTT glucose, assessed by intention to treat. For safety assessment, we did a masked monitoring of haematocrit and prostate-specific antigen, and analysed prespecified serious adverse events. This study is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000287831. FINDINGS: Between Feb 5, 2013, and Feb 27, 2017, of 19 022 men who were pre-screened, 1007 (5%) were randomly assigned to the placebo (n=503) and testosterone (n=504) groups. At 2 years, 2-h glucose of 11·1 mmol/L or higher on OGTT was reported in 87 (21%) of 413 participants with available data in the placebo group and 55 (12%) of 443 participants in the testosterone group (relative risk 0·59, 95% CI 0·43 to 0·80; p=0·0007). The mean change from baseline 2-h glucose was -0·95 mmol/L (SD 2·78) in the placebo group and -1·70 mmol/L (SD 2·47) in the testosterone group (mean difference -0·75 mmol/L, -1·10 to -0·40; p<0·0001). The treatment effect was independent of baseline serum testosterone. A safety trigger for haematocrit greater than 54% occurred in six (1%) of 484 participants in the placebo group and 106 (22%) of 491 participants in the testosterone group, and a trigger for an increase of 0·75 µg/mL or more in prostate-specific antigen occurred in 87 (19%) of 468 participants in the placebo group and 109 (23%) of 480 participants in the testosterone group. Prespecified serious adverse events occurred in 37 (7·4%, 95% CI 5·4 to 10·0) of 503 patients in the placebo group and 55 (10·9%, 8·5 to 13·9) of 504 patients in the testosterone group. There were two deaths in each group. INTERPRETATION: Testosterone treatment for 2 years reduced the proportion of participants with type 2 diabetes beyond the effects of a lifestyle programme. Increases in haematocrit might be treatment limiting. Longer-term durability, safety, and cardiovascular effects of the intervention remain to be further investigated. FUNDING: Australian National Health and Medical Research Council, Bayer, Eli Lilly, University of Adelaide, and WW (formerly Weight Watchers).

Limitations of the fasting proinsulin to insulin ratio as a measure of ß-cell health in people with and without impaired glucose tolerance.

BACKGROUND: The fasting proinsulin to insulin ratio is elevated in people with type 2 diabetes and has been suggested as a marker of ß-cell health. However, its utility in discriminating between individuals with varying degrees of ß-cell dysfunction is unclear. Proinsulin has a very different half-life to insulin and unlike insulin does not undergo hepatic extraction prior to reaching the systemic circulation. Given these limitations, we sought to examine the relationship between fasting and postprandial concentrations of ß-cell polypeptides (proinsulin, insulin and C-peptide) in people with normal and impaired glucose tolerance in differing metabolic environments. DESIGN: Subjects were studied on two occasions in random order while undergoing an oral challenge. During one study day, free fatty acids were elevated (to induce insulin resistance) by infusion of Intralipid with heparin. Proinsulin to insulin and proinsulin to C-peptide ratios were calculated for the 0-, 30-, 60- and 240-minute time points. Insulin action (Si) and ß-cell responsivity (Φ) indices were calculated using the oral minimal model. RESULTS: The fasting proinsulin to c-peptide or fasting proinsulin to insulin ratios did not differ between groups and did not predict subsequent ß-cell responsivity to glucose during the glycerol or Intralipid study days in either group. CONCLUSIONS: Among nondiabetic individuals, the fasting proinsulin to insulin ratio is not a useful marker of ß-cell function.

ILRUN, a Human Plasma Lipid GWAS Locus, Regulates Lipoprotein Metabolism in Mice.

RATIONALE: Single-nucleotide polymorphisms near the ILRUN (inflammation and lipid regulator with ubiquitin-associated-like and NBR1 [next to BRCA1 gene 1 protein]-like domains) gene are genome-wide significantly associated with plasma lipid traits and coronary artery disease (CAD), but the biological basis of this association is unknown. OBJECTIVE: To investigate the role of ILRUN in plasma lipid and lipoprotein metabolism. METHODS AND RESULTS: ILRUN encodes a protein that contains a ubiquitin-associated-like domain, suggesting that it may interact with ubiquitinylated proteins. We generated mice globally deficient for Ilrun and found they had significantly lower plasma cholesterol levels resulting from reduced liver lipoprotein production. Liver transcriptome analysis uncovered altered transcription of genes downstream of lipid-related transcription factors, particularly PPARα (peroxisome proliferator-activated receptor alpha), and livers from Ilrun-deficient mice had increased PPARα protein. Human ILRUN was shown to bind to ubiquitinylated proteins including PPARα, and the ubiquitin-associated-like domain of ILRUN was found to be required for its interaction with PPARα. CONCLUSIONS: These findings establish ILRUN as a novel regulator of lipid metabolism that promotes hepatic lipoprotein production. Our results also provide functional evidence that ILRUN may be the casual gene underlying the observed genetic associations with plasma lipids at 6p21 in human.

Hypoglycemia in cystic fibrosis during an extended oral glucose tolerance test.

BACKGROUND: Hypoglycemia in cystic fibrosis (CF), in the absence of glucose-lowering therapies, has long been identified as an important issue in the management of CF. There is currently still no unifying hypothesis for its etiology. AIM: The aims of this study were to perform a 3-h oral glucose tolerance test (OGTT) in participants with CF and (1) document glucose, insulin, glucagon, glucagon-like-peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) release patterns within varying glucose tolerance groups during the OGTT; (2) determine the prevalence of hypoglycemic during the OGTT; and (3) define any association between hypoglycemia and patterns of insulin, glucagon, GLP-1, and GIP release. METHODS: Eligible participants attending an adult CF clinic completed a 3-h OGTT. Hypoglycemia on OGTT was defined as mild (glucose 3.4-3.9 mmol/L), moderate (glucose 3.1-3.3 mmol/L), and severe (glucose ≤ 3 mmol/L). Hormones were measured at fasting, 30, 60, 120, and 180 min. RESULTS: Twenty-four participants completed the study, of which 7 had normal glucose tolerance, 12 had abnormal glucose tolerance, and 5 had cystic fibrosis related diabetes (CFRD). All participants had a delayed insulin response compared with normative data. All glucose tolerance groups showed appropriate and similar suppression of fasting glucagon. Four participants (17%) had mild hypoglycemic, three (13%) had moderate hypoglycemic, and eight (33%) had severe hypoglycemic. No participant with CFRD demonstrated hypoglycemic. Of the 19 participants without CFRD, 15 (79%) experienced hypoglycemic. Participants with hypoglycemic had greater peak glucose and insulin responses than those that did not have hypoglycemic, and this approached significance (p = .0625 for glucose and p = .0862 for insulin). No significant mean differences between GLP-1 and GIP release were found. There was no relationship between hypoglycemic and modulator therapy. CONCLUSION: Postprandial hypoglycemic was unmasked by the extension of an OGTT to 3 h. Delayed and abnormal insulin release, and ineffective counter-regulatory action of glucagon may have a role in its etiology.

In utero low-protein-diet-programmed type 2 diabetes in adult offspring is mediated by sex hormones in rats†.

Sex steroids regulate insulin sensitivity and glucose metabolism. We had characterized a lean type 2 diabetes (T2D) rat model using gestational low-protein (LP) diet programming. Our objective was to identify if endocrine dysfunction leading to decreased sex hormone levels will precede the development of T2D and if steroid replacement will prevent the onset of the disease. Pregnant rats were fed control or isocaloric LP diet from gestational day 4 until delivery. Normal diet was given to all mothers after delivery and to pups after weaning. LP offspring developed glucose intolerance and insulin resistance at 4 months. We measured sex steroid hormone profiles and expression of key genes involved in steroidogenesis in testis and ovary. Furthermore, one-month old rats were implanted with 90-day slow release T and E2 pellets for males and females, respectively. Glucose tolerance test (GTT) and euglycemic hyperinsulinemic clamp was performed at 4 months. LP-programmed T2D males had low T levels and females had low E2 levels due to dysregulated gene expression during steroidogenesis in gonads. GTT and euglycemic hyperinsulinemic clamp showed that LP males and females were glucose intolerant and insulin resistant; however, steroid supplementation prevented the onset of glucose intolerance and insulin resistance. Rats that developed T2D by LP programming have compromised gonadal steroidogenesis leading to low T and E2 in males and females, respectively. Sex steroid supplementation prevented the onset of glucose intolerance and insulin resistance indicating low sex steroid levels could cause compromised glucose metabolism ultimately leading to T2D.

Serum apelin and resistin levels in patients with impaired fasting glucose, impaired glucose tolerance, type 2 diabetes, and metabolic syndrome.

INTRODUCTION: The aim of this study was to investigate serum apelin and resistin levels in patients with impaired fasting glucose, impaired glucose tolerance, type 2 diabetes and metabolic syndrome. MATERIAL AND METHODS: The study comprised 18 patients with type 2 diabetes mellitus (T2DM) (nine females, nine males), 18 patients with impaired fasting glucose (IFG) (nine females, nine males), 18 patients with impaired glucose tolerance (IGT) (nine females, nine males), 18 patients with metabolic syndrome (MeS) (nine females, nine males), and 16 healthy individuals (eight females, eight males); serum adiponectin, apelin, resistin levels, fasting and postprandial blood glucose, insulin resistance markers, and lipid parameters were measured. RESULTS: In the study, serum apelin levels were determined to be significantly lower in IGT, MeS, and T2DM groups compared with the control group (p = 0.002, p = 0.006, and p < 0.001, respectively). Serum resistin levels were determined to be significantly higher in IGT and T2DM groups compared with the control group (p < 0.001 and p < 0.001, respectively). CONCLUSIONS: Apelin and resistin are thought to affect glucose metabolism and insulin resistance. Apelin is an important indicator in individuals with IGT in the prediabetic period and may play a role in preventing diabetic complications and treatment of T2DM.

High-refined carbohydrate diet leads to polycystic ovary syndrome-like features and reduced ovarian reserve in female rats.

Obesity is associated with several female reproductive complications, such as polycystic ovary syndrome (PCOS). The exact mechanism of this relationship remains unclear. Few previous studies using diet containing refined carbohydrate (HCD) leading to obesity have been performed and it is unclear if HCD is linked with reproductive dysfunctions. In this investigation, we assessed whether subchronic HCD exposure results in reproductive and other irregularities. Female rats were fed with HCD for 15 days and metabolic outcomes and reproductive tract morphophysiology were assessed. We further assessed reproductive tract inflammation, oxidative stress (OS) and fibrosis. HCD rats displayed metabolic impairments, such as an increase in body weight/adiposity, adipocyte hypertrophic, abnormal lipid profile, glucose tolerance and insulin resistance (IR) and hyperleptinemia. Improper functioning of the HCD reproductive tract was observed. Specifically, irregular estrous cyclicity, high LH levels and abnormal ovarian morphology coupled with reduction in primordial and primary follicle numbers was observed, suggesting ovarian reserve depletion. Improper follicular development and a reduction in antral follicles, corpora lutea and granulosa layer area together with an increase in cystic follicles were apparent. Uterine atrophy and reduction in endometrial gland (GE) number was observed in HCD rats. Reproductive tract inflammation, OS and fibrosis were seen in HCD rats. Further, strong positive correlations were observed between body weight/adiposity and IR with estrous cycle length, cystic follicles, ovarian reserve, GE and other abnormalities. Thus, these data suggest that the subchronic HCD exposure led to PCOS-like features, impaired ovarian reserve, GE number, and other reproductive abnormalities in female rats.

A Protein/Lipid Preload Attenuates Glucose-Induced Endothelial Dysfunction in Individuals with Abnormal Glucose Tolerance.

Postprandial hyperglycemia interferes with vascular reactivity and is a strong predictor of cardiovascular disease. Macronutrient preloads reduce postprandial hyperglycemia in subjects with impaired glucose tolerance (IGT) or type 2 diabetes (T2D), but the effect on endothelial function is unknown. Therefore, we examined whether a protein/lipid preload can attenuate postprandial endothelial dysfunction by lowering plasma glucose responses in subjects with IGT/T2D. Endothelial function was assessed by the reactive hyperemia index (RHI) at fasting, 60 min and 120 min during two 75 g oral glucose tolerance tests (OGTTs) preceded by either water or a macronutrient preload (i.e., egg and parmesan cheese) in 22 volunteers with IGT/T2D. Plasma glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), glucagon, free fatty acids, and amino acids were measured through each test. RHI negatively correlated with fasting plasma glucose. During the control OGTT, RHI decreased by 9% and its deterioration was associated with the rise in plasma glucose. The macronutrient preload attenuated the decline in RHI and markedly reduced postprandial glycemia. The beneficial effect of the macronutrient preload on RHI was proportional to the improvement in glucose tolerance and was associated with the increase in plasma GLP-1 and arginine levels. In conclusion, a protein/lipid macronutrient preload attenuates glucose-induced endothelial dysfunction in individuals with IGT/T2D by lowering plasma glucose excursions and by increasing GLP-1 and arginine levels, which are known regulators of the nitric oxide vasodilator system.