Peripheral Glucose Utilization Research Articles

In Silico Studies of (Z)-3-(2-Chloro-4-Nitrophenyl)-5-(4-Nitrobenzylidene)-2-Thioxothiazolidin-4-One Derivatives as PPAR-γ Agonist: Design, Molecular Docking, MM-GBSA Assay, Toxicity Predictions, DFT Calculations and MD Simulation Studies

Diabetes mellitus, a metabolic disorder, arises from insufficient insulin levels or increased insulin resistance. An alternative approach to address this pathogenesis involves targeting PPAR-[Formula: see text], which activates glucose homeostasis and improves peripheral glucose utilization. In this study, we aimed to investigate the designed 2-thioxothiazolidin-4-one derivatives (T1-25) and assess their potential as PPAR-[Formula: see text] regulators by an in silico approach. Physicochemical properties and Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) profiles were evaluated. Docking studies were performed using Schrödinger software, with the protein target being PPAR-[Formula: see text] (PDB ID: 2ZNO). Additionally, MD simulation studies were conducted, and the key interactions in the protein-ligand complexes were identified. The results demonstrate the drug-likeness of compounds T11, T24 and T25, with docking scores of –7.953 kcal/mol, –7.973 kcal/mol and –8.212 kcal/mol, respectively, and exhibit significant activity against PPAR-[Formula: see text] agonist and compared with the standard drug Pioglitazone (–7.367 kcal/mol). The density functional calculations were also performed to determine the geometrical properties, thermal parameters, chemical reactivity descriptors and molecular electrostatic potential of the compounds using the B3LYP functional and 6-31G++ basis sets. The energy difference between the highest occupied molecular orbitals and lowest unoccupied molecular orbitals for all the investigated compounds is in the range of 2.8–3.4 eV which allows for easy transfer of electrons and reactivity. Further research and development of these designed compounds could contribute to the advancement of effective antidiabetic treatments.

Repurposing Metformin for Vascular Disease.

Metformin has been used as an oral anti-hyperglycaemic drug since the late 1950s; however, following the release in 1998 of the findings of the 20-year United Kingdom Prospective Diabetes Study (UKPDS), metformin use rapidly increased and today is the first-choice anti-hyperglycaemic drug for patients with type 2 diabetes (T2D). Metformin is in daily use by an estimated 150 million people worldwide. Historically, the benefits of metformin as an anti-diabetic and cardiovascular-protective drug have been linked to effects in the liver, where it acts to inhibit gluconeogenesis and lipogenesis, as well as reduce insulin resistance and enhance peripheral glucose utilization. However, direct protective effects on the endothelium and effects in the gut prior to metformin absorption are now recognized as important. In the gut, metformin modulates the glucagon-like peptide- 1 (GLP-1) - gut-brain axis and impacts the intestinal microbiota. As the apparent number of putative tissue and cellular targets for metformin has increased, so has the interest in re-purposing metformin to treat other diseases that include polycystic ovary syndrome (PCOS), cancer, neurodegenerative diseases, and COVID-19. Metformin is also being investigated as an anti-ageing drug. Of particular interest is whether metformin provides the same level of vascular protection in individuals other than those with T2D, including obese individuals with metabolic syndrome, or in the setting of vascular thromboinflammation caused by SARS-CoV-2. In this review, we critically evaluate the literature to highlight clinical settings in which metformin might be therapeutically repurposed for the prevention and treatment of vascular disease.

Short-term fasting lowers glucagon levels under euglycemic and hypoglycemic conditions in healthy humans.

Fasting is associated with increased susceptibility to hypoglycemia in people with type 1 diabetes, thereby making it a significant health risk. To date, the relationship between fasting and insulin-induced hypoglycemia has not been well characterized, so our objective was to determine whether insulin-independent factors, such as counterregulatory hormone responses, are adversely impacted by fasting in healthy control individuals. Counterregulatory responses to insulin-induced hypoglycemia were measured in 12 healthy people during 2 metabolic studies. During one study, participants ate breakfast and lunch, after which they underwent a 2-hour bout of insulin-induced hypoglycemia (FED). During the other study, participants remained fasted prior to hypoglycemia (FAST). As expected, hepatic glycogen concentrations were lower in FAST, and associated with diminished peak glucagon levels and reduced endogenous glucose production (EGP) during hypoglycemia. Accompanying lower EGP in FAST was a reduction in peripheral glucose utilization, and a resultant reduction in the amount of exogenous glucose required to maintain glycemia. These data suggest that whereas a fasting-induced lowering of glucose utilization could potentially delay the onset of insulin-induced hypoglycemia, subsequent reductions in glucagon levels and EGP are likely to encumber recovery from it. As a result of this diminished metabolic flexibility in response to fasting, susceptibility to hypoglycemia could be enhanced in patients with type 1 diabetes under similar conditions.

1576-P: Hepatic Ketogenesis Insufficiency Improves Glycemia in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease and is increasing by approximately 2-3% per year. One characteristic feature of T1D is the increased production of ketone bodies. However, the role of ketone bodies and/or ketogenesis in the pathogenesis of T1D remains unknown. We generated mice with conditional ketogenic insufficiency by knocking out the ketogenic enzyme 3-hydroxy methylglutaryl CoA synthase 2 (Hmgcs2) in the liver. Six to eight-week-old Hmgcs2ΔLiv and Hmgcs2F/F(littermates that do not express Alb-Cre) were injected with tamoxifen @200 mg/kg body weight. One week later, Hmgcs2ΔLiv and Hmgcs2F/F mice were injected with strep tozotocin (STZ; 50mg/kg B.W for 5 consecutive days) to induce hyperglycemia. We found that Hmgcs2ΔLiv mice had significantly lower blood glucose than their littermate controls. The improvement in glycemia is not due to a change in food intake or body weight. Moreover, no difference in serum insulin levels and Akt phosphorylation in the liver suggested that ketogenic insufficiency does not improve glycemia in T1D via the insulin signaling pathway. When we assessed glucose production by pyruvate tolerance test, Hmgcs2ΔLiv mice showed lower glucose levels. Further, the mRNA and protein levels of gluconeogenic genes such as G6PCand PCK1 were significantly decreased in the livers of Hmgcs2ΔLivmice. We also observed a significant reduction in PGC-1α, the transcriptional regulator of gluconeogenesis, suggesting that ketogenic insufficiency in T1D reduces hepatic gluconeogenesis. The metabolism of ketone bodies in peripheral tissues impairs their ability to utilize glucose. Our indirect calorimetry analysis showed a trend toward increased respiratory exchange ratio (RER) in STZ-treated Hmgcs2ΔLiv mice, suggesting that ketogenic insufficiency increases carbohydrate metabolism in T1D. Our data show that ketogenesis may contribute to hyperglycemia in T1D by regulating hepatic glucose production and peripheral glucose utilization. Disclosure R.Mooli: None. S.Ramakrishnan: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (DK110537)

Automated Insulin Delivery for Hypoglycemia Avoidance and Glucose Counterregulation in Long-Standing Type 1 Diabetes with Hypoglycemia Unawareness.

Objective: Automated insulin delivery (AID) may benefit individuals with long-standing type 1 diabetes where frequent exposure to hypoglycemia impairs counterregulatory responses. This study assessed the effect of 18 months AID on hypoglycemia avoidance and glucose counterregulatory responses to insulin-induced hypoglycemia in long-standing type 1 diabetes complicated by impaired awareness of hypoglycemia. Methods: Ten participants mean ± standard deviation age 49 ± 16 and diabetes duration 34 ± 16 years were initiated on AID. Continuous glucose monitoring was paired with actigraphy to assess awake- and sleep-associated hypoglycemia exposure every 3 months. Hyperinsulinemic hypoglycemic clamp experiments were performed at baseline, 6, and 18 months postintervention. Hypoglycemia exposure was reduced by 3 months, especially during sleep, with effects sustained through 18 months (P ≤ 0.001) together with reduced glucose variability (P < 0.01). Results: Hypoglycemia awareness and severity scores improved (P < 0.01) with severe hypoglycemia events reduced from median (interquartile range) 3 (3-10) at baseline to 0 (0-1) events/person·year postintervention (P = 0.005). During the hypoglycemic clamp experiments, no change was seen in the endogenous glucose production (EGP) response, however, peripheral glucose utilization during hypoglycemia was reduced following intervention [pre: 4.6 ± 0.4, 6 months: 3.8 ± 0.5, 18 months: 3.4 ± 0.3 mg/(kg·min), P < 0.05]. There were increases over time in pancreatic polypeptide (Pre:62 ± 29, 6 months:127 ± 44, 18 months:176 ± 58 pmol/L, P < 0.01), epinephrine (Pre: 199 ± 53, 6 months: 332 ± 91, 18 months: 386 ± 95 pg/mL, P = 0.001), and autonomic symptom (Pre: 6 ± 2, 6 months: 6 ± 2, 18 months: 10 ± 2, P < 0.05) responses. Conclusions: AID led to a sustained reduction of hypoglycemia exposure. EGP in response to insulin-induced hypoglycemia remained defective, however, partial recovery of glucose counterregulation was evidenced by a reduction in peripheral glucose utilization likely mediated by increased epinephrine secretion and, together with improved autonomic symptoms, may contribute to the observed clinical reduction in hypoglycemia.

Management of Diabetes Mellitus, Risk Factors and Complications

Chronic progressive metabolic problem and chronic hyperglycemia caused by a dysregulation of protein, lipid, and carbohydrate metabolism are two symptoms of diabetes mellitus, a complicated condition. Verapamil belongs to a group of calcium channel blockers that are not dihydropyridines. It works by preventing calcium from entering beta cells' cytoplasm, preventing the second phase of insulin release driven by glucose, as well as sulfonylurea and glucagon. Nephropathy, neuropathy, and retinopathy are examples of microvascular consequences of diabetes mellitus (cardiovascular and cerebrovascular disease). In both kinds of diabetes mellitus, higher urine albumin excretion (proteinuria) or decreased kidney glomerular filtration rate are symptoms of diabetic nephropathy, a microvascular consequence. By lowering patients' blood sugar levels and reducing their risk of cardiovascular disease, diabetes mellitus therapy aims to reduce mortality, delay the onset of disease complications, and slow the disease's progression. Metformin increases peripheral glucose utilization, liver, muscle, and adipose tissue sensitivity to insulin, inhibits gluconeogenesis, and reduces glucose absorption from the gastrointestinal system.

RF04 | PSUN297 Genetic Knockout of Intestinal Hexokinase Domain Containing Protein-1 Affects Enterocyte Glucose Transport in Mice Fed High Fat Diet

Abstract Hexokinase domain containing protein-1, or HKDC1, is a widely expressed novel hexokinase that is genetically associated with elevated 2-hour gestational blood glucose levels during an oral glucose tolerance test, suggesting a role for HKDC1 in postprandial glucose regulation during pregnancy. Our earlier studies utilizing transgenic mice containing whole-body HKDC1 knockdown, or mice in which hepatic HKDC1 was overexpressed or knocked out, indicated that HKDC1 is important for whole-body glucose homeostasis in aging and pregnancy, through modulation of glucose tolerance, peripheral tissue glucose utilization, and hepatic energy storage. However, our knowledge of the precise mechanisms by which HKDC1 regulates postprandial glucose homeostasis under normal and diabetic conditions is lacking. As the intestine is the main entry portal for dietary glucose, and since HKDC1 is highly expressed within the intestine, in this study we assessed and characterized the in vivo significance of intestine-specific HKDC1 in regulating glucose homeostasis under normal and obesogenic conditions. We developed an intestine-specific HKDC1 knockout mouse model, HKDC1Int-/-, utilizing Cre-mediated recombination of HKDC1 in which Cre was expressed under the control of the villin gene promoter, leading to genetic knockout of HKDC1 solely within the intestinal epithelium. Mice were maintained until 28 weeks of age on either a normal chow diet or a high fat diet to develop obesity, hyperglycemia, and insulin resistance. While no overt glycemic phenotype was observed, 28-week-old HKDC1Int-/- mice fed a high fat diet exhibited an increased glucose excursion following an oral glucose load compared to mice expressing intestinal HKDC1. This finding was not due to differences in insulin levels, whole-body insulin tolerance, or gluconeogenesis, nor was it a result of alterations in enterocyte glucose utilization or a reduction in peripheral skeletal muscle glucose uptake. Furthermore, the enhanced glucose excursion was related to transport of glucose through the intestinal epithelium, as mice administered an intraperitoneal glucose load did not exhibit alterations in post-load glycemic excursion. Assessment of intestinal glucose transporters in high fat diet-fed HKDC1Int-/- mice indicated an increased expression of GLUT2 in the enterocyte apical membrane in the fasting state. Taken together, our results indicate that intestine-specific HKDC1 contributes to postprandial glycemic regulation by modulating dietary glucose transport across the intestinal epithelium under conditions of enhanced metabolic stress, such as obesity, hyperglycemia, and diabetes. Presentation: Saturday, June 11, 2022 1:24 p.m. - 1:29 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

PSAT089 Lack of Effect of Metformin in Murine Pheochromocytoma Model

Abstract Metformin, a lipophilic biguanide inhibiting hepatic gluconeogenesis and improving peripheral utilization of glucose, is a well-established medication for the management of type 2 diabetes. Furthermore, metformin has been shown to have pleiotropic effects targeting oxidative phosphorylation via complex I inhibition. Thus, it regulates the energy supply to cells from mitochondrial complex I respiration along with reduced glycolytic metabolism. Several pre-clinical in vitro studies on cell lines derived from pheochromocytoma (PHEO) have suggested anti-proliferative potential of metformin which hints that metformin could be used as a potent candidate for PHEO anti-cancer therapy. However, these results have yet to be confirmed in vivo. Murine PHEO MPC cells and human progenitor hPheo1 cells were treated with metformin in vitro to study the effect on cell proliferation and ATP production. Mice were injected with MTT cells subcutaneously and when the tumors reached the average volume of 120.2±48.1 mm3, they were randomized into 3 groups (n=5) treated with vehicle, 125 mg/kg metformin i.p. daily (6 times a week), or the drug dissolved into drinking water (5 mg/ml). Tumor progression and survival data were collected. Metformin effectively decreased PHEO cell proliferation and overall ATP production in dose-dependent manner in vitro. Tumor progression was similar in both metformin-treated groups and control group with no significant effect on the growth or mice survival. Even though the metformin showed antiproliferative effects in both murine and human derived cells in vitro, we did not observe tumor growth limitation in our model of murine pheochromocytoma in vivo. However, further studies including newer models and variable treatment conditions including timing, are needed to clarify the lack of efficacy in vivo. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

The Potential Therapeutic Role of Metformin in Diabetic and Non-Diabetic Bone Impairment.

Metformin is a widely-used anti-diabetic drug in patients with type 2 diabetic mellitus (T2DM) due to its safety and efficacy in clinical. The classic effect of metformin on lowering blood glucose levels is to inhibit liver gluconeogenesis that reduces glucose production as well as increases peripheral glucose utilization. However, the factors such as hyperglycemia, insulin deficiency, reduced serum levels of insulin-like growth factor-1 (IGF-1) and osteocalcin, accumulation of advanced glycation end products (AGEs), especially in collagen, microangiopathy, and inflammation reduced bone quality in diabetic patients. However, hyperglycemia, insulin deficiency, reduced levels of insulin-like growth factor-1 (IGF-1) and osteocalcin in serum, accumulation of advanced glycation end products (AGEs) in collagen, microangiopathy, and inflammation, reduce bone quality in diabetic patients. Furthermore, the imbalance of AGE/RAGE results in bone fragility via attenuating osteogenesis. Thus, adequate glycemic control by medical intervention is necessary to prevent bone tissue alterations in diabetic patients. Metformin mainly activates adenosine 5′ -monophosphate-activated protein kinase (AMPK), and inhibits mitochondrial respiratory chain complex I in bone metabolism. In addition, metformin increases the expression of transcription factor runt-related transcription factor2 (RUNX2) and Sirtuin protein to regulate related gene expression in bone formation. Until now, there are a lot of preclinical or clinical findings on the application of metformin to promote bone repair. Taken together, metformin is considered as a potential medication for adjuvant therapy in bone metabolic disorders further to its antidiabetic effect. Taken together, as a conventional hypoglycemia drug with multifaceted effects, metformin has been considered a potential adjuvant drug for the treatment of bone metabolic disorders.

Role of metformin in prevention and prognosis of breast cancer

Dear Editor, Metformin is a hypoglycemic drug of the class biguanides used as the first-line treatment for type 2 diabetes mellitus (T2DM). The drug acts by inhibiting hepatic gluconeogenesis, decreasing intestinal absorption of glucose and circulating insulin. It has also been suggested that the drug indirectly increases insulin sensitivity by increasing peripheral glucose utilization. Data from the World Health Organization (WHO) shows that breast cancer (BC) is the most prevalent cancer in women, with an incidence of 1.7 million cases in 2012 (25 % of all female cancers). It is the fifth leading cause of death from cancer overall.1 A clinical trial conducted in 2019 elaborated that metformin altered host metabolism proving to be a substitute for a fasting-like mechanism that affects cancer cells' metabolism and growth environment of cancer cells including an increase in beta-OH-butyric acid (BHBA).2 It was further corroborated by a research that found an inverse relationship between metformin and BC. This is accomplished by boosting the activity of AMP-dependent protein kinase, which suppresses the mTOR-associated oncogenic signalling pathway. This induces S phase arrest and apoptosis in triple-negative breast cancer cells. Data from 18,527 participants brought about 2,680 participants who used metformin at least three months before the diagnosis of BC. A multivariate study showed that this was negatively associated with BC risk (0.821, 0.726-0.912, p=0.002).3 A favourable response on disease-free survival and overall survival in BC patients with T2DM. The number of CD8+ tumour-infiltrating lymphocytes (TILS) has been increased with the use of metformin engendering anti-carcinogenic effects.4 In the last 15 years, we have seen a drastic change in the demographics of BC, with an estimated increase of 70.7 to 130.6% in 2020 and 2025 relative to 2015 in the 30-34 age group in Pakistan.5 There has been a significant increase in T2DM along with increased use of metformin for its treatment which thus raises a question about the efficacy of the drug in a neoadjuvant setting for BC on Pakistani society. Further research, especially clinical trials, needs to be conducted in Pakistan including but not limited to a correlation of metformin use and incidence of BC.

Risk Factors, Complications and Management of Diabetes Mellitus

Diabetes mellitus can be a complex disorder described by chronic progressive metabolic disorder and chronic hyperglycemia arising from dysregulation of carbohydrate, lipid and protein metabolism. Verapamil is a class of non-dihydropyridine calcium channel blockers, which prevents the second phase of glucose stimulated insulin release by inhibiting the intake of calcium into the cytosol of beta cells and also prevents sulfonylurea and glucagon-induced insulin release. The complications of diabetes mellitus are categorized as microvascular (nephropathy, neuropathy, and retinopathy) or macrovascular (cardiovascular and cerebrovascular disease). Diabetic nephropathy is a microvascular complication described by elevated urinary albumin excretion (proteinuria) or lowered kidney glomerular filtration rate in both types of diabetic mellitus. The objective of diabetes mellitus management is to inhibit the mortality and to delay the onset of disease complications and to hinder its progression by improving patients’ blood sugar level and controlling the risk of cardiovascular disease. Metformin enhances liver, muscle & adipose tissues sensitivity to the insulin and elevate peripheral glucose utilization and also prevents gluconeogenesis and obviates glucose absorption from gastrointestinal tract.

Cyclooxygenase-2 in adipose tissue macrophages limits adipose tissue dysfunction in obese mice.

Obesity-associated complications are causing increasing morbidity and mortality worldwide. Expansion of adipose tissue in obesity leads to a state of low-grade chronic inflammation and dysregulated metabolism, resulting in insulin resistance and metabolic syndrome. Adipose tissue macrophages (ATMs) accumulate in obesity and are a source of proinflammatory cytokines that further aggravate adipocyte dysfunction. Macrophages are rich sources of cyclooxygenase (COX), the rate limiting enzyme for prostaglandin E2 (PGE2) production. When mice were fed a high-fat diet (HFD), ATMs increased expression of COX-2. Selective myeloid cell COX-2 deletion resulted in increased monocyte recruitment and proliferation of ATMs, leading to increased proinflammatory ATMs with decreased phagocytic ability. There were increased weight gain and adiposity, decreased peripheral insulin sensitivity and glucose utilization, increased adipose tissue inflammation and fibrosis, and abnormal adipose tissue angiogenesis. HFD pair-feeding led to similar increases in body weight, but mice with selective myeloid cell COX-2 still exhibited decreased peripheral insulin sensitivity and glucose utilization. Selective myeloid deletion of the macrophage PGE2 receptor subtype, EP4, produced a similar phenotype, and a selective EP4 agonist ameliorated the metabolic abnormalities seen with ATM COX-2 deletion. Therefore, these studies demonstrated that an ATM COX-2/PGE2/EP4 axis plays an important role in inhibiting adipose tissue dysfunction.

Enterocyte HKDC1 Modulates Intestinal Glucose Absorption in Male Mice Fed a High-fat Diet.

Hexokinase domain containing protein-1, or HKDC1, is a widely expressed hexokinase that is genetically associated with elevated 2-hour gestational blood glucose levels during an oral glucose tolerance test, suggesting a role for HKDC1 in postprandial glucose regulation during pregnancy. Our earlier studies utilizing mice containing global HKDC1 knockdown, as well as hepatic HKDC1 overexpression and knockout, indicated that HKDC1 is important for whole-body glucose homeostasis in aging and pregnancy, through modulation of glucose tolerance, peripheral tissue glucose utilization, and hepatic energy storage. However, our knowledge of the precise role(s) of HKDC1 in regulating postprandial glucose homeostasis under normal and diabetic conditions is lacking. Since the intestine is the main entry portal for dietary glucose, here we have developed an intestine-specific HKDC1 knockout mouse model, HKDC1Int–/–, to determine the in vivo role of intestinal HKDC1 in regulating glucose homeostasis. While no overt glycemic phenotype was observed, aged HKDC1Int–/– mice fed a high-fat diet exhibited an increased glucose excursion following an oral glucose load compared with mice expressing intestinal HKDC1. This finding resulted from glucose entry via the intestinal epithelium and is not due to differences in insulin levels, enterocyte glucose utilization, or reduction in peripheral skeletal muscle glucose uptake. Assessment of intestinal glucose transporters in high-fat diet–fed HKDC1Int–/– mice suggested increased apical GLUT2 expression in the fasting state. Taken together, our results indicate that intestinal HKDC1 contributes to the modulation of postprandial dietary glucose transport across the intestinal epithelium under conditions of enhanced metabolic stress, such as high-fat diet.

Evaluation of Lipid Profile and Fasting Blood Glucose Among Pregnant Women at Omdurman Maternity Hospital

Background: During pregnancy, maternal metabolic environment is modified by a rise in serum levels of estrogen and progesterone, pancreatic beta-cell hyperplasia and an increase in the secretion of insulin. Hyperinsulinemia leads to an increase in peripheral glucose utilization, a decline in fasting plasma glucose levels, increased tissue storage of glycogen, increased storage of fats and decreased lipolysis. The aim of our current study to investigate the changes in lipid profile, blood glucose and blood pressure throughout three trimesters in pregnant ladies. Materials and Methods: This is a hospital based, descriptive analytical cross-sectional study, performed at refer clinic of Omdurman Maternity hospital in Khartoum state. Included 150 apparently healthy pregnant ladies in the study group and 40 healthy non-pregnant ladies as a control group. Anthropometric measurements and blood pressure were measured and blood sample was obtained to analyzed lipid profile and blood glucose. Results: Data analysis showed that the mean level of triglyceride tend to change from slight increase in first trimester and significant increase in the second and third trimester. While mean level of HDL tend to change from slight decrease in the first and second trimester to significant decrease in the third trimester. Whereas there was an increase in both total cholesterol and LDL but was not significant. The mean level of fasting blood glucose was significantly raised in third trimester compared to other first and second Trimesters. Both component of blood pressure was significantly elevated in the first and third trimesters compare to second trimester. Conclusion: Normal pregnancy is associated with dyslipidemic changes due to elevated pregnancy related hormones. Increased insulin resistance leads to production of dyslipidemic changes in mother in form of elevated TG, total cholesterol, LDL and decreased HDL in serum and increased random blood glucose.

Metformin and Insulin Resistance: A Review of the Underlying Mechanisms behind Changes in GLUT4-Mediated Glucose Transport.

Metformin is the most commonly used treatment to increase insulin sensitivity in insulin-resistant (IR) conditions such as diabetes, prediabetes, polycystic ovary syndrome, and obesity. There is a well-documented correlation between glucose transporter 4 (GLUT4) expression and the level of IR. Therefore, the observed increase in peripheral glucose utilization after metformin treatment most likely comes from the induction of GLUT4 expression and its increased translocation to the plasma membrane. However, the mechanisms behind this effect and the critical metformin targets are still largely undefined. The present review explores the evidence for the crucial role of changes in the expression and activation of insulin signaling pathway mediators, AMPK, several GLUT4 translocation mediators, and the effect of posttranscriptional modifications based on previously published preclinical and clinical models of metformin’s mode of action in animal and human studies. Our aim is to provide a comprehensive review of the studies in this field in order to shed some light on the complex interactions between metformin action, GLUT4 expression, GLUT4 translocation, and the observed increase in peripheral insulin sensitivity.

Pharmacogenetics of Metformin

Hyperglycemia is a medical condition in which an increase in glucose levels in the blood exceeds normal limits. Hyperglycemia is one of the typical signs of diabetes mellitus (DM). The World Health Organization (WHO) predicts an increase in the number of people with DM which is a global health threat. Diabetes is the leading cause of kidney failure, and the leading cause of heart disease and stroke, in adults. Metformin, which is a biguanide group, is recommended by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes as the first-line oral therapy for DM and is the most widely used oral medication worldwide. Metformin can also increase peripheral glucose utilization and ultimately decrease the production of fatty acids and triglycerides. Some of the individual differences that underlie the variation in response to metformin.

Pharmacogenetics of Metformin

Hyperglycemia is a medical condition in which an increase in glucose levels in the blood exceeds normal limits. Hyperglycemia is one of the typical signs of diabetes mellitus (DM). The World Health Organization (WHO) predicts an increase in the number of people with DM which is a global health threat. Diabetes is the leading cause of kidney failure, and the leading cause of heart disease and stroke, in adults. Metformin, which is a biguanide group, is recommended by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes as the first-line oral therapy for DM and is the most widely used oral medication worldwide. Metformin can also increase peripheral glucose utilization and ultimately decrease the production of fatty acids and triglycerides. Some of the individual differences that underlie the variation in response to metformin.

Nmp4, a Regulator of Induced Osteoanabolism, Also Influences Insulin Secretion and Sensitivity.

A bidirectional and complex relationship exists between bone and glycemia. Persons with type 2 diabetes (T2D) are at risk for bone loss and fracture, however, heightened osteoanabolism may ameliorate T2D-induced deficits in glycemia as bone-forming osteoblasts contribute to energy metabolism via increased glucose uptake and cellular glycolysis. Mice globally lacking nuclear matrix protein 4 (Nmp4), a transcription factor expressed in all tissues and conserved between humans and rodents, are healthy and exhibit enhanced bone formation in response to anabolic osteoporosis therapies. To test whether loss of Nmp4 similarly impacted bone deficits caused by diet-induced obesity, male wild-type and Nmp4-/- mice (8weeks) were fed either low-fat diet or high-fat diet (HFD) for 12weeks. Endpoint parameters included bone architecture, structural and estimated tissue-level mechanical properties, body weight/composition, glucose-stimulated insulin secretion, glucose tolerance, insulin tolerance, and metabolic cage analysis. HFD diminished bone architecture and ultimate force and stiffness equally in both genotypes. Unexpectedly, the Nmp4-/- mice exhibited deficits in pancreatic β-cell function and were modestly glucose intolerant under normal diet conditions. Despite the β-cell deficits, the Nmp4-/- mice were less sensitive to HFD-induced weight gain, increases in % fat mass, and decreases in glucose tolerance and insulin sensitivity. We conclude that Nmp4 supports pancreatic β-cell function but suppresses peripheral glucose utilization, perhaps contributing to its suppression of induced skeletal anabolism. Selective disruption of Nmp4 in peripheral tissues may provide a strategy for improving both induced osteoanabolism and energy metabolism in comorbid patients.

113-LB: The Role of “Osmotoxicity” in Type 2 Diabetes Mellitus: A Retrospective Comparative Analysis of the Effect of Pretreatment with IV 0.9% Saline on Glycemic Control in Subcritical Hyperglycemia

Background: Experimental studies have shown that an increase in serum osmolality (Osm) of even 10 mOsm/kg significantly contributes to progressive hyperglycemia by increasing hepatic glucose output and suppressing peripheral glucose utilization. The Osm increases parallel to the increase in blood glucose (BG) and vice versa. This is not therapeutically exploited yet. Aim: To assess the effect of pre-treatment with IV 0.9% saline (NS) on glycemic control and medication requirement in type 2 diabetes mellitus (T2DM) patients presenting with subcritical hyperglycemia (SCH) -hyperglycemia not amounting to DKA or HHS. Method: A retrospective comparative data analysis of T2DM patients (198) with SCH, pre-treated with NS before diabetic specific therapy (group 1) and compared with those who were not pre-treated with NS (group 2). Differences in glycemic control and drug dosage were assessed. Results: In group 1, 1500ml of NS administration reduced the BG from a baseline of 496.3±67.1 to 283.3±83.8 (mg/dL), p=0.000 with a mean reduction of 43% and reduced the Osm by 11mOsm/kg [313.8±8.1 to 302.9±8.5, p&amp;lt;0.001]. There was a significant correlation between BG and Osm (r=0.322, p=0.001). Fluid pre-treatment enabled a better reduction in BG during 4 weeks of follow up in group 1{[FBS- 298.9±73.7 to 158.9±58.7 in group 1 v/s 265.6±70.7 to 171.48±66.5 in group 2, p=0.00] and [RBS- 496.3±67.1 to 228.3±80.7 in group 1 v/s 450.5±47 to 282±112.4 in group 2, p=0.001]}. There was a general trend of decrease in the dosages of antidiabetic medications in group 1 and increase of the same in group 2. Conclusions: IV fluid pre-treatment reduced the BG and the drug dosage in T2DM patients presenting with SCH and the benefit persisted for a minimum of 4 weeks. Disclosure P. Sureshkumar: None.

FoxO1 suppresses Fgf21 during hepatic insulin resistance to impair peripheral glucose utilization and acute cold tolerance

SUMMARYFgf21 (fibroblast growth factor 21) is a regulatory hepatokine that, in pharmacologic form, powerfully promotes weight loss and glucose homeostasis. Although “Fgf21 resistance” is inferred from higher plasma Fgf21 levels in insulin-resistant mice and humans, diminished Fgf21 function is understood primarily via Fgf21 knockout mice. By contrast, we show that modestly reduced Fgf21—owing to cell-autonomous suppression by hepatic FoxO1—contributes to dysregulated metabolism in LDKO mice (Irs1L/L·Irs2L/L·CreAlb), a model of severe hepatic insulin resistance caused by deletion of hepatic Irs1 (insulin receptor substrate 1) and Irs2. Knockout of hepatic Foxo1 in LDKO mice or direct restoration of Fgf21 by adenoviral infection restored glucose utilization by BAT (brown adipose tissue) and skeletal muscle, normalized thermogenic gene expression in LDKO BAT, and corrected acute cold intolerance of LDKO mice. These studies highlight the Fgf21-dependent plasticity and importance of BAT function to metabolic health during hepatic insulin resistance.