The effect of insulin treatment on insulin secretion and insulin action in type II diabetes mellitus

Real-world effectiveness of early insulin therapy on the incidence of cardiovascular events in newly diagnosed type 2 diabetes

Early insulin therapy is capable to achieve glycemic control and restore β-cell function in newly diagnosed type 2 diabetes (T2D), but its effect on cardiovascular outcomes in these patients remains unclear. In this nationwide real-world study, we analyzed electronic health record data from 19 medical centers across China between 1 January 2000, and 26 May 2022. We included 5424 eligible patients (mean age 56 years, 2176 women/3248 men) who were diagnosed T2D within six months and did not have prior cardiovascular disease. Multivariable Cox regression models were used to estimate the associations of early insulin therapy (defined as the first-line therapy for at least two weeks in newly diagnosed T2D patients) with the incidence of major cardiovascular events including coronary heart disease (CHD), stroke, and hospitalization for heart failure (HF). During 17,158 persons years of observation, we documented 834 incident CHD cases, 719 stroke cases, and 230 hospitalized cases for HF. Newly diagnosed T2D patients who received early insulin therapy, compared with those who did not receive such treatment, had 31% lower risk of incident stroke, and 28% lower risk of hospitalization for HF. No significant difference in the risk of CHD was observed. We found similar results when repeating the aforesaid analysis in a propensity-score matched population of 4578 patients and with inverse probability of treatment weighting models. These findings suggest that early insulin therapy in newly diagnosed T2D may have cardiovascular benefits by reducing the risk of incident stroke and hospitalization for HF.

Exogenous Insulin Therapy Is Associated with the Risk of Advanced Colorectal Adenoma in Patients with Diabetes Mellitus

BACKGROUND/AIMS

Exogenous insulin therapy increases systemic exposure to insulin which may promote the development of colorectal neoplasia. We sought to evaluate the association between exogenous insulin therapy and the incidence of advanced adenoma in type 2 diabetes mellitus.

METHODS

A retrospective cohort study was conducted from January 1, 2007, to January 1, 2018, in a regional health system serving the United States Philadelphia metropolitan area, Central New Jersey, and South Central Pennsylvania. Study patients consisted of a random sample of patients with type 2 diabetes mellitus aged 40-80 years who had undergone two rounds of colonoscopy examinations. The exposure was cumulative duration of insulin therapy (i.e., no use, 1-365 days and > 365 days). The outcome was time to incident advanced adenoma.

RESULTS

Of the 975 eligible patients, 184 patients accumulated > 365 days of insulin therapy before the follow-up colonoscopy. The mean (standard deviation) duration between the two rounds of colonoscopy examination was 5.1 (2.9) years among the insulin users and 5.3 (3.9) years among non-users. Compared to no insulin exposure, receiving > 365 days of insulin therapy was associated with an increased incidence of advanced adenoma (adjusted hazard ratio [aHR] 4.84, 95% confidence interval [CI] 2.82-8.30), right-sided advanced adenoma (aHR 5.48, 95% CI 2.90-10.35), and 3 or more adenomas (aHR 2.61, 95% CI 1.46-4.69) at the follow-up colonoscopy examination.

CONCLUSION

Insulin therapy is associated with an increased risk of advanced adenoma and may serve as a novel risk-stratification factor to enhance the efficiency of existing colorectal cancer screening and surveillance programs.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Sustained hyperglycemia specifically targets translation of mRNAs for insulin secretion

Pancreatic β cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair β cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion is similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on β cell mRNA translation. Before induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our study uncovered a translational regulatory circuit during β cell glucose toxicity that impairs expression of proteins with critical roles in β cell function.

Beta-cell function in type 2 diabetes (T2DM): Can it be preserved or enhanced?

Type 2 diabetes (T2DM) is a complex metabolic disorder manifested by hyperglycemia, insulin resistance, and deteriorating beta-cell function. A way to prevent progression of the disease might be to enhance beta-cell function and insulin secretion. However, most previous studies examined beta-cell function while patients were using glycemia-lowering agents without an adequate period off medications (washout). In the present review we focus on studies with a washout period. We performed a literature search (2010 to June 2021) using beta-cell function and enhancement. The evidence shows that beta-cell function can be enhanced. Bariatric surgery and very low calorie diets show improvement in beta-cell function in many individuals. In addition, use of glucagon-like peptide-1 receptor agonists for prolonged periods (3 years or more) can also lead to improvement of beta-cell function. Further research is needed to understand the mechanisms leading to improved beta-cell function and identify agents that could enhance beta-cell function in patients with T2DM.

Sustained hyperglycemia specifically targets translation of mRNAs for insulin secretion

Pancreatic β-cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair β-cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion are similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on β-cell mRNA translation. Prior to induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also of mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex-vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our findings uncover a translational regulatory circuit during β-cell glucose toxicity that impairs expression of proteins with critical roles in β-cell function.

Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes?

Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.

Incretin and Pancreatic β-Cell Function in Patients with Type 2 Diabetes

To maintain normal glucose homeostasis after a meal, it is essential to secrete an adequate amount of insulin from pancreatic β-cells. However, if pancreatic β-cells solely depended on the blood glucose level for insulin secretion, a surge in blood glucose levels would be inevitable after the ingestion of a large amount of carbohydrates. To avoid a deluge of glucose in the bloodstream after a large carbohydrate- rich meal, enteroendocrine cells detect the amount of nutrient absorption from the gut lumen and secrete incretin hormones at scale. Since insulin secretion in response to incretin hormones occurs only in a hyperglycemic milieu, pancreatic β-cells can secrete a "Goldilocks" amount of insulin (i.e., not too much and not too little) to keep the blood glucose level in the normal range. In this regard, pancreatic β-cell sensitivity to glucose and incretin hormones is crucial for maintaining normal glucose homeostasis. In this Namgok lecture 2022, we review the effects of current anti-diabetic medications on pancreatic β-cell sensitivity to glucose and incretin hormones.

The Common Single Cause of Chronic Multi-Hormonal Resistance in Oxidative Stress

In diseases with concomitant oxidative stress, chronic multi-hormonal resistances could be detected. The most conspicuous component of these resistances is insulin resistance, but also leptin, erythropoietin, acetylcholine, triiodothyronine and glucagon-like peptide-1 resistances also occur. On the other hand, in oxidative stress, abnormal tyrosines, for instance, meta- and ortho-tyrosine are also produced and incorporated into the proteins through the translational process. In case these modified proteins are components of the intracellular signalling pathways, a hormonal resistance may develop. The above-mentioned hormones, owning overlapping signalling pathways at the insulin receptor substrate, develop an abnormal tyrosine phosphorylation dependent chronic multi-hormonal resistance. A few weeks free of oxidative stress or the use of antioxidant therapy are required to provide a return from this resistance, which return may be further supported by the supplementation of physiological para-tyrosine and by the add-on therapy of a pharmacological dose of glucagon-like peptide-1 receptor agonist, which is able to bypass the critical insulin receptor substrate signalling.

Multi-Level High-Throughput Screening for Discovery of Ligands That Inhibit Insulin Aggregation

We have developed a multi-level virtual screening protocol to identify lead molecules from the FDA inactives database that can inhibit insulin aggregation. The method is based on the presence of structural and interaction specificity in non-native aggregation pathway protein-protein interactions. Some key challenges specific to the present problem, when compared with native protein association, include structural heterogeneity of the protein species involved, multiple association pathways, and relatively higher probability of conformational rearrangement of the association complex. In this multi-step method, the inactives database was first screened using the dominant pharmacophore features of previously identified molecules shown to significantly inhibit insulin aggregation nucleation by binding to its aggregation-prone conformers. We then performed ensemble docking of several low-energy ligand conformations on these aggregation-prone conformers followed by molecular dynamics simulations and binding affinity calculations on a subset of docked complexes to identify a final set of five potential lead molecules to inhibit insulin aggregation nucleation. Their effect on aggregation inhibition was extensively investigated by incubating insulin under aggregation-prone aqueous buffer conditions (low pH, high temperature). Aggregation kinetics were characterized using size exclusion chromatography and Thioflavin T fluorescence assay, and the secondary structure was determined using circular dichroism spectroscopy. Riboflavin provided the best aggregation inhibition, with 85% native monomer retention after 48 h incubation under aggregation-prone conditions, whereas the no-ligand formulation showed complete monomer loss after 36 h. Further, insulin incubated with two of the screened inactives (aspartame, riboflavin) had the characteristic α-helical dip in CD spectra, while the no-ligand formulation showed a change to β-sheet rich conformations.

Effects of Sustained Hyperglycemia on Skeletal Muscle Lipids in Healthy Subjects

CONTEXT

Sustained increases in plasma glucose promote skeletal muscle insulin resistance independent from obesity and dyslipidemia (ie, glucotoxicity). Skeletal muscle lipids are key molecular determinants of insulin action, yet their involvement in the development of glucotoxicity is unclear.

OBJECTIVE

To explore the impact of mild physiologic hyperglycemia on skeletal muscle lipids.

DESIGN

Single group pretest-posttest.

PARTICIPANTS

Healthy males and females with normal glucose tolerance.

INTERVENTIONS

72-hour glucose infusion raising plasma glucose by ~50 mg/dL.

MAIN OUTCOME MEASURES

Skeletal muscle lipids, insulin sensitivity, lipid oxidation.

RESULTS

Despite impairing insulin-mediated glucose disposal and suppressing fasting lipid oxidation, hyperglycemia did not alter either the content or composition of skeletal muscle triglycerides, diacylglycerides, or phospholipids. Skeletal muscle ceramides decreased after glucose infusion, likely in response to a reduction in free fatty acid concentrations.

CONCLUSIONS

Our results demonstrate that the major lipid pools in skeletal muscle are unperturbed by sustained increases in glucose availability and suggest that glucotoxicity and lipotoxicity drive insulin resistance through distinct mechanistic pathways.

Incorporation of Oxidized Phenylalanine Derivatives into Insulin Signaling Relevant Proteins May Link Oxidative Stress to Signaling Conditions Underlying Chronic Insulin Resistance

A link between oxidative stress and insulin resistance has been suggested. Hydroxyl free radicals are known to be able to convert phenylalanine (Phe) into the non-physiological tyrosine isoforms ortho- and meta-tyrosine (o-Tyr, m-Tyr). The aim of our study was to examine the role of o-Tyr and m-Tyr in the development of insulin resistance. We found that insulin-induced uptake of glucose was blunted in cultures of 3T3-L1 grown on media containing o- or m-Tyr. We show that these modified amino acids are incorporated into cellular proteins. We focused on insulin receptor substrate 1 (IRS-1), which plays a role in insulin signaling. The activating phosphorylation of IRS-1 was increased by insulin, the effect of which was abolished in cells grown in m-Tyr or o-Tyr media. We found that phosphorylation of m- or o-Tyr containing IRS-1 segments by insulin receptor (IR) kinase was greatly reduced, PTP-1B phosphatase was incapable of dephosphorylating phosphorylated m- or o-Tyr IRS-1 peptides, and the SH2 domains of phosphoinositide 3-kinase (PI3K) bound the o-Tyr IRS-1 peptides with greatly reduced affinity. According to our data, m- or o-Tyr incorporation into IRS-1 modifies its protein–protein interactions with regulating enzymes and effectors, thus IRS-1 eventually loses its capacity to play its role in insulin signaling, leading to insulin resistance.

Role of Oxidative Stress in Diabetic Cardiomyopathy

Type 2 diabetes is a redox disease. Oxidative stress and chronic inflammation induce a switch of metabolic homeostatic set points, leading to glucose intolerance. Several diabetes-specific mechanisms contribute to prominent oxidative distress in the heart, resulting in the development of diabetic cardiomyopathy. Mitochondrial overproduction of reactive oxygen species in diabetic subjects is not only caused by intracellular hyperglycemia in the microvasculature but is also the result of increased fatty oxidation and lipotoxicity in cardiomyocytes. Mitochondrial overproduction of superoxide anion radicals induces, via inhibition of glyceraldehyde 3-phosphate dehydrogenase, an increased polyol pathway flux, increased formation of advanced glycation end-products (AGE) and activation of the receptor for AGE (RAGE), activation of protein kinase C isoforms, and an increased hexosamine pathway flux. These pathways not only directly contribute to diabetic cardiomyopathy but are themselves a source of additional reactive oxygen species. Reactive oxygen species and oxidative distress lead to cell dysfunction and cellular injury not only via protein oxidation, lipid peroxidation, DNA damage, and oxidative changes in microRNAs but also via activation of stress-sensitive pathways and redox regulation. Investigations in animal models of diabetic cardiomyopathy have consistently demonstrated that increased expression of the primary antioxidant enzymes attenuates myocardial pathology and improves cardiac function.

An Overview of Glycosylation and its Impact on Cardiovascular Health and Disease

The cardiovascular system is a complex and well-organized system in which glycosylation plays a vital role. The heart and vascular wall cells are constituted by an array of specific receptors; most of them are N- glycosylated and mucin-type O-glycosylated. There are also intracellular signaling pathways regulated by different post-translational modifications, including O-GlcNAcylation, which promote adequate responses to extracellular stimuli and signaling transduction. Herein, we provide an overview of N-glycosylation and O-glycosylation, including O-GlcNAcylation, and their role at different levels such as reception of signal, signal transduction, and exogenous molecules or agonists, which stimulate the heart and vascular wall cells with effects in different conditions, like the physiological status, ischemia/reperfusion, exercise, or during low-grade inflammation in diabetes and aging. Furthermore, mutations of glycosyltransferases and receptors are associated with development of cardiovascular diseases. The knowledge on glycosylation and its effects could be considered biochemical markers and might be useful as a therapeutic tool to control cardiovascular diseases.

The β-cell glucose toxicity hypothesis: Attractive but difficult to prove

β cells in the hyperglycemic environment of diabetes have marked changes in phenotype and function that are largely reversible if glucose levels can be returned to normal. A leading hypothesis is that these changes are caused by the elevated glucose levels leading to the concept of glucose toxicity. Support for the glucose toxicity hypothesis is largely circumstantial, but little progress has been made in defining the responsible mechanisms. Then questions emerge that are difficult to answer. In the very earliest stages of diabetes development, there is a dramatic loss of glucose-induced first-phase insulin release (FPIR) with only trivial elevations of blood glucose levels. A related question is how impaired insulin action on target tissues such as liver, muscle and fat can cause increased insulin secretion. The existence of a sophisticated feedback mechanism between insulin secretion and insulin action on peripheral tissues driven by glucose has been postulated, but it has been difficult to measure increases in blood glucose levels that might have been expected. These complexities force us to challenge the simplicity of the glucose toxicity hypothesis and feedback mechanisms. It may turn out that glucose is somehow driving all of these changes, but we must develop new questions and experimental approaches to test the hypothesis.

Insulin secretion is a strong predictor for need of insulin therapy in patients with new-onset diabetes and HbA1c of more than 10%: A post hoc analysis of the EDICT study

AIM

To identify predictors of response to glucose-lowering therapy in patients with new-onset diabetes and very high HbA1c (>10%).

METHODS

The study included EDICT participants with an initial HbA1c of more than 10% (N = 104). All subjects received a 75-g oral glucose tolerance test (OGTT) before initiation of therapy, and then were randomized to receive: (a) initial triple therapy with metformin, pioglitazone and exenatide versus (b) stepwise conventional therapy with metformin followed by glipizide and then glargine insulin to reduce HbA1c to less than 6.5%. Insulin secretion and insulin resistance were calculated with OGTT-derived indices.

RESULTS

Sixty-one per cent of participants in the conventional therapy group achieved HbA1c of less than 6.5% at 6 months without need of insulin therapy compared with 78% in the triple therapy group (P = NS). Insulin secretion at baseline was the strongest predictor of subjects who did not require insulin therapy; a cut point of CPEP₁₂₀ /CPEP₀ -the ratio between plasma C-peptide concentration at 120 minutes during the OGTT and fasting plasma C-peptide concentration-of more than 1.7 predicted subjects who achieved the treatment target without insulin, irrespective of the fasting plasma glucose (FPG) concentration and whether or not they were started on conventional or triple therapy. Subjects with a CPEP₁₂₀ /CPEP₀ of less than 1.7 plus FPG of 269 mg/dL or less (≤14.9 mmoL/L) also achieved the treatment goal with triple therapy.

CONCLUSION

Insulin secretion in response to a 75-g OGTT predicts the need for insulin therapy at the time of type 2 diabetes (T2D) diagnosis. A cut point of 1.7 of CPEP₁₂₀ /CPEP₀ provides a useful clinical tool to individualize glucose-lowering therapy in patients with new-onset T2D and HbA1c of more than 10%.

Long-term preoperative glycemic control restored the perioperative neutrophilic phagocytosis activity in diabetic mice

BACKGROUND

The risk of surgical site infection has been reported to be higher in patients with poorly controlled diabetes. Since chronic hyperglycemia impairs neutrophil functions, preoperative glycemic control may restore neutrophil function. However, long-term insulin therapy may lead to a delay in surgery, which may be a problem, especially in cancer surgery. It is therefore unfortunate that there have been few studies in which the optimal duration of perioperative glycemic control for diabetes with chronic hyperglycemia was investigated. Therefore, we investigated the effects of preoperative long-term insulin therapy and short-term insulin therapy on perioperative neutrophil functions in diabetic mice with chronic hyperglycemia.

METHODS

Five-week-old male C57BL/6 J mice were divided into four groups (No insulin (Diabetes Mellitus: DM), Short-term insulin (DM), Long-term insulin (DM), and Non-diabetic groups). Diabetes was established by administrating repeated low-dose streptozotocin. The Short-term insulin (DM) group received insulin therapy for 6 h before the operation and the Long-term insulin (DM) group received insulin therapy for 5 days before the operation. The No insulin (DM) group and the Non-diabetic group did not receive insulin therapy. At 14 weeks of age, abdominal surgery with intestinal manipulation was performed in all four groups. We carried out a phagocytosis assay with fluorescent microspheres and a reactive oxygen species (ROS) production assay with DCFH-DA (2',7'-dichlorodihydrofluorescein diacetate) before and 24 h after the operation using FACSVerse™ with BD FACSuite™ software.

RESULTS

Blood glucose was lowered by insulin therapy in the Short-term insulin (DM) and Long-term insulin (DM) groups before the operation. Neutrophilic phagocytosis activities before and after the operation were significantly restored in the Long-term insulin (DM) group compared with those in the No insulin (DM) group (before: p = 0.0008, after: p = 0.0005). However, they were not significantly restored in the Short-term insulin (DM) group. Neutrophilic ROS production activities before and after the operation were not restored in either the Short-term insulin (DM) group or Long-term insulin (DM) group.

CONCLUSIONS

Preoperative and postoperative phagocytosis activities are restored by insulin therapy for 5 days before the operation but not by insulin therapy for 6 h before the operation.

Cardiometabolic-Based Chronic Disease, Adiposity and Dysglycemia Drivers: JACC State-of-the-Art Review

A new cardiometabolic-based chronic disease (CMBCD) model is presented that provides a basis for early and sustainable, evidence-based therapeutic targeting to promote cardiometabolic health and mitigate the development and ravages of cardiovascular disease. In the first part of this JACC State-of-the-Art Review, a framework is presented for CMBCD, focusing on 3 primary drivers (genetics, environment, and behavior) and 2 metabolic drivers (adiposity and dysglycemia) with applications to 3 cardiovascular endpoints (coronary heart disease, heart failure, and atrial fibrillation). Specific mechanistic pathways are presented configuring early primary drivers with subsequent adiposity, insulin resistance, β-cell dysfunction, and metabolic syndrome, leading to cardiovascular disease. The context for building this CMBCD model is to expose actionable targets for prevention to achieve optimal cardiovascular outcomes. The tactical implementation of this CMBCD model is the subject of second part of this JACC State-of-the-Art Review.

Cardiometabolic-Based Chronic Disease, Adiposity and Dysglycemia Drivers: JACC State-of-the-Art Review

A new cardiometabolic-based chronic disease (CMBCD) model is presented that provides a basis for early and sustainable, evidence-based therapeutic targeting to promote cardiometabolic health and mitigate the development and ravages of cardiovascular disease. In the first part of this JACC State-of-the-Art Review, a framework is presented for CMBCD, focusing on 3 primary drivers (genetics, environment, and behavior) and 2 metabolic drivers (adiposity and dysglycemia) with applications to 3 cardiovascular endpoints (coronary heart disease, heart failure, and atrial fibrillation). Specific mechanistic pathways are presented configuring early primary drivers with subsequent adiposity, insulin resistance, β-cell dysfunction, and metabolic syndrome, leading to cardiovascular disease. The context for building this CMBCD model is to expose actionable targets for prevention to achieve optimal cardiovascular outcomes. The tactical implementation of this CMBCD model is the subject of second part of this JACC State-of-the-Art Review.

Rationale for Timely Insulin Therapy in Type 2 Diabetes Within the Framework of Individualised Treatment: 2020 Update

Type 2 diabetes is characterised by chronic hyperglycaemia and variable degrees of insulin deficiency and resistance. Hyperglycaemia and elevated fatty acids exert harmful effects on β-cell function, regeneration and apoptosis (gluco-lipotoxicity). Furthermore, chronic hyperglycaemia triggers a vicious cycle of insulin resistance, low-grade inflammation and a cascade of pro-atherogenic processes. Thus, timely near to normal glucose control is of utmost importance in the management of type 2 diabetes and prevention of micro- and macroangiopathy. The majority of patients are multimorbid and obese, with critical comorbidities such as cardiovascular disease, heart failure and chronic kidney disease. Recently published guidelines therefore recommend patient-centred risk/benefit-balanced use of oral glucose-lowering drugs or a glucagon-like peptide 1 (GLP-1) receptor agonist, or switching to insulin with glycated haemoglobin (HbA1c) out of target. This article covers the indications of early insulin treatment to prevent diabetes-related complications, particularly in subgroups with severe insulin deficit, and to achieve recovery of residual β-cell function. Furthermore, the individualised, risk/benefit-balanced, timely initiation of insulin as second and third option is analysed. Timely insulin initiation may prevent diabetes progression, reduce diabetes-related complications and has less serious adverse effects. Basal insulin is the preferred option in most clinical situations with consequences of undertreatment of chronic hyperglycaemia.

Glucolipotoxicity, β-Cells, and Diabetes: The Emperor Has No Clothes

Reduction of β-cell mass and function is central to the pathogenesis of type 2 diabetes. The terms glucotoxicity, lipotoxicity, and glucolipotoxicity are used to describe potentially responsible processes. The premise is that chronically elevated glucose levels are toxic to β-cells, that elevated lipid levels in the form of circulating free fatty acids (FFA) also have toxic effects, and that the combination of the two, glucolipotoxicity, is particularly harmful. Much work has shown that high concentrations of FFA can be very damaging to β-cells when used for in vitro experiments, and when infused in large amounts in humans and rodents they produce suppression of insulin secretion. The purpose of this Perspective is to raise doubts about whether the FFA levels found in real-life situations are ever high enough to cause problems. Evidence supporting the importance of glucotoxicity is strong because there is such a tight correlation between defective insulin secretion and rising glucose levels. However, there is virtually no convincing evidence that the alterations in FFA levels occurring during progression to diabetes are pathogenic. Thus, the terms lipotoxicity and glucolipotoxicity should be used with great caution, if at all, because evidence supporting their importance has not yet emerged.

Inadequate β-cell mass is essential for the pathogenesis of type 2 diabetes

For patients with type 1 diabetes, it is accepted among the scientific community that there is a marked reduction in β-cell mass; however, with type 2 diabetes, there is disagreement as to whether this reduction in mass occurs in every case. Some have argued that β-cell mass in some patients with type 2 diabetes is normal and that the cause of the hyperglycaemia in these patients is a functional abnormality of insulin secretion. In this Personal View, we argue that a deficient β-cell mass is essential for the development of type 2 diabetes. The main point is that there are enormous (≥10 fold) variations in insulin sensitivity and insulin secretion in the general population, with a very close correlation between these two factors for any individual. Although β-cell mass cannot be accurately measured in living patients, it is highly likely that it too is highly correlated with insulin sensitivity and secretion. Thus, our argument is that a person with type 2 diabetes can have a β-cell mass that is the same as a person without type 2 diabetes, but because they are insulin resistant, the mass is inadequate and responsible for their diabetes. Because the abnormal insulin secretion of diabetes is caused by dysglycaemia and can be largely reversed with glycaemic control, it is a less serious problem than the reduction in β-cell mass, which is far more difficult to restore.

Gadofullerene Nanoparticles Reverse Dysfunctions of Pancreas and Improve Hepatic Insulin Resistance for Type 2 Diabetes Mellitus Treatment

Type 2 diabetes mellitus (T2DM) has been one of the most prevalent metabolic disorders. Nonetheless, the commonly used anti-T2DM drugs failed to substant to treat T2DM when anti-T2DM was withdrawn. Here we put forward a superior and sustainable anti-diabetic strategy using intraperitoneal administration of amino-acid-functionalized gadofullerene nanoparticles (GFNPs) in db/db diabetic mice. Highly accumulated in the pancreas and liver, GFNPs could prominently decrease hyperglycemia, along with permanently maintaining normal blood sugar levels in T2DM mice and even stopping administration. Importantly, GFNPs reversed the pancreas islets dysfunctions by reducing oxidative stress and inflammation responses and fundamentally normalized the insulin secretory function of the pancreas islets. Mechanistically, GFNPs improved hepatic insulin resistance by regulating glucose and lipid metabolism through the activation of IRS2/PI3K/AKT signal pathways, resulting in inhibiting gluconeogenesis and increasing glycogenesis in the liver. Additionally, GFNPs relieved hepatic steatosis in the liver, ultimately maintaining systemic glucose and lipid metabolic homeostasis without obvious toxicity. Together, GFNPs reverse the dysfunctions of the pancreas and improve hepatic insulin resistance, providing a promising approach for T2DM treatment.

Barriers to the early initiation of Insulin therapy among diabetic patients coming to diabetic clinics of tertiary care hospitals

Background and Objective:

Initiation of Insulin therapy during earlier stages has proved to significantly improve health outcomes among diabetics in comparison to oral medications. Not only patients but physicians are also often resistant to early initiation of insulin therapy. The objective was to assess misconceptions and barriers to early initiation of insulin therapy among diabetic patients coming to a diabetic clinic.

Methods:

This cross sectional study was conducted on 300 patients selected by convenience sampling arriving in Diabetes Outdoor Clinics of Mayo and Services Hospitals, Lahore during August 2017 to May 2018. The data was entered and analyzed by using SPSS version 17.

Results:

Out of 300 patients included in study, 39% (n= 117) were males and 61% (n=183) were females. The mean age of the participants at presentation was 48.46±13.15 years with a range of 13 to 80 years. Study participants considered it embarrassing to inject insulin in public place (p-value 0.01). The fear associated with lifelong commitment to insulin therapy once it is started, was also found statistically significant (p-value 0.001)particularly in subjects who have long duration of DM (>5 years).

Conclusion:

Perceptions of diabetic patients about insulin therapy are still barriers to early initiation of therapy and tend to prevail in Pakistan and around the globe.

Effect of Chronic Hyperglycemia on Glucose Metabolism in Subjects With Normal Glucose Tolerance

Chronic hyperglycemia causes insulin resistance, but the inheritability of glucotoxicity and the underlying mechanisms are unclear. We examined the effect of 3 days of hyperglycemia on glucose disposal, enzyme activities, insulin signaling, and protein O-GlcNAcylation in skeletal muscle of individuals without (FH^-) or with (FH⁺) family history of type 2 diabetes. Twenty-five subjects with normal glucose tolerance received a [3-³H]glucose euglycemic insulin clamp, indirect calorimetry, and vastus-lateralis biopsies before and after 3 days of saline (n = 5) or glucose (n = 10 FH^- and 10 FH⁺) infusion to raise plasma glucose by ∼45 mg/dL. At baseline, FH⁺ had lower insulin-stimulated glucose oxidation and total glucose disposal (TGD) but similar nonoxidative glucose disposal and basal endogenous glucose production (bEGP) compared with FH^- After 3 days of glucose infusion, bEGP and glucose oxidation were markedly increased, whereas nonoxidative glucose disposal and TGD were lower versus baseline, with no differences between FH^- and FH⁺ subjects. Hyperglycemia doubled skeletal muscle glycogen content and impaired activation of glycogen synthase (GS), pyruvate dehydrogenase, and Akt, but protein O-GlcNAcylation was unchanged. Insulin resistance develops to a similar extent in FH^- and FH⁺ subjects after chronic hyperglycemia, without increased protein O-GlcNAcylation. Decreased nonoxidative glucose disposal due to impaired GS activation appears to be the primary deficit in skeletal muscle glucotoxicity.

Study of the effect of the herbal composition SR2004 on hemoglobin A1c, fasting blood glucose, and lipids in patients with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by raised blood glucose levels and peripheral insulin resistance. It is an increasingly prevalent global healthcare concern. Conventional treatment options are limited and in this context, there is renewed interest in evaluating the clinical and biological effects of traditional therapies. We assess the effect of a new herbal composition SR2004 on the hemoglobin A1c (HbA1c), fasting blood glucose, and lipid profiles of patients with T2DM.

Methods

This is a single center, unblinded, prospective interventional study conducted in Israel. The composition SR2004 includes Morus alba, Artemisia dracunculus, Urtica dioica, Cinnamomum zeylanicum, and Taraxacum officinale. One hundred and nineteen patients with diagnosed T2DM were enrolled and received SR2004 in addition to their usual medications. HbA1c, fasting blood glucose, and lipid profiles at 12 weeks were compared with baseline. In addition, the tolerability and side effects of SR2004 were recorded.

Results

One hundred and three patients completed 12 weeks of follow-up (87%) and were included in the results. At 12 weeks, HbA1c reduced from 9.0% to 7.1% (22%; p < 0.0001), mean blood glucose decreased from 211 mg/dL to 133 mg/dL (37% reduction; p < 0.0001), mean total cholesterol to 185 mg/dL (13% reduction; p < 0.01) and mean serum triglycerides to160 mg/dL (a reduction of 40% from baseline; p < 0.001). Twelve patients (12%) had no response with SR2004 supplementation. In addition, of thirteen patients who took insulin at baseline, five required only oral hypoglycemics and another five reduced their daily insulin requirements by 30% at 12 weeks. Clinical observations included improvements in vasculopathy, including reversal of established retinopathic changes in two patients.

No major adverse effects were observed, with minor abdominal symptoms reported in sixteen patients (16%).

Conclusion

SR2004 supplementation significantly reduced HbA1c, blood glucose, and lipids with good tolerability and no observed adverse interactions with conventional medications. Some interesting findings relating to the reversal of microvascular phenomena warrant further research to elucidate the mechanisms of action of this novel composition.

Short-term insulin intensive therapy decreases MCP-1 and NF-κB expression of peripheral blood monocyte and the serum MCP-1 concentration in newlydiagnosed type 2 diabetics

OBJECTIVE

To observe the effect of short-term insulin intensive treatment on the monocyte chemoattractant protein-1 (MCP-1) as well as on the nuclear factor-kappa B (NF-κB) expression of peripheral blood monocyte. This is also in addition to observing the serum MCP-1 level in newlydiagnosed type 2 diabetic patients and probing its anti-inflammation effects.

SUBJECTS AND METHODS

Twenty newly-diagnosed type 2 diabetic patients were treated with an insulin intensive treatment for 2 weeks. MCP-1 and NF-κB expression on the monocyte surface were measured with flow cytometry, the serum MCP-1 level was measured by enzyme linked immunosorbent assay (ELISA) during pretreatment and post-treatment.

RESULTS

After 2 weeks of the treatment, MCP-1 and NF-κB protein expression of peripheral blood monocyte and serum MCP-1 levels decreased significantly compared with those of pre-treatment, which were (0.50 ± 0.18)% vs (0.89 ± 0.26)% (12.22 ± 2.80)% vs (15.53 ± 2.49)% and (44.53 ± 3.97) pg/mL vs (49.53 ± 3.47) pg/mL, respectively (P < 0.01). The MCP-1 expression on monocyte surface had a significant positive relationship with serum MCP-1 levels (r = 0.47, P < 0.01).

CONCLUSIONS

Short-term insulin intensive therapy plays a role in alleviating the increased inflammation reaction in type 2 diabetics.

Empagliflozin Treatment Is Associated With Improved β-Cell Function in Type 2 Diabetes Mellitus

OBJECTIVE

To examine whether lowering plasma glucose concentration with the sodium-glucose transporter-2 inhibitor empagliflozin improves β-cell function in patients with type 2 diabetes mellitus (T2DM).

METHODS

Patients with T2DM (N = 15) received empagliflozin (25 mg/d) for 2 weeks. β-Cell function was measured with a nine-step hyperglycemic clamp (each step, 40 mg/dL) before and at 48 hours and at 14 days after initiating empagliflozin.

RESULTS

Glucosuria was recorded on days 1 and 14 [mean ± standard error of the mean (SEM), 101 ± 10 g and 117 ± 11 g, respectively] after initiating empagliflozin, as were reductions in fasting plasma glucose levels (25 ± 6 mg/dL and 38 ± 8 mg/dL, respectively; both P < 0.05). After initiating empagliflozin and during the stepped hyperglycemic clamp, the incremental area under the plasma C-peptide concentration curve increased by 48% ± 12% at 48 hours and 61% ± 10% at 14 days (both P < 0.01); glucose infusion rate increased by 15% on day 3 and 16% on day 14, compared with baseline (both P < 0.05); and β-cell function, measured with the insulin secretion/insulin resistance index, increased by 73% ± 21% at 48 hours and 112% ± 20% at 14 days (both P < 0.01). β-cell glucose sensitivity during the hyperglycemic clamp was enhanced by 42% at 14 hours and 54% at 14 days after initiating empagliflozin (both P < 0.01).

CONCLUSION

Lowering the plasma glucose concentration with empagliflozin in patients with T2DM augmented β-cell glucose sensitivity and improved β-cell function.

Relationship of Circulating miRNAs with Insulin Sensitivity and Associated Metabolic Risk Factors in Humans

BACKGROUND

Insulin resistance disrupts metabolic processes and leads to various chronic disease states such as diabetes and metabolic syndrome (MetS). However, the mechanism linking insulin resistance with cardiometabolic disease pathophysiology is still unclear. One possibility may be through circulating microRNAs (c-miRs), which can alter gene expression in target tissues. Our goal was to assess the relationship of c-miRs with insulin sensitivity, as measured by the gold standard, hyperinsulinemic-euglycemic clamp technique.

METHODS

Eighty-one nondiabetic, sedentary, and weight-stable patients across a wide range of insulin sensitivities were studied. Measurements were taken for blood pressure, anthropometric data, fasting glucose and lipids, and insulin sensitivity measured by clamp. After an initial screening array to identify candidate miRs in plasma, all samples were assessed for relationships between these c-miRs and insulin sensitivity, as well as associated metabolic factors.

RESULTS

miR-16 and miR-107 were positively associated with insulin sensitivity (R2 = 0.09, P = 0.0074 and R2 = 0.08, P = 0.0417, respectively) and remained so after adjustment with body mass index (BMI). After adjusting for BMI, miR-33, -150, and -222 were additionally found to be related to insulin sensitivity. Regarding metabolic risk factors, miR-16 was associated with waist circumference (r = -0.25), triglycerides (r = -0.28), and high-density lipoprotein (r = 0.22), while miR-33 was inversely associated with systolic blood pressure (r = -0.29). No significant relationships were found between any candidate c-miRs and BMI, diastolic blood pressure, or fasting glucose.

CONCLUSIONS

Our results show that relative levels of circulating miR-16, -107, -33, -150, and -222 are associated with insulin sensitivity and metabolic risk factors, and suggest that multiple miRs may act in concert to produce insulin resistance and the clustering of associated traits that comprise the MetS. Therefore, miRs may have potential as novel therapeutic targets or agents in cardiometabolic disease.

Novel route of insulin delivery using an implant-mediated drug delivery system

Patients with diabetes mellitus (DM) frequently require multiple painful injections of insulin to manage their blood glucose level. A newly introduced, modified titanium implant, the implant-mediated drug delivery system (IMDDS), has the advantage of sustained, needle-free drug delivery. We evaluated the feasibility of the IMDDS as an alternative route of insulin delivery in an alloxan-induced rabbit DM model. Among a total of 30 rabbits with IMDDSs, 25 survived the induction and had a blood glucose level (BGL) higher than 300 mg/dl. The animals were divided into two groups: 13 in the test group to which insulin was administered via the IMDDS and 12 in the untreated control group. The BGL was monitored and measured at 0, 2, 4, 6, 8, 12, and 24 hours on the first day and every 12 hours thereafter for a total of 2 weeks. Marked hypoglycemic effects of insulin in the test rabbits were detected from the 2-h time point, and the mean BGL fell below the normal range from 12 h after insulin administration via the IMDDS. The effects lasted the entire 2-week period. Control rabbits did not show a pronounced decrease in BGL except for three animals who exhibited spontaneous recovery. The mean body weight of the test group was significantly higher than that of the control group at the end of the observation period. Although this implant requires several improvements, the IMDDS exhibited promise as an alternative route of insulin delivery with the advantages of being a sustained, needle-free insulin delivery system.

Efficacy of Exenatide Plus Pioglitazone Vs Basal/Bolus Insulin in T2DM Patients With Very High HbA1c

OBJECTIVE

To examine the efficacy and safety of combination therapy with exenatide plus pioglitazone vs basal/bolus insulin in patients with poorly controlled type 2 diabetes mellitus (T2DM) with very high hemoglobin A1c (HbA1c) (>10%) receiving sulfonylurea plus metformin and with a long duration of disease.

DESIGN AND PARTICIPANTS

Participants (n = 101) in the Qatar Study with very poor glycemic control (HbA1c >10%) and a long duration of diabetes (10.9 years) receiving maximum/near-maximum doses of sulfonylurea plus metformin were randomly assigned to receive pioglitazone plus weekly exenatide (combination therapy), or basal plus prandial insulin (insulin therapy), to maintain HbA1c <7.0%.

RESULTS

Baseline HbA1c was 11.5% ± 0.2% and 11.2% ± 0.2% (P = not significant) in combination therapy and insulin therapy groups, respectively. At 6 months, combination therapy caused a robust decrease in HbA1c to 6.7% ± 0.1% (∆ = -4.8%) compared with 7.4% ± 0.1% (∆ = -3.8%) in subjects receiving insulin therapy. Combination therapy was effective in lowering the HbA1c independent of sex, ethnicity, or body mass index. Subjects in the insulin therapy group experienced significantly greater weight gain and a 2.5-fold higher rate of hypoglycemia compared with patients receiving combination therapy.

CONCLUSION

Exenatide/pioglitazone combination therapy is an effective and safe therapeutic option in patients with poorly controlled T2DM receiving metformin plus sulfonylurea with very high HbA1c (>10%).

Insulin Secretion and Glucose Tolerance after Islet Transplantation in Rats with Noninsulin-Dependent Diabetes Induced by Neonatal Streptozotocin

The present study was designed to identify in a model of noninsulin-dependent diabetes induced by neonatal streptozotocin (n0-STZ), the long-term consequences of an islet graft upon 1) glucose handling of the recipient and, 2) glucose response of the residual β cells in the recipient pancreas. We have examined, 4 and 8 wk after islet implantation under the kidney capsule of syngeneic diabetic n0-STZ rats, their tolerance to glucose administered in vivo, together with their insulin release in response to glucose in vivo (oral glucose tolerance test) as well as in vitro (perfused pancreas). The results in the islet-grafted n0-STZ rats, were compared to those obtained in nongrafted nondiabetic rats and nongrafted n0-STZ rats. Our study shows that transplanting a limited number (900) of adult islets under the kidney capsule reverses to normal, many parameters of the noninsulin-dependent diabetic state in the n0-STZ rat model: these include body weight, basal plasma glucose in both the nonfasted and postabsorptive states, and basal plasma insulin in the postabsorptive state. Furthermore, tolerance to oral glucose administration was greatly improved in the transplanted rats and it was correlated with restoration of a manifest glucose-induced insulin secretion in vivo as evaluated (ΔI) during an oral glucose tolerance test. Our data clearly show that the insulin response to glucose from the endogenous pancreas of n0-STZ diabetic rat was not really improved by long-term (8 wk) basal normoglycemia. More precisely, we were able to detect a slight but significant improvement of the early phase of insulin release in vitro in response to glucose; however, the overall insulin response remained 15 times lower than the normal one with no reapparance of the late phase of insulin release. After cessation of glucose stimulation in vivo, off-response of insulin, which is also a landmark of the impaired insulin release by the β cells of n0-STZ rats, was still detectable in the perfused pancreas of the transplanted n0-STZ rats. Finally, because the reactivity to glucose of the endogenous residual β cells was not regained, the insulin released in vivo during the oral glucose test in the graft-bearing n0-STZ rats can be attributed mainly to functioning of the grafted islets population. Copyright © 1997 Elsevier Science Inc.

Impact of insulin sensitivity, beta-cell function and glycaemic control on initiation of second-line glucose-lowering treatment in newly diagnosed type 2 diabetes

AIMS

The aim of this study was to investigate whether insulin sensitivity, beta-cell function or glycaemic control at diagnosis predict initiation of second-line treatment in newly diagnosed type 2 diabetes.

RESEARCH DESIGN AND METHODS

Type 2 diabetes patients (n = 138) undergoing initial metformin monotherapy (age [mean ± SD], 52 ± 10 years; 67% males; BMI, 32 ± 6 kg/m² ) from the prospective German Diabetes Study cohort (n = 398) were included. Patients remained under care of their general practitioners, yet underwent detailed metabolic characterization after diabetes diagnosis for study purposes (hyperinsulinemic-euglycemic clamp, M value; i.v. glucose tolerance test, incremental C-peptide area under the curve_{0-60 minutes,} CP iAUC). The associations of baseline M value, CP iAUC, fasting glucose and HbA1c with time to second-line therapy were assessed using parametric survival analysis, accounting for interval-censoring.

RESULTS

Second-line treatment was initiated in 26% of newly diagnosed type 2 diabetes patients within the first 3.3 years after diagnosis, using mostly DPP-4 inhibitors or GLP-1 receptor agonists (64%). In age-, sex- and BMI-adjusted survival models, higher baseline HbA1c and fasting glucose values were associated with earlier treatment intensification. Lower baseline M value and C-peptide secretion (CP iAUC) were also related to an earlier initiation of second-line treatment. In the best multivariable model, baseline HbA1c ≥ 7% (hazard ratio, HR; 95% CI: 3.18; 1.35-7.50) and fasting glucose ≥140 mg/dL (HR, 2.45; 95% CI, 1.04-5.78) were associated with shorter time to second-line therapy, adjusting for age, sex and BMI.

CONCLUSIONS

Baseline hyperglycaemia is a strong predictor of requirement of early intensification of glucose-lowering therapy in newly diagnosed type 2 diabetes.

F2-Isoprostanes Reflect Oxidative Stress Correlated With Lean Mass and Bone Density but Not Insulin Resistance

Context:

F2-isoprostanes (F2-isoPs) are biomarkers for oxidative stress in humans and have been shown to be elevated in obesity, cardiovascular disease, and diabetes. Therefore, F2-isoPs are often implicated in oxidative stress contributing to insulin resistance, although this has not been rigorously examined.

Objective:

To determine whether urinary F2-isoPs are predictive of insulin sensitivity and other clinical metabolic parameters.

Participants:

Sedentary, weight-stable, nondiabetic adults equilibrated on a standard isocaloric diet.

Main Outcome Measures:

Insulin sensitivity via hyperinsulinemic-euglycemic clamp, urinary F2-isoPs by gas chromatography-mass spectrometry, and body composition by dual-energy x-ray absorptiometry.

Results:

No correlation was found between 15-F_2t-IsoP nor its major metabolite, 2,3-dinor-5,6-dihydro-15-F_2t-IsoP, with insulin sensitivity, even after adjusting for age, race, sex, BMI, and smoking status. 15-F_2t-IsoP was also not associated with body fat. However, there was a strong negative correlation between 15-F_2t-IsoP and lean body mass (LBM; r = −0.46, P = 0.0001), bone mineral content (BMC; r = −0.58, P < 0.0001), bone mineral density (BMD; r = −0.65, P < 0.0001), and skeletal muscle protein 4-hydroxynonenal (4-HNE; r = −0.54, P = 0.0239), another marker of oxidative stress. 15-F_2t-IsoP was also positively associated with circulating triglycerides and total cholesterol, and increased as a function of age.

Conclusions:

Urinary 15-F_2t-IsoP and its major metabolite are not associated with insulin sensitivity, suggesting the lipid peroxidation process that produces F2-isoPs does not reflect oxidative stress reactions operative in insulin resistance. However, urinary F2-isoPs were negatively correlated with LBM, BMC, BMD, and muscle 4-HNE. Because lean and bone mass decline as a function of biological aging, F2-isoPs may reflect the oxidative stress operative in the aging process.

Metabolic Stress and Compromised Identity of Pancreatic Beta Cells

Beta cell failure is a central feature of type 2 diabetes (T2D), but the molecular underpinnings of the process remain only partly understood. It has been suggested that beta cell failure in T2D involves massive cell death. Other studies ascribe beta cell failure to cell exhaustion, due to chronic oxidative or endoplasmic reticulum stress leading to cellular dysfunction. More recently it was proposed that beta cells in T2D may lose their differentiated identity, possibly even gaining features of other islet cell types. The loss of beta cell identity appears to be driven by glucotoxicity inhibiting the activity of key beta cell transcription factors including Pdx1, Nkx6.1, MafA and Pax6, thereby silencing beta cell genes and derepressing alternative islet cell genes. The loss of beta cell identity is at least partly reversible upon normalization of glycemia, with implications for the reversibility of T2D, although it is not known if beta cell failure reaches eventually a point of no return. In this review we discuss current evidence for metabolism-driven compromised beta cell identity, key knowledge gaps and opportunities for utility in the treatment of T2D.

Glucose Driven Changes in Beta Cell Identity Are Important for Function and Possibly Autoimmune Vulnerability during the Progression of Type 1 Diabetes

This commentary explores the hypothesis that when autoimmunity leads to a fall of beta cell mass during the progression of type 1 diabetes (T1D), rising glucose levels cause major changes in beta cell identity. This then leads to profound changes in secretory function and less well-understood changes in beta cell susceptibility to autoimmune destruction, which may influence of rate of progression of beta cell killing.

Reduction of Sulfonylurea with the Initiation of Basal Insulin in Patients with Inadequately Controlled Type 2 Diabetes Mellitus Undergoing Long-Term Sulfonylurea-Based Treatment

BACKGROUND

There were a limited number of studies about β-cell function after insulin initiation in patients exposed to long durations of sulfonylurea treatment. In this study, we aimed to evaluate the recovery of β-cell function and the efficacy of concurrent sulfonylurea use after the start of long-acting insulin.

METHODS

In this randomized controlled study, patients with type 2 diabetes mellitus (T2DM), receiving sulfonylurea for at least 2 years with glycosylated hemoglobin (HbA1c) >7%, were randomly assigned to two groups: sulfonylurea maintenance (SM) and sulfonylurea reduction (SR). Following a 75-g oral glucose tolerance test (OGTT), we administered long-acting basal insulin to the two groups. After a 6-month follow-up, we repeated the OGTT.

RESULTS

Among 69 enrolled patients, 57 completed the study and were analyzed: 31 in the SM and 26 in the SR group. At baseline, there was no significant difference except for the longer duration of diabetes and lower triglycerides in the SR group. After 6 months, the HbA1c was similarly reduced in both groups, but there was little difference in the insulin dose. In addition, insulin secretion during OGTT was significantly increased by 20% to 30% in both groups. A significant weight gain was observed in the SM group only. The insulinogenic index was more significantly improved in the SR group.

CONCLUSION

Long-acting basal insulin replacement could improve the glycemic status and restore β-cell function in the T2DM patients undergoing sulfonylurea-based treatment, irrespective of the sulfonylurea dose reduction. The dose reduction of the concurrent sulfonylurea might be beneficial with regard to weight grain.

Pancreatic β-cell identity in diabetes

Recovery of functional β-cell mass continues to be an ongoing challenge in treating diabetes. Initial work studying β-cells suggested apoptotic β-cell death as a main contributor for the loss of β-cell mass in diabetes. Restoration of β-cells either by transplant or stimulating proliferation of remaining β-cells or precursors would then logically be a viable therapeutic option for diabetes. However, recent work has highlighted the inherent β-cell plasticity and the critical role of loss of β-cell identity in diabetes, and has suggested that β-cells fail to maintain a fully differentiated glucose-responsive and drug-responsive state, particularly in diabetic individuals with poorly controlled, long-lasting periods of hyperglycaemia. Understanding the underlying mechanisms of loss of β-cell identity and conversion in other cell types, as well as how to regain their mature differentiated functional state, is critical to develop novel therapeutic strategies to prevent or reverse these processes. In this review, we discuss the role of plasticity and loss of β-cell identity in diabetes, the current understanding of mechanisms involved in altering this mature functional β-cell state and potential progresses to identify novel therapeutic targets providing better opportunities for slowing or preventing diabetes progression.

Skeletal Muscle TRIB3 Mediates Glucose Toxicity in Diabetes and High- Fat Diet-Induced Insulin Resistance

In the current study, we used muscle-specific TRIB3 overexpressing (MOE) and knockout (MKO) mice to determine whether TRIB3 mediates glucose-induced insulin resistance in diabetes and whether alterations in TRIB3 expression as a function of nutrient availability have a regulatory role in metabolism. In streptozotocin diabetic mice, TRIB3 MOE exacerbated, whereas MKO prevented, glucose-induced insulin resistance and impaired glucose oxidation and defects in insulin signal transduction compared with wild-type (WT) mice, indicating that glucose-induced insulin resistance was dependent on TRIB3. In response to a high-fat diet, TRIB3 MOE mice exhibited greater weight gain and worse insulin resistance in vivo compared with WT mice, coupled with decreased AKT phosphorylation, increased inflammation and oxidative stress, and upregulation of lipid metabolic genes coupled with downregulation of glucose metabolic genes in skeletal muscle. These effects were prevented in the TRIB3 MKO mice relative to WT mice. In conclusion, TRIB3 has a pathophysiological role in diabetes and a physiological role in metabolism. Glucose-induced insulin resistance and insulin resistance due to diet-induced obesity both depend on muscle TRIB3. Under physiological conditions, muscle TRIB3 also influences energy expenditure and substrate metabolism, indicating that the decrease and increase in muscle TRIB3 under fasting and nutrient excess, respectively, are critical for metabolic homeostasis.

Impact of a mild decrease in fasting plasma glucose on β-cell function in healthy subjects and patients with type 2 diabetes

Restoring euglycaemia for weeks or months improves insulin secretion in patients with type 2 diabetes (T2D). We tested whether mild decrements in fasting glucose (FPG) acutely affect β-cell function and insulin sensitivity. Thirteen normotolerant (NGT) and 10 T2D patients volunteered in pairs. In an isoglycemic test (Iso), after 100 min of stabilization, an incremental glucose infusion over 3 h was applied to raise plasma glucose to >22 mmol/l, followed by an arginine challenge; in a subisoglycemic test (Sub), a glucose infusion matching the plasma glucose time course of Iso was preceded by an insulin infusion period (100 min) aimed at maintaining a mild FPG reduction while avoiding hypoglycaemia. β-Cell function was assessed by mathematical modeling, whereas the acute insulin response (AIR) to arginine was determined from C-peptide levels. In the Sub, FPG was lowered by 17% in NGT and 31% in T2D patients. On the glucose ramp, total insulin release was lower in Sub than in Iso in both groups [from 106 (43) to 75 (39) nmol/m(-2) in NGT and from 71 (63) to 64 (41) nmol/m(-2) in T2D, P = 0.001]. In the Sub, β-cell glucose sensitivity was significantly (P = 0.008) reduced in NGT [from 50 (31) to 43 (21) pmol·min(-1)·m(-2)·mM(-1)] but not in T2D [19 (20) to 20 (20) pmol·min(-1)·m(-2)·mM(-1)]. Likewise, AIR was lowered in NGT [8.9 (4.6) to 7.1 (4.4) nmol/l, P = 0.048] but not in T2D [4.7 (3.3) to 5.3 (3.2) nmol/l]. Insulin sensitivity improved in NGT but only marginally in T2D. Prestimulatory glucose levels acutely influence both β-cell function and insulin sensitivity differentially in nondiabetic and type 2 diabetic individuals.

Sustained efficacy of insulin pump therapy compared with multiple daily injections in type 2 diabetes: 12-month data from the OpT2mise randomized trial

AIMS

To compare insulin pump therapy and multiple daily injections (MDI) in patients with type 2 diabetes receiving basal and prandial insulin analogues.

METHODS

After a 2-month dose-optimization period, 331 patients with glycated haemoglobin (HbA1c) levels ≥8.0% and ≤12% were randomized to pump therapy or continued MDI for 6 months [randomization phase (RP)]. The MDI group was subsequently switched to pump therapy during a 6-month continuation phase (CP). The primary endpoint was the between-group difference in change in mean HbA1c from baseline to the end of the RP.

RESULTS

The mean HbA1c at baseline was 9% in both groups. At the end of the RP, the reduction in HbA1c was significantly greater with pump therapy than with MDI (-1.1 ± 1.2% vs -0.4 ± 1.1%; p < 0.001). The pump therapy group maintained this improvement to 12 months while the MDI group, which was switched to pump therapy, showed a 0.8% reduction: the final HbA1c level was identical in both arms. In the RP, total daily insulin dose (TDD) was 20.4% lower with pump therapy than with MDI and remained stable in the CP. The MDI-pump group showed a 19% decline in TDD, such that by 12 months TDD was equivalent in both groups. There were no differences in weight gain or ketoacidosis between groups. In the CP, one patient in each group experienced severe hypoglycaemia.

CONCLUSIONS

Pump therapy has a sustained durable effect on glycaemic control in uncontrolled type 2 diabetes.

The OPT2MISE Study - A Review of the Major Findings and Clinical Implications

Many patients with type 2 diabetes struggle to achieve adequate glucose control despite escalation of therapy including complex insulin regimens with multiple daily injections (MDIs). Previous randomised controlled trials failed to show a significant improvement in glycaemic control with pump therapy over multiple injections. The OPT2MISE study enrolled 495 adult patients with poorly controlled type 2 diabetes despite an intensified insulin regimen using rapid and slow-acting insulin analogues. After a 2-month run-in period, patients were randomised to switch to pump therapy or to maintain their MDI regimen. After 6 months, patients with pump therapy achieved a better glycaemic control than those who used multiple injections (glycated haemoglobin [HbA_1c] difference of −0.7 %), and twice as many patients reached the target range of 8 % or less in the pump-therapy group compared with the injection group. Patients using pump therapy had a 20 % reduction of their total daily insulin dose. A moderate weight gain was observed with both treatments, and no severe hypoglycaemia nor ketoacidosis occurred in the pump therapy group. Pump therapy may now be considered as a valuable option in type 2 diabetes patients who fail to respond to an intensified insulin regimen.

Weight Loss and the Prevention and Treatment of Type 2 Diabetes Using Lifestyle Therapy, Pharmacotherapy, and Bariatric Surgery: Mechanisms of Action

Weight loss, whether achieved by lifestyle intervention, pharmacotherapy, or bariatric surgery, is highly effective as a primary interventional strategy in both the prevention and treatment of type 2 diabetes. In high-risk patients with prediabetes and/or metabolic syndrome, weight loss effectively prevents progression to type 2 diabetes mellitus (T2DM) and improves cardiovascular risk factors. These benefits are the result of improvements in insulin resistance, which is central to the pathophysiology of cardiometabolic disease. In patients with T2DM, weight loss improves glycemia, while reducing the need for conventional glucose-lowering medicines, by affecting all three processes that produce and sustain the hyperglycemic state, namely via increments in peripheral insulin sensitivity with improvements in insulin signal transduction at the cellular level, more robust insulin secretory responses, and reduced rates of hepatic glucose production. In both nondiabetic and diabetic subjects, hypocaloric feeding (e.g., treatment with very low-calorie diet or bariatric surgery) produces a rapid improvement in insulin sensitivity due to mobilization of fat from the intramyocellular, intrahepatocellular, and intra-abdominal compartments, and via a more long-term mechanism that correlates with the loss of total body fat. In diabetes, by improving glycemia, weight loss also enhances glucose homeostasis by reversing the defects in insulin action and secretion attributable to glucose toxicity. Regardless of the therapeutic approach, weight loss of ∼ 10 % maximally prevents future diabetes in patients with prediabetes or metabolic syndrome. In T2DM, greater degrees of weight loss lead to progressive improvements in glucose homeostasis. Therefore, when accompanied by greater weight loss, the metabolic benefits following bariatric surgery are generally more pronounced than those achieved following lifestyle and medical treatment. In addition, the mechanisms by which bariatric operations improve diabetes may include both weight-dependent and weight-independent mechanisms, and the latter may involve changes in gut hormones, bile acids, or gut microflora.

Proinsulin-producing, hyperglycemia-induced adipose tissue macrophages underlie insulin resistance in high fat-fed diabetic mice

Adipose tissue macrophages (ATMs) play an important role in the pathogenesis of obese type 2 diabetes. High-fat diet (HFD)-induced obesity has been shown to lead to ATM accumulation in rodents; however, the impact of hyperglycemia on ATM dynamics in HFD-fed type 2 diabetic models has not been studied. We previously showed that hyperglycemia induces the appearance of proinsulin (PI)-producing proinflammatory bone marrow (BM)-derived cells (PI-BMDCs) in rodents. We fed a 60% HFD to C57BL6/J mice to produce an obese type 2 diabetes model. Absent in chow-fed animals, PI-BMDCs account for 60% of the ATMs in the type 2 diabetic mice. The PI-ATM subset expresses TNF-α and other inflammatory markers, and is highly enriched within crownlike structures (CLSs). We found that amelioration of hyperglycemia by different hypoglycemic agents forestalled PI-producing ATM accumulation and adipose inflammation in these animals. We developed a diphtheria toxin receptor-based strategy to selectively ablate PI-BMDCs among ATMs. Application of the maneuver in HFD-fed type 2 diabetic mice was found to lead to near total disappearance of complex CLSs and reversal of insulin resistance and hepatosteatosis in these animals. In sum, we have identified a novel ATM subset in type 2 diabetic rodents that underlies systemic insulin resistance.

Dapagliflozin lowers plasma glucose concentration and improves β-cell function

BACKGROUND

β-Cell dysfunction is a core defect in T2DM, and chronic, sustained hyperglycemia has been implicated in progressive β-cell failure, ie, glucotoxicity. The aim of the present study was to examine the effect of lowering the plasma glucose concentration with dapagliflozin, a glucosuric agent, on β-cell function in T2DM individuals.

RESEARCH DESIGN AND METHODS

Twenty-four subjects with T2DM received dapagliflozin (n = 16) or placebo (n = 8) for 2 weeks, and a 75-g oral glucose tolerance test (OGTT) and insulin clamp were performed before and after treatment. Plasma glucose, insulin, and C-peptide concentrations were measured during the OGTT.

RESULTS

Dapagliflozin significantly lowered both the fasting and 2-hour plasma glucose concentrations and the incremental area under the plasma glucose concentration curve (ΔG0-120) during OGTT by -33 ± 5 mg/dL, -73 ± 9 mg/dL, and -60 ± 12 mg/dL · min, respectively, compared to -13 ± 9, -33 ± 13, and -18 ± 9 reductions in placebo-treated subjects (both P < .01). The incremental area under the plasma C-peptide concentration curve tended to increase in dapagliflozin-treated subjects, whereas it did not change in placebo-treated subjects. Thus, ΔC-Pep0-120/ΔG0-120 increased significantly in dapagliflozin-treated subjects, whereas it did not change in placebo-treated subjects (0.019 ± 0.005 vs 0.002 ± 0.006; P < .01). Dapagliflozin significantly improved whole-body insulin sensitivity (insulin clamp). Thus, β-cell function, measured as ΔC-Pep0-120/ ΔG0-120 ÷ insulin resistance, increased by 2-fold (P < .01) in dapagliflozin-treated vs placebo-treated subjects.

CONCLUSION

Lowering the plasma glucose concentration with dapagliflozin markedly improves β-cell function, providing strong support in man for the glucotoxic effect of hyperglycemia on β-cell function.

Comparative effectiveness of early versus delayed metformin in the treatment of type 2 diabetes

AIM

The purpose of this study was to evaluate the effectiveness of early versus delayed initiation of metformin in type 2 diabetes.

METHODS

We identified 2925 new users of metformin with type 2 diabetes between 2005 and 2012 in the electronic health records of an integrated health system in Northern California. Patients were matched 1:1 on the propensity for receiving early treatment (defined as ≤6 months from first evidence of diabetes). We evaluated the effectiveness of early versus delayed metformin treatment on intermediate clinical outcomes indicated by changes in hemoglobin A1c (HbA1c) and body mass index (BMI), as well as the incidence of therapy intensification (addition or substitution of a second antihyperglycemic agent).

RESULTS

A total of 2144 propensity-score matched patients were included in the early or delayed treatment group (n=1072, in each). Early treatment was associated with significantly larger decreases in HbA1c (-0.36%; 95% confidence intervals [CI]: -0.44 to -0.27%; P<0.001) and BMI (-0.46 kg/m(2); 95% CI: -0.64 to -0.29 kg/m(2); P<0.001) relative to delayed treatment. Patients receiving early treatment also had a greater likelihood of attaining an HbA1c<7% (<53 mmol/mol) (odds ratio: 2.00; 95% CI: 1.63-2.45; P<0.001) and a reduced risk of therapy intensification (hazard ratio: 0.72; 95% CI: 0.61-0.85; P<0.001).

CONCLUSIONS

Treatment with metformin earlier in the course of type 2 diabetes is associated with better glycemic control, more pronounced weight reduction, and a lower risk for therapy intensification than delayed treatment. Antihyperglycemic therapy should be initiated early after diagnosis to achieve optimal outcomes.

Immediate enhancement of first-phase insulin secretion and unchanged glucose effectiveness in patients with type 2 diabetes after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass surgery (RYGB) in patients with type 2 diabetes often leads to early disease remission, and it is unknown to what extent this involves improved pancreatic β-cell function per se and/or enhanced insulin- and non-insulin-mediated glucose disposal (glucose effectiveness). We studied 30 obese patients, including 10 with type 2 diabetes, 8 with impaired glucose tolerance, and 12 with normal glucose tolerance before, 1 wk, and 3 mo after RYGB, using an intravenous glucose tolerance test (IVGTT) to estimate first-phase insulin response, insulin sensitivity (Si), and glucose effectiveness with Bergman's minimal model. In the fasting state, insulin sensitivity was estimated by HOMA-S and β-cell function by HOMA-β. Moreover, mixed-meal tests and oral GTTs were performed. In patients with type 2 diabetes, glucose levels normalized after RYGB, first-phase insulin secretion in response to iv glucose increased twofold, and HOMA-β already improved 1 wk postoperatively, with further enhancements at 3 mo. Insulin sensitivity increased in the liver (HOMA-S) at 1 wk and at 3 mo in peripheral tissues (Si), whereas glucose effectiveness did not improve significantly. During oral testing, GLP-1 responses and insulin secretion increased regardless of glucose tolerance. Therefore, in addition to increased insulin sensitivity and exaggerated postprandial GLP-1 levels, diabetes remission after RYGB involves early improvement of pancreatic β-cell function per se, reflected in enhanced first-phase insulin secretion to iv glucose and increased HOMA-β. A major role for improved glucose effectiveness after RYGB was not supported by this study.

Association between age at menarche and diabetes in Korean post-menopausal women: results from the Korea National Health and Nutrition Examination Survey (2007-2009)

Early menarche is known to be associated with diabetes, however this association remains controversial. Our study aimed to investigate the possible association between age at menarche and diabetes prevalence in post-menopausal Korean women. This study included 3,254 post-menopausal Korean women aged 50-85 years from the Korea National Health and Nutrition Examination Survey IV (KNHANES 2007-2009). Logistic regression analyses were used to estimate odds ratios (ORs) for diabetes prevalence. Levels of biochemical markers were compared according to groups by age at menarche. Women in the earlier menarche age group (10-12 years) showed higher levels of fasting blood glucose (FBG) and scores of homeostatic model assessment in the insulin resistance (HOMA-IR) index than other groups (p <0.05). After adjusting for potential confounding factors, early age at menarche was significantly associated with a higher prevalence of diabetes (OR 1.86, 95% confidence intervals [CI] 1.07-3.23). The observed association remained significant despite additional adjustment for body mass index and waist circumference (OR 1.82, 95% CI 1.03-3.23) and despite further adjustments for FBG levels and HOMA-IR index (OR 2.25, 95% CI 1.11-4.55). Our findings strengthen the hypothesis that younger age at menarche is associated with increased diabetes prevalence in the Korean population.

The time has come to test the beta cell preserving effects of exercise in patients with new onset type 1 diabetes

Type 1 diabetes is characterised by immune-mediated destruction of insulin-producing beta cells. Significant beta cell function is usually present at the time of diagnosis with type 1 diabetes, and preservation of this function has important clinical benefits. The last 30 years have seen a number of largely unsuccessful trials for beta cell preservation, some of which have been of therapies that have potential for significant harm. There is a need to explore new, more tolerable approaches to preserving beta cell function that can be implemented on a large clinical scale. Here we review the evidence for physical exercise as a therapy for the preservation of beta cell function in patients with newly diagnosed type 1 diabetes. We highlight possible mechanisms by which exercise could preserve beta cell function and then present evidence from other models of diabetes that demonstrate that exercise preserves beta cell function. We conclude by proposing that there is now a need for studies to explore whether exercise can preserve beta cell in patients newly diagnosed with type 1 diabetes.