Insulin therapy in insulin resistance: Could it be part of a lethal pathway?

Trends in insulin resistance: insights into mechanisms and therapeutic strategy

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into a medically manageable chronic condition. Insulin is a key peptide hormone and mediates the systemic glucose metabolism in different tissues. Insulin resistance (IR) is a disordered biological response for insulin stimulation through the disruption of different molecular pathways in target tissues. Acquired conditions and genetic factors have been implicated in IR. Recent genetic and biochemical studies suggest that the dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids and toxic lipid metabolites promote IR in other tissues. IR is associated with several groups of abnormal syndromes that include obesity, diabetes, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), and other abnormalities. Although no medication is specifically approved to treat IR, we summarized the lifestyle changes and pharmacological medications that have been used as efficient intervention to improve insulin sensitivity. Ultimately, the systematic discussion of complex mechanism will help to identify potential new targets and treat the closely associated metabolic syndrome of IR.

Impact of insulin therapy on outcomes of diabetic patients with heart failure: A systematic review and meta-analysis

OBJECTIVE

To compare clinical outcomes in diabetic patients with heart failure managed by insulin with those managed by non-insulin (oral hypoglycemic agents and/or lifestyle modification) based therapy.

METHODS

PubMed and Scopus databases were searched for studies conducted on diabetic patients with heart failure. Studies were to compare outcomes of patients managed by insulin versus non-insulin therapies.

RESULTS

15 studies were included. Compared to those who were managed using non-insulin therapy, insulin-treated patients had increased risk of all-cause mortality (RR 1.46, 95% CI: 1.14, 1.88) and cardiovascular specific mortality (RR 1.62, 95% CI: 1.33, 1.96). Those managed using insulin also had increased risk of hospitalization (RR 1.45, 95% CI: 1.09, 1.93) and readmission (RR 1.49, 95% CI: 1.32, 1.67). There was no additional risk for stroke (RR 1.07, 95% CI: 0.91, 1.27) or myocardial infarction (MI) (RR 1.10, 95% CI: 0.96, 1.27) between the two groups of patients.

CONCLUSIONS

Receipt of insulin among diabetic patients with heart failure was associated with an increased risk of mortality, hospitalization and readmission compared to management using oral hypoglycemic agents and/or lifestyle modification. Such patients should be closely monitored for any adverse events.

The Evaluation of Cardiovascular Risk in Diabetic Patients

AIM

The aim of the study was to evaluate cardiovascular risk in patients with diabetes mellitus type 2 according to gender.

METHODS

The monitoring was designed as a retrospective analysis of data obtained from the documentation of the diabetic outpatients treated with the dipeptidyl peptidase-4 inhibitors (DPP4is) or sodium–glucose co-transporter-2 (SGLT2). Cardiovascular risk was assessed according to UKPDS risk engine.

RESULTS

The levels of HbA1c decreased throughout the whole study. Sixty per cent of patients achieved an HbA1c level <8% after 18 months. Both men and women had similar glycaemic compensation. Men had a significantly higher risk of fatal coronary heart disease (CHD) (p < 0.001), stroke (p < 0.01) and fatal stroke (p < 0.01) compared to women. We found the risk of fatal CHD to be 38-fold higher in men compared to women (p < 0.01).

CONCLUSION

Potential cardiovascular effects of antidiabetic treatment should be clearly defined with possible different effects according to gender. We found a much higher risk in men than women, even when their glycaemic compensation was comparable.

Scientific independence and objectivity: many questions linger about treatment of type 2 diabetes, such as scientific study design, optimal glucose control and the safety of injecting exogenous insulin

Whilst clinical guidelines exist for the treatment of people with type 2 diabetes, many underlying assumptions are still not qualified by convincing evidence. In this commentary, it is argued that fundamental issues still cloud clinical practice, such as biases in the design of clinical studies, the association between glucose control & clinical outcomes, and the safety of exposure to exogenous insulin and other glucose-lowering drugs. Relevant scientific evidence and alternative opinions about important issues continue to be largely ignored, and no effort has been made to resolve these questions. This may have had serious consequences, such as stifling innovation because there are no further benefits to be achieved in relation to glucose control.

Insulin Therapy in Pregnancy Hypertensive Diseases and its Effect on the Offspring and Mother Later in Life

Pregnancy hypertensive disorders such as Preeclampsia (PE) are strongly correlated with insulin resistance, a condition in which the metabolic handling of D-glucose is deficient. In addition, the impact of preeclampsia is enhanced by other insulin-resistant disorders, including polycystic ovary syndrome and obesity. For this reason, there is a clear association between maternal insulin resistance, polycystic ovary syndrome, obesity and the development of PE. However, whether PE is a consequence or the cause of these disorders is still unclear. Insulin therapy is usually recommended to pregnant women with diabetes mellitus when dietary and lifestyle measures have failed. The advantage of insulin therapy for Gestational Diabetes Mellitus (GDM) patients with hypertension is still controversial; surprisingly, there are no studies in which insulin therapy has been used in patients with hypertension in pregnancy without or with an established GDM. This review is focused on the use of insulin therapy in hypertensive disorders in the pregnancy and its effect on offspring and mother later in life. PubMed and relevant medical databases have been screened for literature covering research in the field especially in the last 5-10 years.

The Changing Landscape of Pharmacotherapy for Diabetes Mellitus: A Review of Cardiovascular Outcomes

The prevention of cardiovascular morbidity and mortality has always been a primary concern in patients with type 2 diabetes. Modern trials of glucose-lowering therapies now assess major adverse cardiac events as an endpoint in addition to the effects on glycaemic control. Whilst the data on the efficacy of intensive glucose lowering on reducing cardiovascular risk are limited, there are now increasing numbers of glucose-lowering therapies that have proven cardiovascular benefit independent of glucose lowering. This review will summarise the available literature on cardiovascular outcomes in relation to metformin, sulphonylureas, di-peptidyl peptidase-4 inhibitors, glucagon-like peptide receptor agonists, sodium-glucose co-transporter 2 inhibitors, thiazolidinediones, acarbose and insulin. In addition, new paradigms in diabetes management and the importance of treatment selection based on considerations including but not limited to glycaemic control will be discussed.

Microporous scaffolds support assembly and differentiation of pancreatic progenitors into β-cell clusters

Human pluripotent stem cells (hPSCs) represent a promising cell source for the development of β-cells for use in therapies for type 1 diabetes. Current culture approaches provide signals to mimic a temporal control of organogenesis to drive the differentiation towards β-cells. However, spatial control may represent an opportunity to improve the efficiency and manufacturing of β-cells. Herein, we adapted the current culture systems to microporous biomaterials with the hypothesis that the pores can guide the assembly of pancreatic progenitors into clusters of defined size that can influence maturation. The scaffold culture allowed hPSC-derived pancreatic progenitors to form clusters at a consistent size as cells differentiated. By modulating the scaffold pore sizes, we observed 250-425 µm pore size scaffold cultures augmented insulin expression and key β-cell maturation markers compared to cells cultured in suspension. Furthermore, when compared to suspension cultures, the scaffold culture showed increased insulin secretion in response to glucose stimulus indicating the development of functional β-cells. In addition, scaffolds facilitated cell-cell interactions enabled by the scaffold design and supported cell-mediated matrix deposition of extracellular matrix (ECM) proteins associated with the basement membrane of islet cells. We further investigated the influence of ECM on cell development by incorporating an ECM matrix on the scaffold prior to cell seeding; however, their presence did not further enhance maturation. These results suggest the microporous scaffold culture provides a conducive environment that drives in vitro differentiation of hPSC-derived insulin-producing glucose-responsive β-cells and demonstrates the feasibility of these scaffolds as a biomanufacturing platform. STATEMENT OF SIGNIFICANCE: Cell therapy for diabetes is a promising strategy, yet generating limitless insulin-producing mature β-cells from human pluripotent stem cells (hPSCs) remains a challenge. Current hPSC differentiation methods involve media containing signals to drive maturation toward β-cells and spontaneous cluster formation. Herein, we sought to provide spatial cues to guide assembly of cells into 3D structures by culture within the pores of a microporous scaffold. The scaffolds direct cell-cell interactions within the pores and provide a support for cell-mediated matrix deposition that collectively creates a niche to promote functional hPSC-derived β-cell clusters. These scaffolds for 3D culture may contribute to hPSC differentiation methods for the generation of β-cells that can treat patients with diabetes.

Atherosclerosis is a vascular stem cell disease caused by insulin

The present article proposes the hypothesis that when multipotent vascular stem cells are exposed to excessive insulin in a rhythmic pattern of sharply rising and falling concentrations, their differentiation is misdirected toward adipogenic and osteogenic cell lineages. This results in plaque-like accumulation of adipocytes with fat and cholesterol deposition from adipocyte debris, and osteogenic (progenitor) cells with a calcified matrix in advanced lesions. The ingrowth of capillaries and infiltration with macrophages, which upon uptake of lipids turn into foam cells, are unspecific pro-resolving reactions. Epidemiological, histopathological, pharmacological, and experimental evidence in favour of this hypothesis is summarised.

The association study of high-sensitivity C-reactive protein, pentraxin 3, nitrotyrosine, and insulin dose in patients with insulin-treated type 2 diabetes mellitus

PURPOSE

The objective of this study was to examine the association between insulin dose and high-sensitivity C-reactive protein (hsCRP), nitrotyrosine, and pentraxin 3 in patients with insulin-treated type 2 diabetes.

PATIENTS AND METHODS

Eighty patients with type 2 diabetes treated with insulin for >6 months and with stable insulin doses (±10%) within 3 months before inclusion were enrolled in this study. Medical history, including use of insulin and insulin doses, concomitant diseases and medication, and anthropometric and routine biochemical parameters were collected for each patient. hsCRP, nitrotyrosine, and pentraxin 3 were measured in fasting conditions. Comparison analysis was performed according to the distribution in tertiles of insulin dose/kg of body weight, and linear regression adjusted for confounding factors was used to examine the associations between markers of inflammation, oxidative stress, and insulin dose.

RESULTS

In the comparison analysis, no statistically significant difference was found between hsCRP, nitrotyrosine, and pentraxin 3 levels across tertiles of insulin dose expressed as IU/kg of body weight (p for trend >0.05 for all comparisons) except a significantly higher hsCRP level in tertile 3 compared to tertile 1 (3.9±3.6 vs 6.1±3.8 mg/dL, p=0.035). In regression analysis, after adjustment for age, gender, smoking, body mass index, glycated hemoglobin, C-peptide, metformin, antiplatelet, and statin use, only hsCRP levels were statistically significant associated with insulin dose/kg of body weight (β=0.237, p=0.043).

CONCLUSION

In this sample of patients with type 2 diabetes treated with insulin for >6 months, hsCRP was positively associated with insulin doses. No such association was found for pentraxin 3, a more specific marker of vascular inflammation, and for nitrotyrosine as a marker of oxidative stress.

Insulin Therapy Increases Cardiovascular Risk in Type 2 Diabetes

Insulin therapy increased cardiovascular (CV) risk and mortality among type 2 diabetes (T2D) patients in several recently reported clinical outcomes trials. To assess whether this association is causative or coincidental, PubMed searches were used to query the effects of insulin therapy for T2D on CV health and longevity from large-scale outcomes trials, meta-analyses, and patient registry studies, as well as basic research on insulin's direct and pleiotropic actions. Although several old studies provided conflicting results, the majority of large observational studies show strong dose-dependent associations for injected insulin with increased CV risk and worsened mortality. Insulin clearly causes weight gain, recurrent hypoglycemia, and, other potential adverse effects, including iatrogenic hyperinsulinemia. This over-insulinization with use of injected insulin predisposes to inflammation, atherosclerosis, hypertension, dyslipidemia, heart failure (HF), and arrhythmias. These associations support the findings of large-scale evaluations that strongly suggest that insulin therapy has a poorer short- and long-term safety profile than that found to many other anti-T2D therapies. The potential adverse effects of insulin therapy should be weighed against proven CV benefits noted for select other therapies for T2D as reported in recent large randomized controlled trials.

Use of imaging and clinical data to screen for cardiovascular disease in asymptomatic diabetics

Background

There is increasing evidence to suggest that not all individuals with type 2 diabetes mellitus (T2DM) have equal risk for developing cardiovascular disease. We sought to compare the yield of testing for pre-clinical atherosclerosis with various approaches.

Methods

98 asymptomatic individuals with T2DM without known coronary artery disease (CAD) were enrolled in a prospective study and underwent carotid ultrasound, exercise treadmill testing (ETT), coronary artery calcium (CAC) scoring, and coronary computed tomography angiography (CTA).

Results

Of 98 subjects (average age 55 ± 6, 64 % female), 43 (44 %) had coronary plaque detectable on CTA, and 38 (39 %) had CAC score >0. By CTA, 16 (16 %) had coronary stenosis ≥50 %, including three subjects with CAC = 0. Subjects with coronary plaque had greater prevalence of carotid plaque (58 % vs. 38 %, p = 0.01) and greater carotid intima media thickness (0.80 ± 0.20 mm vs. 0.70 ± 0.11 mm, p = 0.02). Notably, 18 of 55 subjects (33 %) with normal CTA had carotid plaque. Eight subjects had a positive ETT, of whom five had ≥ 50 % coronary stenosis, two had <50 % stenosis, and one had no CAD. Among these tests, CAC scoring had the highest sensitivity and specificity for prediction of CAD.

Conclusion

Among asymptomatic subjects with T2DM, a majority (56 %) had no CAD by CTA. When compared to CTA, CAC was the most accurate screening modality for detection of CAD, while ETT and carotid ultrasound were less sensitive and specific. However, 33 % of subjects with normal coronary CTA had carotid plaque, suggesting that screening for carotid plaque might better characterize stroke risk in such patients.