Incretin-based medications for type 2 diabetes: an overview of reviews

Epidemiology of type 2 diabetes mellitus and treatment utilization patterns among the elderly from the first wave of Longitudinal Aging study in India (2017-18)using a Heckman selection model

INTRODUCTION

Unmanaged Type 2 diabetes mellitus (T2DM) substantially contributes to the multi-morbidity of the elderly. Fewer research has concentrated on understanding the determinants of treatment utilization among older people, with even lesser concerns about missing data in outcome variables leading to biased estimates. The present study intends to evaluate the epidemiology of T2DM in the elderly in India and explore the socioeconomic and behavioral risk factors determining the treatment utilization among the elderly > 60 years in India by addressing the missing data to generate robust estimates.

METHODS

The secondary analysis used data from the Longitudinal Ageing Study in India. The key dependent variables were the presence or absence of T2DM and treatment utilization. Descriptive statistics were used to understand the differences in the prevalence of diabetes and the utilization of treatment across various socio-demographic characteristics. Heckman's statistical technique evaluated the predictors of T2DM and treatment utilization. Analysis was done using STATA software version 14.0.

RESULTS

Almost 14% elderly reported to be living with T2DM. The odds of living with T2DM increased with non-working status, a sedentary lifestyle, and a higher BMI. A higher proportion of the elderly was on oral drugs than insulin and had been practicing lifestyle modifications to control their disease. The probability of developing T2DM was lower among females than males, but females had better odds for treatment utilization of health medication than males. Lastly, treatment utilization was significantly affected by socio-demographic characteristics like education and monthly per capita expenditure.

CONCLUSIONS

Treatment utilization by the elderly living with T2DM is significantly affected by socio-demographic characteristics. Keeping in mind the increasing proportion of the geriatric population in our country, it is pertinent to tailor-made counseling sessions for the elderly to improve medication utilization and adherence and realize our goals concerning non-communicable diseases.

Effects of air pollution on health: A mapping review of systematic reviews and meta-analyses

BACKGROUND

There has been a notable increase in knowledge production on air pollution and human health.

OBJECTIVE

To analyze the state of the art on the effects of air pollution on human health through a mapping review of existing systematic reviews and meta-analyses (SRs and MAs).

METHODS

The systematic mapping review was based on the recommendations for this type of scientific approach in environmental sciences. The search was performed using PubMed, Web of Science, Scopus, Cinahl, and Cochrane Library databases, from their inception through June 2020.

RESULTS

Among 3401 studies screened, 240 SRs and MAs satisfied the inclusion criteria. Five research questions were answered. There has been an overall progressive increase in publications since 2014. The majority of the SRs and MAs were carried out by researchers from institutions in China, the US, the UK, and Italy. Most studies performed a meta-analysis (161). In general, the reviews support the association of air pollution and health outcomes, and analyzed the effects of outdoor air pollution. The most commonly investigated health outcome type was the respiratory (mainly asthma and COPD), followed by cardiovascular outcomes (mainly stroke). Particulate matter (with a diameter of 2.5 μm (PM_2.5) and 10 μm (PM₁₀) or less) and nitrogen dioxide (NO₂) were the most widely investigated pollutants in the reviews. The general population was the most common sample in the reviews, followed by children, and adults. The majority of the reviews investigated health outcomes of respiratory diseases in children, as well as cardiovascular diseases in all ages. Combining health outcomes and air pollutants, PM_2.5 was included in a higher number of reviews in eight health outcomes, mainly cardiovascular diseases.

DISCUSSION

The majority of SRs and MAs showed that air pollution has harmful effects on health, with a focus on respiratory and cardiovascular outcomes. Future studies should extend the analysis to psychological and social aspects influenced by air pollution.

Non-Invasive Blood Glucose Monitoring Technology: A Review

In recent years, with the rise of global diabetes, a growing number of subjects are suffering from pain and infections caused by the invasive nature of mainstream commercial glucose meters. Non-invasive blood glucose monitoring technology has become an international research topic and a new method which could bring relief to a vast number of patients. This paper reviews the research progress and major challenges of non-invasive blood glucose detection technology in recent years, and divides it into three categories: optics, microwave and electrochemistry, based on the detection principle. The technology covers medical, materials, optics, electromagnetic wave, chemistry, biology, computational science and other related fields. The advantages and limitations of non-invasive and invasive technologies as well as electrochemistry and optics in non-invasives are compared horizontally in this paper. In addition, the current research achievements and limitations of non-invasive electrochemical glucose sensing systems in continuous monitoring, point-of-care and clinical settings are highlighted, so as to discuss the development tendency in future research. With the rapid development of wearable technology and transdermal biosensors, non-invasive blood glucose monitoring will become more efficient, affordable, robust, and more competitive on the market.

HNF4α is a novel regulator of intestinal glucose-dependent insulinotropic polypeptide

Mutations in the HNF4A gene cause MODY1 and are associated with an increased risk of Type 2 diabetes mellitus. On the other hand, incretins are hormones that potentiate reductions in blood glucose levels. Given the established role of incretin-based therapy to treat diabetes and metabolic disorders, we investigated a possible regulatory link between intestinal epithelial HNF4α and glucose-dependent insulinotropic polypeptide (GIP), an incretin that is specifically produced by gut enteroendocrine cells. Conditional deletion of HNF4α in the whole intestinal epithelium was achieved by crossing Villin-Cre and Hnf4α^loxP/loxP C57BL/6 mouse models. GIP expression was measured by qPCR, immunofluorescence and ELISA. Gene transcription was assessed by luciferase and electrophoretic mobility shift assays. Metabolic parameters were analyzed by indirect calorimetry and dual-energy X-ray absorptiometry. HNF4α specific deletion in the intestine led to a reduction in GIP. HNF4α was able to positively control Gip transcriptional activity in collaboration with GATA-4 transcription factor. Glucose homeostasis and glucose-stimulated insulin secretion remained unchanged in HNF4α deficient mice. Changes in GIP production in these mice did not impact nutrition or energy metabolism under normal physiology but led to a reduction of bone area and mineral content, a well described physiological consequence of GIP deficiency. Our findings point to a novel regulatory role between intestinal HNF4α and GIP with possible functional impact on bone density.

Comparative Safety of Dipeptidyl Peptidase-4 Inhibitors Versus Sulfonylureas and Other Glucose-lowering Therapies for Three Acute Outcomes

Although the glucose lowering effect of dipeptidyl peptidase-4 (DPP4) inhibitors is well established, several potential serious acute safety concerns have been raised including acute kidney injury, respiratory tract infections, and acute pancreatitis. Using the UK-based Clinical Practice Research Datalink (CPRD), we identified initiators (365-day washout period) of DPP4 inhibitors and relevant comparators including initiators of sulfonylureas, metformin, thiazolidinediones, and insulin between January 2007 and January 2016 to quantify the association between DPP4 inhibitors and three acute health events – acute kidney injury, respiratory tract infections, and acute pancreatitis. The associations between drug and study outcomes were estimated using Cox proportional hazard models adjusted for deciles of high-dimensional propensity scores and number of additional glucose lowering agents. After controlling for potential confounders, the risk was not significantly increased or decreased for initiators of DPP4 inhibitors compared to sulfonylureas (hazard ratio (HR) [95% confidence interval (CI)] for acute kidney injury: 0.81 [0.56–1.18]; HR for respiratory tract infections: 0.93 [0.84–1.04]; HR for acute pancreatitis 1.03 [0.42–2.52], metformin (HR for respiratory tract infection 0.91 [0.65–1.27]), thiazolidinediones (HR for acute kidney injury: 1.12 [0.60–2.10]; HR for respiratory tract infections: 1.02 [0.86–1.21]; HR for acute pancreatitis: 1.21 [0.25–5.72]), or insulin (HR for acute kidney injury: 1.40 [0.77–2.55]; HR for respiratory tract infections: 0.74 [0.60–0.92]; HR for acute pancreatitis: 1.01 [0.24–4.19]). Initiators of DPP4 inhibitors were associated with an increased risk of acute kidney injury when compared to metformin initiators (HR [95% CI] for acute kidney injury: 1.85 [1.10–3.12], although this association was attenuated when DPP4 inhibitor monotherapy was compared to metformin monotherapy exposure as a time-dependent variable (HR 1.39 [0.91–2.11]). Initiation of a DPP4 inhibitor was not associated with an increased risk of acute kidney injury, respiratory tract infections, or acute pancreatitis compared to sulfonylureas or other glucose-lowering therapies.

What have we learnt from "real world" data, observational studies and meta-analyses

The incretin therapies glucagon-like peptide-1 receptor agonists (GLP-1 RA) and dipeptidyl peptidase-IV (DPP-IV) inhibitors are now well-established as second and third-line therapies and in combination with insulin for the treatment of type 2 diabetes. Over the last decade, there is accumulating evidence of their efficacy and safety from both large multicentre randomized clinical trials (RCT) and observational studies. Cardiovascular outcome trials have confirmed that several of these agents are also non-inferior to placebo with the GLP-1 RA liraglutide and semaglutide recently found to be superior in terms of major adverse cardiovascular events. Observational studies and post-marketing surveillance provide real world evidence of safety and effectiveness of these agents and have provided reassurance that signals for pancreatitis and pancreatic cancer seen in clinical trials are not of major concern in large patient populations. Well-designed real world studies complement RCTs and systematic reviews but appropriate data and methodologies, which are constantly improving, are necessary to answer appropriate clinical questions relating to the use of incretin therapies.

KCNQ1 gene polymorphism is associated with glycaemic response to treatment with DPP-4 inhibitors

AIMS

Only afew gene variants were associated with the response to dipeptidylpeptidase-4 inhibitors (DPP4I). KCNQ1 gene variants were previously related both to type 2 diabetes (T2D) and incretin effect. We hypothesized that T2D related KCNQ1 variants would be associated with smaller glucose-lowering effect of DDP4I.

METHODS

We performed a retrospective study in 137 Caucasian subjects with T2D who were followed for 6months after initiation of DPP4I treatment. Genotyping for KCNQ1 rs163184 and rs151290 was performed using PCR-HRMA and PCR-RFLP methods, respectively. The main clinical outcome was reduction in HbA1c (ΔHbA1c) after 6-month DPP4I treatment.

RESULTS

KCNQ1 rs163184 T>G variant was associated with the response to DPP4I treatment in genetic additive model (β=-0.30, p=0.022). For each G allele in the rs163184 genotype, we observed a 0.3% (3.3mmol/mol) less reduction in HbA1c during treatment with a DPP4I. Both the GG homozygotes and G-allele carriers had significantly smaller HbA1c reduction in comparison with the TT homozygotes.

CONCLUSIONS

KCNQ1 rs163184 T>G variant was associated with a reduced glycaemic response to DPP4I. The difference of 0.6% (6.5mmol/mol) in HbA1c reduction between the TT and GG homozygotes might be of clinical significance if replicated in further studies.

Is It Time to Change the Type 2 Diabetes Treatment Paradigm? Yes! GLP-1 RAs Should Replace Metformin in the Type 2 Diabetes Algorithm

Most treatment guidelines, including those from the American Diabetes Association/European Association for the Study of Diabetes and the International Diabetes Federation, suggest metformin be used as the first-line therapy after diet and exercise. This recommendation is based on the considerable body of evidence that has accumulated over the last 30 years, but it is also supported on clinical grounds based on metformin's affordability and tolerability. As such, metformin is the most commonly used oral antihyperglycemic agent in the U.S. However, based on the release of newer agents over the recent past, some have suggested that the modern approach to disease management should be based upon identification of its etiology and correcting the underlying biological disturbances. That is, we should use interventions that normalize or at least ameliorate the recognized derangements in physiology that drive the clinical manifestation of disease, in this circumstance, hyperglycemia. Thus, it is argued that therapeutic interventions that target glycemia but do not correct the underlying pathogenic disturbances are unlikely to result in a sustained benefit on the disease process. In our field, there is an evolving debate regarding the suggested first step in diabetes management and a call for a new paradigm. Given the current controversy, we provide a Point-Counterpoint debate on this issue. In the point narrative below that precedes the counterpoint narrative, Drs. Abdul-Ghani and DeFronzo provide their argument that a treatment approach for type 2 diabetes based upon correcting the underlying pathophysiological abnormalities responsible for the development of hyperglycemia provides the best therapeutic strategy. Such an approach requires a change in the recommendation for first-line therapy from metformin to a GLP-1 receptor agonist. In the counterpoint narrative that follows Drs. Abdul-Ghani and DeFronzo's contribution, Dr. Inzucchi argues that, based on the medical community's extensive experience and the drug's demonstrated efficacy, safety, low cost, and cardiovascular benefits, metformin should remain the "foundation therapy" for all patients with type 2 diabetes, barring contraindications.-William T. CefaluChief Scientific, Medical & Mission Officer, American Diabetes Association.

Tolerance Does Not Develop Toward Liraglutide's Glucose-Lowering Effect

CONTEXT

Glucagon-like peptide-1 receptor agonists are popular antidiabetic drugs with potent glucose-lowering effects and low risk of hypoglycemia. Animal experiments and human data indicate that tolerance develops toward at least some of their effects (e.g., gastric motility). Whether tolerance develops toward the glucose-lowering effect of glucagon-like peptide-1 receptor agonists has never been formally tested.

OBJECTIVE

The objective of this pilot study was to test the hypothesis whether tolerance develops toward glucagon-like peptide-1 receptor agonists' glucose-lowering effect in chronic use.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

We conducted a single group, open-label clinical trial. Ten healthy volunteers were treated with 0.6 mg liraglutide once daily subcutaneously for 21 days. The drug's effect was quantified by serial graded glucose infusion tests, with glucose and c-peptide measured every 20 minutes and insulin secretion rate calculated.

MAIN OUTCOME MEASURE

The primary outcome was a change in the dose-response relationship between calculated insulin secretion rate and blood glucose level after acute and chronic administration of liraglutide.

RESULTS

Liraglutide clearly decreased the glucose values during the graded glucose infusion test and robustly enhanced insulin secretion. For all parameters, chronic liraglutide was as effective as acute treatment in human subjects.

CONCLUSIONS

We conclude that our results largely refute the hypothesis of tolerance development with prolonged liraglutide use in healthy nonobese humans.

Impact of ambient temperature on morbidity and mortality: An overview of reviews

The objectives were (i) to conduct an overview of systematic reviews to summarize evidence from and evaluate the methodological quality of systematic reviews assessing the impact of ambient temperature on morbidity and mortality; and (ii) to reanalyse meta-analyses of cold-induced cardiovascular morbidity in different age groups. The registration number is PROSPERO-CRD42016047179. PubMed, Embase, the Cochrane Library, Web of Science, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Global Health were systematically searched to identify systematic reviews. Two reviewers independently selected studies for inclusion, extracted data, and assessed quality. The Assessment of Multiple Systematic Reviews (AMSTAR) checklist was used to assess the methodological quality of included systematic reviews. Estimates of morbidity and mortality risk in association with heat exposure, cold exposure, heatwaves, cold spells and diurnal temperature ranges (DTRs) were the primary outcomes. Twenty-eight systematic reviews were included in the overview of systematic reviews. (i) The median (interquartile range) AMSTAR scores were 7 (1.75) for quantitative reviews and 3.5 (1.75) for qualitative reviews. (ii) Heat exposure was identified to be associated with increased risk of cardiovascular, cerebrovascular and respiratory mortality, but was not found to have an impact on cardiovascular or cerebrovascular morbidity. (iii) Reanalysis of the meta-analyses indicated that cold-induced cardiovascular morbidity increased in youth and middle-age (RR=1.009, 95% CI: 1.004-1.015) as well as the elderly (RR=1.013, 95% CI: 1.007-1.018). (iv) The definitions of temperature exposure adopted by different studies included various temperature indicators and thresholds. In conclusion, heat exposure seemed to have an adverse effect on mortality and cold-induced cardiovascular morbidity increased in the elderly. Developing definitions of temperature exposure at the regional level may contribute to more accurate evaluations of the health effects of temperature.

Type 2 Diabetes in the Elderly: Challenges in a Unique Patient Population

In the older patient population, rates of Type 2 Diabetes (T2D) and obesity are reaching epidemic proportions. In fact, older patients will soon constitute the majority of patients with T2D in most developed countries. The higher prevalence of T2D in older individuals is seen in both men and women and across racial and ethnic groups. However, certain ethnic groups are disproportionately affected and successful strategies must account for these fundamental differences. T2D in old age is associated with traditional diabetes-associated complications including micro- and macro vascular disease, but is also closely related to numerous other comorbidities including cognitive impairment, urinary incontinence, sarcopenia, and increased fall risk. An overall state of chronic inflammation and dysregulated immune system may underlie these increased risks; yet our understanding of immunometabolism during the aging process remains incomplete. In addition, optimal recognition and treatment of diabetes in the elderly is hampered by a lack of relevant, high-quality studies, as the majority of clinical trial data establishing risk profiles, glycemic targets, and therapeutic interventions for T2D are not applicable for large segments of the older patient population. Simply acknowledging this gap is inadequate. We need strong evidence-based data upon which to successfully identify diabetic patients and then intervene in ways that are targeted to specific individuals within a heterogeneous group of elderly patients with T2D.

GPR142 Controls Tryptophan-Induced Insulin and Incretin Hormone Secretion to Improve Glucose Metabolism

GPR142, a putative amino acid receptor, is expressed in pancreatic islets and the gastrointestinal tract, but the ligand affinity and physiological role of this receptor remain obscure. In this study, we show that in addition to L-Tryptophan, GPR142 signaling is also activated by L-Phenylalanine but not by other naturally occurring amino acids. Furthermore, we show that Tryptophan and a synthetic GPR142 agonist increase insulin and incretin hormones and improve glucose disposal in mice in a GPR142-dependent manner. In contrast, Phenylalanine improves in vivo glucose disposal independently of GPR142. Noteworthy, refeeding-induced elevations in insulin and glucose-dependent insulinotropic polypeptide are blunted in Gpr142 null mice. In conclusion, these findings demonstrate GPR142 is a Tryptophan receptor critically required for insulin and incretin hormone regulation and suggest GPR142 agonists may be effective therapies that leverage amino acid sensing pathways for the treatment of type 2 diabetes.

Comparative effectiveness of incretin-based therapies and the risk of death and cardiovascular events in 38,233 metformin monotherapy users

There is limited comparative effectiveness evidence to guide approaches to managing diabetes in individuals failing metformin monotherapy. Our aim was to compare the incidence of all-cause mortality and major adverse cardiovascular events (MACEs) among new metformin monotherapy users initiating a dipeptidyl-peptidase-4 inhibitor (DPP4i), glucagon-like peptide-1 receptor agonist (GLP-1RA), sulfonylurea (SU), thiazolidinedione, or insulin.We conducted a cohort study using the UK-based Clinical Practice Research Datalink. Participants included a cohort of 38,233 new users of metformin monotherapy who initiated a 2nd antidiabetic agent between January 1, 2007 and December 31, 2012 with follow-up until death, disenrollment, therapy discontinuation, or study end-date. A subcohort of 21,848 patients with linked hospital episode statistics (HES) and Office of National Statistics (ONS) data were studied to include MACE and cardiovascular-related death. The primary exposure contrasts, defined a priori, were initiation of a DPP4i versus an SU and initiation of a GLP-1RA versus an SU following metformin monotherapy. Cox proportional hazards models were used to assess the relative differences in time to mortality and MACE between exposure contrasts, adjusting for important baseline patient factors and comedications used during follow-up.The main study cohort consisted of 6213 (16%) patients who initiated a DPP4i, 25,916 initiated an SU (68%), 4437 (12%) initiated a TZD, 487 (1%) initiated a GLP-1RA, 804 (2%) initiated insulin, and 376 (1%) initiated a miscellaneous agent as their 2nd antidiabetic agent. Mean age was 62 years, 59% were male, and mean glycated hemoglobin was 8.8% (92.6 mmol/mol). Median follow-up was 2.7 years (interquartile range 1.3-4.2). Mortality rates were 8.2 deaths/1000 person-years for DPP4i and 19.1 deaths/1000 person-years for SU initiators. Adjusted hazards ratio (aHR) for mortality in DPP4i versus SU initiators = 0.58, 95% CI 0.46 to 0.73, P < 0.001. MACE rates were 19.1/1000 person-years for DPP4i initiators, 15.9/1000 person-years for GLP1-RA initiators versus 33.1/1000 person-years for SU initiators (aHR: DPP4i vs SU initiators = 0.64, 95%CI 0.52-0.80; GLP1RA vs SU initiators = 0.73, 95% CI 0.34-1.55).In this cohort of metformin monotherapy users, 2nd-line DPP4i use was associated with a 42% relative reduction in all-cause mortality and 36% reduction in MACE versus SUs, the most common 2nd-line therapy in our study. GLP-1RAs were not associated with adverse events in this cohort.

GPR119 Agonist AS1269574 Activates TRPA1 Cation Channels to Stimulate GLP-1 Secretion

GPR119 is a G protein-coupled receptor expressed on intestinal L cells that synthesize and secrete the blood glucose-lowering hormone glucagon-like peptide-1 (GLP-1). GPR119 agonists stimulate the release of GLP-1 from L cells, and for this reason there is interest in their potential use as a new treatment for type 2 diabetes mellitus. AS1269574 is one such GPR119 agonist, and it is the prototype of a series of 2,4,6 trisubstituted pyrimidines that exert positive glucoregulatory actions in mice. Here we report the unexpected finding that AS1269574 stimulates GLP-1 release from the STC-1 intestinal cell line by directly promoting Ca(2+) influx through transient receptor potential ankyrin 1 (TRPA1) cation channels. These GPR119-independent actions of AS1269574 are inhibited by TRPA1 channel blockers (AP-18, A967079, HC030031) and are not secondary to intracellular Ca(2+) release or cAMP production. Patch clamp studies reveal that AS1269574 activates an outwardly rectifying membrane current with properties expected of TRPA1 channels. However, the TRPA1 channel-mediated action of AS1269574 to increase intracellular free calcium concentration is not replicated by GPR119 agonists (AR231453, oleoylethanolamide) unrelated in structure to AS1269574. Using human embryonic kidney-293 cells expressing recombinant rat TRPA1 channels but not GPR119, direct TRPA1 channel activating properties of AS1269574 are validated. Because we find that AS1269574 also acts in a conventional GPR119-mediated manner to stimulate proglucagon gene promoter activity in the GLUTag intestinal L cell line, new findings reported here reveal the surprising capacity of AS1269574 to act as a dual agonist at two molecular targets (GPR119/TRPA1) important to the control of L-cell function and type 2 diabetes mellitus drug discovery research.

Diabetes in Asians

The prevalence of diabetes is increasing globally, particularly in Asia. According to the 2013 Diabetes Atlas, an estimated 366 million people are affected by diabetes worldwide; 36% of those affected live in the Western Pacific region, with a significant proportion in East Asia. The reasons for this marked increase in the prevalence of diabetes can be extrapolated from several distinct features of the Asian region. First, the two most populated countries, China and India, are located in Asia. Second, Asians have experienced extremely rapid economic growth, including rapid changes in dietary patterns, during the past decades. As a result, Asians tend to have more visceral fat within the same body mass index range compared with Westerners. In addition, increased insulin resistance relative to reduced insulin secretory function is another important feature of Asian individuals with diabetes. Young age of disease onset is also a distinctive characteristic of these patients. Moreover, changing dietary patterns, such as increased consumption of white rice and processed red meat, contributes to the deteriorated lifestyle of this region. Recent studies suggest a distinctive responsiveness to novel anti-diabetic agents in Asia; however, further research and efforts to reverse the increasing prevalence of diabetes are needed worldwide.