Failure of monotherapy in clinical practice in patients with type 2 diabetes: The Korean National Diabetes Program

Metformin for the Treatment of Type 2 Diabetes in Asian Adults: A Systematic Review

Metformin is a cheap, orally administered, guideline recommended glucose-lowering drug (GLD), initiated as monotherapy in treatment naïve newly diagnosed type 2 diabetes (T2D), and in combination with other GLDs in T2D not controlled on metformin. The unique Asian T2D phenotype that is markedly different than Western population, and warrants T2D treatment approaches unique to the Asian population. However, the bulk of metformin literature is from Western population and may not be generalizable for Asians. The systematic review evaluated the efficacy and safety of metformin monotherapy and combination therapy in Asians. Literature on other GLDs recommended by the 2023 American Diabetes Association guidelines as add-on therapy to metformin were included from Asia. The systematic review concluded that metformin is effective and safe for long-term T2D control of T2D in Asians. Metformin monotherapy may be initiated and continued in treatment naïve Asian patients with T2D and/or obesity if the monotherapy is adequate for achieving glycemic control. Other GLDs may be added for better glycemic control for those who fail on monotherapy. Patients inadequately controlled on another first-line GLD can achieve glycemic control and target HbA1c of <7% by adding metformin in a once daily dose. The use of metformin reduces the risk of hypoglycemia, and its gastrointestinal side effects are mild and manageable in Asians.

A Review on Affordable Combinations in Type 2 Diabetes Care: Exploring the Cost-Effective Potential of Glipizide + Metformin and Glimepiride + Metformin + Pioglitazone

Management of type 2 diabetes mellitus (T2DM) largely relies on medication adherence of individuals with diabetes to achieve optimal glycemic control. The economic burden of diabetes could impede adherence, leading to a reduction in treatment efficacy and increased risk of complications. Furthermore, monotherapy in diabetes is losing traction due to its ineffectiveness in achieving early and sustained optimal glycemic control in a significant proportion of the population. Hence, clinicians prefer combination treatment due to their improved efficacy and safety. Considering these factors, the current review highlights the safety and efficacy of the affordable combination therapies, a dual therapy, glipizide + metformin, and a triple-drug combination of glimepiride + metformin + pioglitazone and its applicability in the management of T2DM among individuals with diabetes in India.

Momordica charantia fruit reduces plasma fructosamine whereas stems and leaves increase plasma insulin in adult mildly diabetic obese Göttingen Minipigs

BACKGROUND

Traditionally Momordica charantia (Bitter gourd) is known for its blood glucose lowering potential. This has been validated by many previous studies based on rodent models but human trials are less convincing and the physiological mechanisms underlying the bioactivity of Bitter gourd are still unclear. The present study compared the effects of whole fruit or stems-leaves from five different Bitter gourd cultivars on metabolic control in adult diabetic obese Göttingen Minipigs.

METHODS

Twenty streptozotocin-induced diabetic (D) obese Minipigs (body weight ~85 kg) were subdivided in mildly and overtly D pigs and fed 500 g of obesogenic diet per day for a period of three weeks, supplemented with 20 g dried powdered Bitter gourd or 20 g dried powdered grass as isoenergetic control in a cross-over, within-subject design.

RESULTS

Bitter gourd fruit from the cultivars "Palee" and "Good healthy" reduced plasma fructosamine concentrations in all pigs combined (from 450±48 to 423±53 and 490±50 to 404±48 μmol/L, both p<0.03, respectively) indicating improved glycemic control by 6% and 17%. These effects were statistically confirmed in mildly D pigs but not in overtly D pigs. In mildly D pigs, the other three cultivars of fruit showed consistent numerical but no significant improvements in glycemic control. The composition of Bitter gourd fruit was studied by metabolomics profiling and analysis identified three metabolites from the class of triterpenoids (Xuedanoside H, Acutoside A, Karaviloside IX) that were increased in the cultivars "Palee" (>3.9-fold) and "Good healthy" (>8.9-fold) compared to the mean of the other three cultivars. Bitter gourd stems and leaves from the cultivar "Bilai" increased plasma insulin concentrations in all pigs combined by 28% (from 53±6 to 67±9 pmol/L, p<0.03). The other two cultivars of stems and leaves showed consistent numerical but no significant increases in plasma insulin concentrations. The effects on plasma insulin concentrations were confirmed in mildly D pigs but not in overtly D pigs.

CONCLUSIONS

Fruits of Bitter gourd improve glycemic control and stems-leaves of Bitter gourd increase plasma insulin concentrations in an obese pig model for mild diabetes. The effects of Bitter gourd fruit on glycemic control seem consistent but relatively small and cultivar specific which may explain the varying results of human trials reported in the literature.

Gut microbiome encoded purine and amino acid pathways present prospective biomarkers for predicting metformin therapy efficacy in newly diagnosed T2D patients

Metformin is widely used for treating type 2 diabetes mellitus (T2D). However, the efficacy of metformin monotherapy is highly variable within the human population. Understanding the potential indirect or synergistic effects of metformin on gut microbiota composition and encoded functions could potentially offer new insights into predicting treatment efficacy and designing more personalized treatments in the future. We combined targeted metabolomics and metagenomic profiling of gut microbiomes in newly diagnosed T2D patients before and after metformin therapy to identify potential pre-treatment biomarkers and functional signatures for metformin efficacy and induced changes in metformin therapy responders. Our sequencing data were largely corroborated by our metabolic profiling and identified that pre-treatment enrichment of gut microbial functions encoding purine degradation and glutamate biosynthesis was associated with good therapy response. Furthermore, we identified changes in glutamine-associated amino acid (arginine, ornithine, putrescine) metabolism that characterize differences in metformin efficacy before and after the therapy. Moreover, metformin Responders' microbiota displayed a shifted balance between bacterial lipidA synthesis and degradation as well as alterations in glutamate-dependent metabolism of N-acetyl-galactosamine and its derivatives (e.g. CMP-pseudaminate) which suggest potential modulation of bacterial cell walls and human gut barrier, thus mediating changes in microbiome composition. Together, our data suggest that glutamine and associated amino acid metabolism as well as purine degradation products may potentially condition metformin activity via its multiple effects on microbiome functional composition and therefore serve as important biomarkers for predicting metformin efficacy.

Monogenic diabetes due to an INSR mutation in a child with severe insulin resistance

SUMMARY

We report a case of an 11-year-old girl presenting with a new diagnosis of diabetes associated with a heterozygous missense mutation in the insulin receptor (INSR) gene. This case highlights that INSR gene variants can be a cause for monogenic diabetes in children and adolescents and the need for genetic evaluation in atypical presentations of diabetes. We also describe the possible role of metformin in treating individuals with type A insulin resistance syndrome due to INSR gene variants.

LEARNING POINTS

Insulin receptor (INSR) gene variants can be a cause of monogenic diabetes in children and adolescents. Genetic evaluation should be considered in children and adolescents with type 2 diabetes (T2D), particularly where there is an atypical presentation and/or positive family history. Metformin may have a role in the treatment of type A insulin resistance syndrome due to heterozygous mutation of the INSR gene.

Metabolomic Approaches to Investigate the Effect of Metformin: An Overview

Metformin is the first-line antidiabetic drug that is widely used in the treatment of type 2 diabetes mellitus (T2DM). Even though the various therapeutic potential of metformin treatment has been reported, as well as the improvement of insulin sensitivity and glucose homeostasis, the mechanisms underlying those benefits are still not fully understood. In order to explain the beneficial effects on metformin treatment, various metabolomics analyses have been applied to investigate the metabolic alterations in response to metformin treatment, and significant systemic metabolome changes were observed in biofluid, tissues, and cells. In this review, we compare the latest metabolomic research including clinical trials, animal models, and in vitro studies comprehensively to understand the overall changes of metabolome on metformin treatment.

Pharmacokinetic/Pharmacodynamic Interaction Between Evogliptin and Pioglitazone in Healthy Male Subjects

Aim

Evogliptin is a newly developed oral glucose-lowering medication of the dipeptidyl peptidase 4 (DPP-4) inhibitor class for type 2 diabetes mellitus. The combination of a DPP-4 inhibitor with pioglitazone is a promising therapeutic option. The aim of the present study was to evaluate the pharmacokinetic and pharmacodynamic interaction between evogliptin and pioglitazone.

Materials and Methods

A randomized, open-label, multiple-dose, three-treatment, three-period, six-sequence crossover study was conducted in healthy Korean male subjects. All subjects received evogliptin 5 mg once daily for 7 days (EVO), pioglitazone 30 mg once daily for 7 days (PIO) and co-administration of evogliptin 5 mg and pioglitazone 30 mg once daily for 7 days (EVO+PIO) according to the assigned sequence and period. Serial blood samples were collected for 24 hours for pharmacokinetic analysis and 3 hours after the oral glucose tolerance test for the pharmacodynamic analysis.

Results

Thirty-four subjects completed the study. EVO+PIO and EVO showed a similar maximum plasma concentration at steady state (C_max,ss) and area under the concentration-time curve during the dosing interval at the steady state (AUC_τ,ss) of evogliptin, with geometric mean ratios (GMRs) (90% confidence interval (CI)) of 1.01 (0.97–1.05) and 1.01 (0.98–1.04), respectively. EVO+PIO and PIO showed a similar C_max,ss and AUC_τ,ss of pioglitazone, with GMRs (90% CI) of 1.07 (0.99–1.17) and 1.08 (0.99–1.17), respectively. Reduction of the glucose level after EVO+PIO was larger compared to PIO and similar with EVO.

Conclusion

Concomitant administration of evogliptin and pioglitazone showed similar glucose-lowering effects with those of evogliptin alone without pharmacokinetic interactions when compared to the intake of each drug alone.

Nigella sativa and Trigonella foenum-graecum Supplemented Chapatis Safely Improve HbA1c, Body Weight, Waist Circumference, Blood Lipids, and Fatty Liver in Overweight and Diabetic Subjects: A Twelve-Week Safety and Efficacy Study

In 2019, ∼ 463 million people globally had diabetes mellitus (DM), with China (25.1%), India (16.6%), and the United States (6.69%) representing nearly 50% of that total. The primary objectives of this exploratory study were to assess the safety and potential efficacy of Nigella sativa and fenugreek seed supplemented chapatis in overweight (OW) and type 2 DM subjects. Forty subjects (15/OW; 9/DM; 16/DM/OW) consumed two chapatis twice a day 6 days/week for a daily dose of 5.45 g of an N. sativa/fenugreek combination over 12 weeks with no changes in lifestyle or medications. Anthropometric, glycemic, and vascular variables were recorded at baseline and after 6 and 12 weeks. Glycated hemoglobin (HbA1c), plasma lipids, and complete metabolic profile were measured at baseline and termination. Compliance, estimated during twice-daily individual delivery of precooked chapatis, was 100%, with no significant adverse effects. At termination, body weights, body mass index, waist and hip circumferences, index of central obesity, HbA1c, fasting blood glucose, 2-h postprandial blood glucose, estimated average glucose over 12 weeks, total cholesterol (TC), non-high density lipoprotein (HDL) cholesterol, very low density lipoprotein (VLDL), and triglycerides (TG) were decreased (P < .05) over all subjects. Subjects with HbA1c ≥7.0 exhibited greater improvements in all glycemic variables than HbA1c <7.0 subjects. In addition, the decrease in HbA1c was positively correlated with decreases in (1) hepatic enzymes alkaline phosphatase (r = 0.301, P = .0067) and aspartate transaminase (r = 0.277, P = .0129), (2) systolic blood pressure (r = 0.388, P = .0004), and (3) number of diagnostic metabolic syndrome criteria exhibited per subject (r = 0.391, P = .0005), cardiovascular risk score (CRS) (r = 0.281, P = .0115), and hepatic steatosis index (HSI) (r = 0.223, P = .0467). Atherogenic and diabetogenic indexes TC/HDL, low density lipoprotein/HDL, VLDL/HDL, and TG/HDL were all decreased (P < .05). Among all subjects, improvement (P < .05) was seen in CRS (-10.7%), fatty liver index (-19.8%), lipid accumulation product (-13.8%), and HSI (-7.53%). N. sativa/fenugreek supplemented chapatis present a safe and seamless dietary modification to address cardiometabolic risk.

Necrostatin-1 Mitigates Cognitive Dysfunction in Prediabetic Rats With No Alteration in Insulin Sensitivity

Previous studies showed that 12 weeks of high-fat diet (HFD) consumption caused not only prediabetes but also cognitive decline and brain pathologies. Recently, necrostatin-1 (nec-1), a necroptosis inhibitor, showed beneficial effects in brain against stroke. However, the comparative effects of nec-1 and metformin on cognition and brain pathologies in prediabetes have not been investigated. We hypothesized that nec-1 and metformin equally attenuated cognitive decline and brain pathologies in prediabetic rats. Rats (n = 32) were fed with either normal diet (ND) or HFD for 20 weeks. At week 13, ND-fed rats were given a vehicle (n = 8) and HFD-fed rats were randomly assigned into three subgroups (n = 8/subgroup) with vehicle, nec-1, or metformin for 8 weeks. Metabolic parameters, cognitive function, brain insulin receptor function, synaptic plasticity, dendritic spine density, microglial morphology, brain mitochondrial function, Alzheimer protein, and cell death were determined. HFD-fed rats exhibited prediabetes, cognitive decline, and brain pathologies. Nec-1 and metformin equally improved cognitive function, synaptic plasticity, dendritic spine density, microglial morphology, and brain mitochondrial function and reduced hyperphosphorylated Tau and necroptosis in HFD-fed rats. Interestingly, metformin, but not nec-1, improved brain insulin sensitivity in those rats. In conclusion, necroptosis inhibition directly improved cognition in prediabetic rats without alteration in insulin sensitivity.

rs622342 in SLC22A1, CYP2C9*2 and CYP2C9*3 and Glycemic Response in Individuals with Type 2 Diabetes Mellitus Receiving Metformin/Sulfonylurea Combination Therapy: 6-Month Follow-Up Study

Background and Objective: Since the treatment outcome with oral anti-diabetics differs between individuals, the objective of this study is to evaluate the significance of rs622342 in SLC22A1, CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910) with regard to the efficacy of metformin/sulfonylurea combination therapy in individuals with type 2 diabetes mellitus (T2DM). Methods: Eighty-eight Lebanese individuals with T2DM received metformin/sulfonylurea combination therapy over 3 and 6 months. The clinical and biochemical characteristics were collected. Genotyping of rs622342 in SLC22A1, CYP2C9*2 and CYP2C9*3 was performed using hybridization probes on real-time polymerase chain reaction (PCR) instrument. Statistical analysis was performed using SPSS 22.0. Results: The levels of fasting blood sugar (FBS) and glycated hemoglobin (HbA1c) showed a statistically significant reduction over 3 and 6 months of follow-up (p < 0.001). An interaction between rs622342 in SLC22A1, CYP2C9*2 and CYP2C9*3 (p = 0.035) was found associated with reduced levels of HbA1c levels after 3 and 6 months. A significant difference between the means of HbA1c was observed among the different groups after 3 and 6 months (p = 0.004 and p < 0.001, respectively). The most beneficial group was; AA and AC, *1*3, whereas the individuals that benefited the least were CC, *1*3 at 3 and 6 months. In contrast to HbA1c, no interaction was found between the three polymorphisms to affect FBS (p = 0.581). Conclusion: The combination of metformin/sulfonylurea therapy led to the maximum glycemic control in individuals with T2DM carrying AA or AC genotypes in SLC22A1 and *1*3 in CYP2C9.

A new perspective on the biguanide, metformin therapy in type 2 diabetes and lactic acidosis

Recent topics about metformin mainly focus on clinical studies, briefly mentioning some new aspects on the mechanisms of metformin action.

Head-to-Head Comparison of the Hypoglycemic Efficacy and Safety Between Dipeptidyl Peptidase-4 Inhibitors and α-Glucosidase Inhibitors in Patients With Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials

Background: The α-glucosidase inhibitors (AGIs) are commonly prescribed in Asian patients with type 2 diabetes mellitus (T2DM), but with a high incidence of gastrointestinal side effects. This study was aimed to compare the efficacy and safety of dipeptidyl peptidase-4 (DPP4) inhibitors and AGIs in T2DM patients in a meta-analysis.

Methods: Randomized controlled trials were identified via systematic search of PubMed, Embase, and Cochrane’s Library databases from inception to February, 2019. Meta-analyses were performed via a random or a fixed effect model according to the heterogeneity.

Results: Eighteen studies with a total of 4,051 patients with T2DM were included. The DPP4 inhibitors were associated with lower reduction of glycosylated hemoglobin (HbA1c) as compared with AGIs [weighed mean difference (WMD): −0.37%, p < 0.001]. Subgroup analyses indicated that the benefit of DPP4 inhibitors as compared with AGIs on HbA1c were independent of study design, scale, baseline HbA1c, with or without concurrent medications, or follow-up durations. Moreover, compared to AGIs, DPP4 inhibitors was associated with lower reductions of fasting blood glucose (WMD: −0.53 mmol/L, P < 0.001) and postprandial glucose at 2h (WMD: −0.60 mmol/L, P = 0.04), moderately increased body weight (WMD: 0.34 kg, P = 0.02), and decreased risk of gastrointestinal adverse events [risk ratio (RR): 0.48, P < 0.001], but unaffected risk of symptomatic hypoglycemia (RR: 0.96, P = 0.90).

Conclusions: The DPP4 inhibitors are superior to AGIs in T2DM patients for better glycemic control and lower risks of gastrointestinal side effects.