The Role of Metformin Response in Lipid Metabolism in Patients with Recent-Onset Type 2 Diabetes: HbA1c Level as a Criterion for Designating Patients as Responders or Nonresponders to Metformin

Effects of metformin on the glucose regulation, lipid levels and gut microbiota in high-fat diet with streptozotocin induced type 2 diabetes mellitus rats

OBJECTIVE

Metformin, an anti-diabetic drug, regulates blood glucose by affecting gut microbiotas. However, the potential mechanism underlying this effect remains unclear. This study aimed to evaluate the effect of metformin on glucose regulation, lipid levels, and the gut microbiota in rats with type 2 diabetes mellitus induced by a high-fat diet with streptozotocin.

RESEARCH DESIGN METHODS

Thirty Wistar rats was using in this experiment. T2DM rats were administered 300 mg/kg metformin for 8 weeks. The glucose regulation, lipid levels, organ coefficients, and gut microbiotawere measured by 16S rDNA.

RESULT

The metformin-gavaged rats exhibited significant improvements in blood glucose and serum lipid levels, accompanied by alterations in short-chain fatty acid levels and the intestinal microbiota (p < 0.05). In the diabetic rats, metformin potentially increased specific probiotics, thus improving the hypoglycaemic effects of the oral anti-diabetic drug. Further, damage to the liver and kidney was effectively alleviated in the metformin-gavaged rats.

CONCLUSION

This study's findings demonstrate that metformin exerts a positive anti-diabetic effect in HFD- and STZ-induced T2DM rats. These findings potentially provide a basis for the recommended use of metformin as a reliable oral drug for T2DM owing to its positive effect on the intestinal microbiota.

Lipidomics Profiling of Metformin-Induced Changes in Obesity and Type 2 Diabetes Mellitus: Insights and Biomarker Potential

Metformin is the first-line oral medication for treating type 2 diabetes mellitus (T2DM). In the current study, an untargeted lipidomic analytical approach was used to investigate the alterations in the serum lipidome of a cohort of 89 participants, including healthy lean controls and obese diabetic patients, and to examine the alterations associated with metformin administration. A total of 115 lipid molecules were significantly dysregulated (64 up-regulated and 51 down-regulated) in the obese compared to lean controls. However, the levels of 224 lipid molecules were significantly dysregulated (125 up-regulated and 99 down-regulated) in obese diabetic patients compared to the obese group. Metformin administration in obese diabetic patients was associated with significant dysregulation of 54 lipid molecule levels (20 up-regulated and 34 down-regulated). Levels of six molecules belonging to five lipid subclasses were simultaneously dysregulated by the effects of obesity, T2DM, and metformin. These include two putatively annotated triacylglycerols (TGs), one plasmenyl phosphatidylcholine (PC), one phosphatidylglycerol (PGs), one sterol lipid (ST), and one Mannosyl-phosphoinositol ceramide (MIPC). This study provides new insights into our understanding of the lipidomics alterations associated with obesity, T2DM, and metformin and offers a new platform for potential biomarkers for the progression of diabetes and treatment response in obese patients.

Metformin Reduces the Progression of Atherogenesis by Regulating the Sestrin2-mTOR Pathway in Obese and Diabetic Rats

Objective

In previous research, we found that Sestrin2 has a strong association with plasma atherogenicity and combats the progression of atherogenesis by regulating the AMPK-mTOR pathway. Metformin, an activator of AMPK, is widely used as a first-line therapy for diabetes, but its role in preventing atherosclerosis and cardiac outcomes is unclear. Hence, we aimed to assess the effect of metformin on preventing atherosclerosis and its regulatory role in the Sestrin2-AMPK -mTOR pathway in obese/diabetic rats.

Methods

Animals were fed a high-fat diet to induce obesity, administered streptozotocin to induce diabetes, and then treated with metformin (150 mg/kg body weight) for 14 weeks. Aorta and heart tissues were analyzed for Sestrin2 status by western blotting and immunohistochemistry, AMPK and mTOR activities were investigated using western blotting, and atherogenicity-related events were evaluated using reverse transcription quantitative polymerase chain reaction and histology.

Results

Obese and diabetic rats showed significant decrease in Sestrin2 levels and AMPK activity, accompanied by increased mTOR activity in the heart and aorta tissues. Metformin treatment significantly restored Sestrin2 and AMPK levels, reduced mTOR activity, and restored the altered expression of inflammatory markers and adhesion molecules in obese and diabetic rats to normal levels. A histological analysis of samples from obese and diabetic rats showed atherosclerotic lesions both in aorta and heart tissues. The metformin-treated rats showed a decrease in atherosclerotic lesions, cardiac hypertrophy, and cardiomyocyte degeneration.

Conclusion

This study presents further insights into the beneficial effects of metformin and its protective role against atherosclerosis through regulation of the Sestrin2-AMPK-mTOR pathway.

Lipids Alterations Associated with Metformin in Healthy Subjects: An Investigation Using Mass Spectrometry Shotgun Approach

Metformin is an orally effective insulin-sensitizing drug widely prescribed for treating type 2 diabetes mellitus (T2DM). Metformin has been reported to alter lipid metabolism. However, the molecular mechanisms behind its impact on lipid metabolism remain partially explored and understood. In the current study, mass spectrometry-based lipid profiling was used to investigate the lipidomic changes in the serum of 26 healthy individuals after a single-dose intake of metformin. Samples were analyzed at five-time points: preadministration, before the maximum concentration of metformin (Cmax), Cmax, after Cmax, and 36 h post-administration. A total of 762 molecules were significantly altered between the five-time points. Based on a comparison between baseline level and Cmax, metformin significantly increased and decreased the level of 33 and 192 lipids, respectively (FDR ≤ 0.05 and fold change cutoff of 1.5). The altered lipids are mainly involved in arachidonic acid metabolism, steroid hormone biosynthesis, and glycerophospholipid metabolism. Furthermore, several lipids acted in an opposed or similar manner to metformin levels and included fatty acyls, sterol lipids, glycerolipids, and glycerophospholipids. The significantly altered lipid species pointed to fundamental lipid signaling pathways that could be linked to the pleiotropic effects of metformin in T2DM, insulin resistance, polycystic ovary syndrome, cancer, and cardiovascular diseases.

The influence of SLC22A3 rs543159 and rs1317652 genetic variants on metformin therapeutic efficacy in newly diagnosed patients with type 2 diabetes mellitus: 25 weeks follow-up study

BACKGROUND AND AIMS

Among anti-diabetic medications, metformin has been proven to be the preferred initial pharmacologic agent for type 2 diabetes mellitus (T2DM) treatment. Despite its safety and efficacy, the response to metformin varies between individuals. Genetic variations, especially within genes involved in pharmacokinetics and pharmacodynamics of metformin (e.g SLC22A3), have been suggested to be responsible for the observed inter-individual differences. By considering the undeniable role of organic cation transporter 3 in hepatic uptake of metformin, this study was aimed to investigate the association of rs543159 and rs1317652 variants in SLC22A3 gene with response to metformin monotherapy in newly diagnosed patients with T2DM.

METHODS

The study included 200 T2DM patients who received metformin monotherapy for 25 weeks. The patients were classified into 2 groups according to their HbA1c values: the responders (reduction in HbA1c levels by at least 1% after 25 weeks treatment with metformin) and non-responders (less than 1% reduction in HbA1c levels after 25 weeks treatment with metformin). We used tetra ARMS-PCR method to determine genotypes of the target variants.

RESULTS

For the rs543159, CA and AA genotypes were more frequent in responders as compared to non-responders (OR = 2.48; 95% CI = 1.28-4.78, P-value = 0.0057) under the dominant model. In case of rs1317652 CC and CT genotypes were more frequent in metformin responders as compared to non-responder group (OR = 2.49; 95% CI = 1.32-4.70, P-value = 0.0043) under the dominant model. Parameters such as fasting blood sugar (FBS), HbA1c, and total cholesterol (TC) levels were significantly lower in the responder group after 25 weeks of metformin monotherapy. Moreover, according to the result of multiple linear regression rs543159 and base line HbA1c values are significantly associated with response to metformin monotherapy.

CONCLUSION

Our results suggested that rs543159 and rs1317652 in SLC22A3 gene might be associated with variability in response to metformin therapy in T2DM patients.

Metformin intervention ameliorates AS in ApoE-/- mice through restoring gut dysbiosis and anti-inflammation

Atherosclerosis (AS) is closely associated with chronic low-grade inflammation and gut dysbiosis. Metformin (MET) presents pleiotropic benefits in the control of chronic metabolic diseases, but the impacts of MET intervention on gut microbiota and inflammation in AS remain largely unclear. In this study, ApoE-/- mice with a high-fat diet (HFD) were adopted to assess the MET treatment. After 12 weeks of MET intervention (100mg·kg-1·d-1), relevant indications were investigated. As indicated by the pathological measurements, the atherosclerotic lesion was alleviated with MET intervention. Moreover, parameters in AS including body weights (BWs), low-density lipoprotein (LDL), triglyceride (TG), total cholesterol (TC) and malondialdehyde (MDA) were elevated; whereas high-density lipoprotein (HDL) and total superoxide dismutase (T-SOD) levels were decreased, which could be reversed by MET intervention. Elevated pro-inflammatory interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and lipopolysaccaride (LPS) in AS were decreased after MET administration. However, anti-inflammatory IL-10 showed no significant difference between AS group and AS+MET group. Consistently, accumulated macrophages in the aorta of AS were conversely lowered with MET treatment. The results of 16S rRNA sequencing and analysis displayed that the overall community of gut microbiota in AS was notably changed with MET treatment mainly through decreasing Firmicutes, Proteobacteria, Romboutsia, Firmicutes/Bacteroidetes, as well as increasing Akkermansia, Bacteroidetes, Bifidobacterium. Additionally, we found that microbiota-derived short-chain fatty acids (SCFAs) including acetic acid, propionic acid, butyric acid and valeric acid in AS were decreased, which were significantly up-regulated with MET intervention. Consistent with the attenuation of MET on gut dysbiosis, decreased intestinal tight junction protein zonula occludens-1 (ZO)-1 in AS was restored after MET supplementation. Correlation analysis showed close relationships among gut bacteria, microbial metabolites SCFAs and inflammation. Collectively, MET intervention ameliorates AS in ApoE-/- mice through restoring gut dysbiosis and anti-inflammation, thus can potentially serve as an inexpensive and effective intervention for the control of the atherosclerotic cardiovascular disease.

Identifying Glycemic Variability in Diabetes Patient Cohorts and Evaluating Disease Outcomes

Glycemic variability (GV) is an obstacle to effective blood glucose control and an autonomous risk factor for diabetes complications. We, therefore, explored sample data of patients with diabetes mellitus who maintained better amplitude of glycemic fluctuations and compared their disease outcomes with groups having poor control. A retrospective study was conducted using electronic data of patients having hemoglobin A1C (HbA1c) values with five recent time points from Think Whole Person Healthcare (TWPH). The control variability grid analysis (CVGA) plot and coefficient of variability (CV) were used to identify and cluster glycemic fluctuation. We selected important variables using LASSO. Chi-Square, Fisher’s exact test, Bonferroni chi-Square adjusted residual analysis, and multivariate Kruskal–Wallis tests were used to evaluate eventual disease outcomes. Patients with very high CV were strongly associated (p < 0.05) with disorders of lipoprotein (p = 0.0014), fluid, electrolyte, and acid–base balance (p = 0.0032), while those with low CV were statistically significant for factors influencing health status such as screening for other disorders (p = 0.0137), long-term (current) drug therapy (p = 0.0019), and screening for malignant neoplasms (p = 0.0072). Reducing glycemic variability may balance alterations in electrolytes and reduce differences in lipid profiles, which may assist in strategies for managing patients with diabetes mellitus.

Gender dependent differences in lipid metabolism in individuals with type 2 diabetes mellitus

Aim

The present study investigates gender dependent effects of insulin resistance on lipid profile and adipocytokines in individuals with diabetes receiving oral antidiabetic drugs (OADs). The aim was also to reveal the changes in the expression of genes involved in lipid metabolism and inflammation.

Methods

Lipid profile, adipocytokine levels and homeostatic model assessment of insulin resistance (HOMA-IR) was assessed in 100 patients with diabetes (M = 43, F = 57) matched for age and gender with healthy individuals (M = 45, F = 55). The expression pattern of genes was analyzed by quantitative real time PCR.

Results

Males consuming metformin with other drugs exhibited a positive association between HOMA-IR and cholesterol, triglyceride and very low density lipoprotein (VLDL). Females consuming only metformin and metformin with other drugs, showed a positive association of HOMA-IR with cholesterol and a negative association with adiponectin. In males and females with diabetes, a comparable expression of peroxisome proliferator activated receptor γ (PPARγ) while higher expression of sterol regulatory element binding protein 1 (SREBP1) was observed. Expression of fatty acid synthase (FAS), long chain acyl CoA Synthetases (ACSL), malonyl-CoA-acyl carrier protein transacylase (MCAT) and nuclear factor kappa β (NFkβ) was higher in men with diabetes than healthy males. Expression of tumor necrosis factor α (TNF-α) was higher in males and females with diabetes than respective healthy genders.

Conclusion

Insulin resistance adversely affects lipid profile, adipocytokines in males with type 2 diabetes. Expression of genes involved in lipid metabolism and inflammation is found to be undesirably and differentially altered in both the genders.

Acute glycaemic management before, during and after exercise for cardiac rehabilitation participants with diabetes mellitus: a joint statement of the British and Canadian Associations of Cardiovascular Prevention and Rehabilitation, the International Council for Cardiovascular Prevention and Rehabilitation and the British Association of Sport and Exercise Sciences

Type 1 (T1) and type 2 (T2) diabetes mellitus (DM) are significant precursors and comorbidities to cardiovascular disease and prevalence of both types is still rising globally. Currently,~25% of participants (and rising) attending cardiac rehabilitation in Europe, North America and Australia have been reported to have DM (>90% have T2DM). While there is some debate over whether improving glycaemic control in those with heart disease can independently improve future cardiovascular health-related outcomes, for the individual patient whose blood glucose is well controlled, it can aid the exercise programme in being more efficacious. Good glycaemic management not only helps to mitigate the risk of acute glycaemic events during exercising, it also aids in achieving the requisite physiological and psycho-social aims of the exercise component of cardiac rehabilitation (CR). These benefits are strongly associated with effective behaviour change, including increased enjoyment, adherence and self-efficacy. It is known that CR participants with DM have lower uptake and adherence rates compared with those without DM. This expert statement provides CR practitioners with nine recommendations aimed to aid in the participant's improved blood glucose control before, during and after exercise so as to prevent the risk of glycaemic events that could mitigate their beneficial participation.

Baseline gut microbiome composition predicts metformin therapy short-term efficacy in newly diagnosed type 2 diabetes patients

Background

The study was conducted to investigate the effects of metformin treatment on the human gut microbiome’s taxonomic and functional profile in the Latvian population, and to evaluate the correlation of these changes with therapeutic efficacy and tolerance.

Methods

In this longitudinal observational study, stool samples for shotgun metagenomic sequencing-based analysis were collected in two cohorts. The first cohort included 35 healthy nondiabetic individuals (metformin dose 2x850mg/day) at three time-points during metformin administration. The second cohort was composed of 50 newly-diagnosed type 2 diabetes patients (metformin dose–determined by an endocrinologist) at two concordant times. Patients were defined as Responders if their HbA1c levels during three months of metformin therapy had decreased by ≥12.6 mmol/mol (1%), while in Non-responders HbA1c were decreased by <12.6 mmol/mol (1%).

Results

Metformin reduced the alpha diversity of microbiota in healthy controls (p = 0.02) but not in T2D patients. At the species level, reduction in the abundance of Clostridium bartlettii and Barnesiella intestinihominis, as well as an increase in the abundance of Parabacteroides distasonis and Oscillibacter unclassified overlapped between both study groups. A large number of group-specific changes in taxonomic and functional profiles was observed. We identified an increased abundance of Prevotella copri (FDR = 0.01) in the Non-Responders subgroup, and enrichment of Enterococcus faecium, Lactococcus lactis, Odoribacter, and Dialister at baseline in the Responders group. Various taxonomic units were associated with the observed incidence of side effects in both cohorts.

Conclusions

Metformin effects are different in T2D patients and healthy individuals. Therapy induced changes in the composition of gut microbiome revealed possible mediators of observed short-term therapeutic effects. The baseline composition of the gut microbiome may influence metformin therapy efficacy and tolerance in T2D patients and could be used as a powerful prediction tool.

Glimepiride and Metformin Combinations in Diabetes Comorbidities and Complications: Real-World Evidence

Objective To evaluate the usage of various strengths of glimepiride and metformin fixed-dose combinations in the management of type 2 diabetes mellitus (T2DM) patients with comorbidities and complications. Methods A retrospective, non-randomized, non-comparative, multi-centric real-world study included T2DM patients (age > 18 years) taking glimepiride and metformin fixed-dose combinations. Age, duration of diabetes, diabetes complications, comorbidities (hypertension and dyslipidemia), dosage frequency, and concomitant medications were analyzed from medical charts. Results A total of 4858 T2DM patients were included, with a mean age of 52.67 years and males being predominant in the study population (60.85%). The laboratory investigations showed a mean glycated hemoglobin (HbA1c) of 7.5, low-density lipoprotein (LDL) cholesterol of 104.81 ± 38.19 mg/dL, and serum creatinine of 0.88 ± 0.26 mg/dL. Around 2055 (42.30%) T2DM patients were hypertensive, and telmisartan alone and a telmisartan-based combination were the drugs of choice for hypertension management. Similarly, 1073 (22.08%) T2DM patients were having dyslipidemia and were primarily managed with rosuvastatin and its combination in 664 (62%) patients. Macrovascular complications were observed in 339 (6.97%) T2DM patients, among which coronary artery disease (CAD) had maximum prevalence, affecting 273 (5.61%) T2DM patients. Microvascular complications were 1010 (20.79%) T2DM patients, among which neuropathy had affected a maximum of 686 (14.12%) followed by retinopathy (2.34%) and nephropathy (1.81%). Among the available 11 strengths, the glimepiride 2 mg and metformin 500 mg combination were most widely prescribed in 1297 (26.69%), followed by glimepiride 1 mg and metformin 500 mg in 1193 (24.57%) patients, and the preferred dosage pattern was twice a daily in 2665 (54.85%) T2DM patients. An age-wise prescription analysis showed that glimepiride and metformin combinations were the preferred choice for the management of diabetes across all the age groups. Conclusion The real-world evidence in the Indian clinical setting indicates that glimepiride and metformin fixed-dose combinations are widely used in the management in T2DM patients with comorbidities like hypertension, dyslipidemia, and diabetes complications. Glimepiride and metformin fixed-dose combinations are suitable for early as well as long-standing diabetes.

Organic Cation Transporters in Health and Disease

The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.

Whole-blood transcriptome profiling reveals signatures of metformin and its therapeutic response

Metformin, a biguanide agent, is the first-line treatment for type 2 diabetes mellitus due to its glucose-lowering effect. Despite its wide application in the treatment of multiple health conditions, the glycemic response to metformin is highly variable, emphasizing the need for reliable biomarkers. We chose the RNA-Seq-based comparative transcriptomics approach to evaluate the systemic effect of metformin and highlight potential predictive biomarkers of metformin response in drug-naïve volunteers with type 2 diabetes in vivo. The longitudinal blood-derived transcriptome analysis revealed metformin-induced differential expression of novel and previously described genes involved in cholesterol homeostasis (SLC46A1 and LRP1), cancer development (CYP1B1, STAB1, CCR2, TMEM176B), and immune responses (CD14, CD163) after administration of metformin for three months. We demonstrate for the first time a transcriptome-based molecular discrimination between metformin responders (delta HbA1c ≥ 1% or 12.6 mmol/mol) and non-responders (delta HbA1c < 1% or 12.6 mmol/mol), that is determined by expression levels of 56 genes, explaining 13.9% of the variance in the therapeutic efficacy of the drug. Moreover, we found a significant upregulation of IRS2 gene (log₂FC 0.89) in responders compared to non-responders before the use of metformin. Finally, we provide evidence for the mitochondrial respiratory complex I as one of the factors related to the high variability of the therapeutic response to metformin in patients with type 2 diabetes mellitus.

Importance of paraoxonase 1 (PON1) as an antioxidant and antiatherogenic enzyme in the cardiovascular complications of type 2 diabetes: Genotypic and phenotypic evaluation

Oxidant-antioxidant imbalance is involved in the etiology of different diseases, including cardiovascular diseases (CVDs), liver disorders, kidney diseases, cancers and diabetes mellitus. Antioxidant enzymes play a key role in striking an oxidant-antioxidant balance. Moreover, paraoxonase 1 (PON1) is an antioxidant enzyme that binds with high-density lipoprotein (HDL) in the circulation, and antioxidant and antiaterogenic properties of this lipoprotein are significantly associated with PON1. Research suggests PON1 contributes to the pathogenesis of certain human diseases such as type 2 diabetes (T2D). The association between PON1 and T2D appear to be reciprocal so that the disease significantly decreases PON1 levels and in turn, the genetics of PON1 may have a role the risk of susceptibility to T2D. Several factors that reduce the activity and concentration of PON1 in patients with T2D include increased glycation and loss-of-function polymorphisms. The genotypic and phenotypic evaluations of PON1 are therefore crucial for assessing the risk of cardiovascular complications in these patients, and strategies for increasing or restoring PON1 levels are useful for reducing or preventing their cardiovascular complications as their main cause of mortality. The present review aimed at discussing and emphasizing the key role of PON1 in T2D as a silent and dangerous disease.

Emerging Trends in Metformin Prescribing in the United States from 2000 to 2015

BACKGROUND

Metformin (MET) is used as first-line treatment for type 2 diabetes mellitus but has been shown to have pleiotropic effects that have expanded its use to various conditions. Limited current data exist regarding unconventional use within various patient populations.

OBJECTIVE

The aim of this study was to evaluate US FDA-approved and off-label MET utilization in the US from 2000 to 2015.

METHODS

We performed a retrospective analysis of outpatient MET prescribing in the US from 2000 to 2015. Data from the Medical Expenditure Panel Survey (MEPS) administered by the Agency of Healthcare Research and Quality were analyzed. Demographic characteristics, including age, sex, socioeconomic status, comorbidities, and region, were analyzed using the MEPS Household Component (HC). Prescription rates were defined as the annual number of MET prescriptions divided by the corresponding population estimate. Population denominators were derived using the MEPS HC. The MEPS estimates US populations based on sampled persons in the target population (civilian, non-institutionalized) for an entire year. MET prescribing is represented by population per 1000 persons. We determined if changes of MET prescribing were uniform across five age groups: < 18 years, 18-29 years, 30-49 years, 50-64 years, and 64 years and older.

RESULTS

An estimated 553,291,094 MET prescriptions were dispensed in the US from 2000 to 2015. Prescribing rates steadily increased from 2000 to 2015. FDA-approved MET prescription rates increased from 2.27 per 1000 persons in 2000 to 235 per 1000 persons in 2015, while off-label MET prescription rates increased from 0.74 per 1000 persons in 2000 to 20.3 per 1000 persons in 2015. The top indications for off-label MET use were endocrine disorders (45.8%), cardiovascular disorders (18.2%), female reproductive disorders (12.9%), and metabolic disorders (10.9%). MET prescribing rates for FDA-approved indications increased across all age groups in 2000 and 2015, with the most substantial increase seen in adults aged 50-64 years and > 65 years (1.7 per 1000 persons to 20.6 per 1000 persons, and 2.3 per 1000 persons to 18.7 per 1000 persons, respectively). While off-label MET increased across all age groups from 2000 to 2015, a tenfold increase (< 1.0 to 10.6) was seen in adults aged 30-49 years of age.

CONCLUSION

Overall, MET use has substantially increased within the past 15 years, which was mainly driven by older adults. Our study highlights the emerging prevalence of MET use in both FDA-approved and off-label indications.

Pathogenesis of Lipid Disorders in Insulin Resistance: a Brief Review

PURPOSE OF REVIEW

Insulin resistance (IR) is recognized to play an important role in the pathogenesis of dyslipidemia. This review summarizes the complex interplay between IR and dyslipidemia in people with and without diabetes.

RECENT FINDINGS

IR impacts the metabolism of triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein cholesterol (VLDL-C) by several mechanisms. Trials with insulin sensitizing therapies, including biguanides and thiazolidinediones, have provided inconsistent results on lipid lowering in people with and without diabetes. In this review, we focus on the pathophysiological interplay between IR and dyslipidemia and recapitulate lipid and lipoprotein data from insulin-sensitizing trials. Further research elucidating the reciprocal relationship between IR and dyslipidemia is needed to better target these important risk factors for cardiovascular disease.

Implication of critical pharmacokinetic gene variants on therapeutic response to metformin in Type 2 diabetes

Aim: Metformin, an oral hypoglycemic drug is the first line of treatment for Type 2 diabetes individuals. We studied the effect of critical gene single nucleotide polymorphisms  on the glucose lowering effect of metformin. Method: We performed a prospective study on 221 newly diagnosed, treatment-naive Type 2 diabetes subjects. Individuals were started with metformin monotherapy and followed up for 12 weeks. Results: Our association analysis revealed that SLC22A2 rs316019 and SLC47A2 rs12943590 were significantly associated with metformin drug response across co-dominant and dominant models, respectively. SLC22A2 rs316019 GG and SLC47A2 rs12943590 GA combined genotypes showed maximum average change in HbA1c level. Conclusion: The present study proposes a role of SLC22A2 rs316019 and SLC47A2 rs12943590 in the pharmacokinetic action of metformin.

Actions of metformin and statins on lipid and glucose metabolism and possible benefit of combination therapy

Patients with diabetes type 2 have an increased risk for cardiovascular disease and commonly use combination therapy consisting of the anti-diabetic drug metformin and a cholesterol-lowering statin. However, both drugs act on glucose and lipid metabolism which could lead to adverse effects when used in combination as compared to monotherapy. In this review, the proposed molecular mechanisms of action of statin and metformin therapy in patients with diabetes and dyslipidemia are critically assessed, and a hypothesis for mechanisms underlying interactions between these drugs in combination therapy is developed.

Effect of metformin monotherapy on serum lipid profile in statin-naïve individuals with newly diagnosed type 2 diabetes mellitus: a cohort study

Background

Cardiovascular disease is a major cause of mortality and morbidity in people with type 2 diabetes mellitus (T2DM). Studies have consistently identified dyslipidemia as an important risk factor for the development of macrovascular disease. The landmark United Kingdom Prospective Diabetes Study has shown that metformin therapy reduces cardiovascular events in overweight people with T2DM. This study investigates the effect of metformin monotherapy on serum lipid profile in statin-naïve individuals with newly diagnosed T2DM, and whether the effect, if any, is dosage-related.

Methods

This cohort study enrolled individuals exceeding 20 years of age, with recent onset T2DM, who received at least 12 months of metformin monotherapy and blood tests for serum lipid at 6-month intervals. Exclusion criteria involved people receiving any additional antidiabetic medication or lipid-lowering drug therapy. Lipid-modifying effect of metformin was recorded as levels of serum triglycerides (TG), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) measured at six month intervals.

Results

The study enrolled 155 participants with a mean age of 58.6 years and average glycosylated hemoglobin A_1c of 8%. After initiating metformin therapy, LDL-C was significantly reduced from 111 mg/dl to 102 mg/dL at 6 months (P < 0.001), TG was reduced from 132 mg/dl to 122 mg/dL at 12 months (P = 0.046), and HDL-C increased from 45.1 mg/dL to 46.9 mg/dL at 12 months (P = 0.02). However, increasing the dosage of metformin yielded no significant effect on its lipid-lowering efficacy.

Discussion

Metformin monotherapy appreciably improves dyslipidemia in statin-naive people with T2DM. Its lipid-modifying effect may be attributable to insulin sensitization, reduction of irreversibly glycated LDL-C, and weight loss. In practice, people with dyslipidemia who are ineligible for lipid-lowering agents may benefit from metformin therapy. Moreover, previous studies report a synergistic effect between metformin and statin, which may further reduce cardiovascular events in at-risk individuals. Overall, metformin is a safe and efficacious approach to alleviate dyslipidemia in people with newly diagnosed T2DM.

Liraglutide and Metformin alone or combined therapy for type 2 diabetes patients complicated with coronary artery disease

BACKGROUND

This study is to compare the effects of Liraglutide and Metformin alone or combined treatment on the cardiac function in T2DM patients complicated with CAD.

METHODS

120 T2DM patients were included at Endocrinology Department of Tianjin First Center Hospital (Tianjin, China) from April 2012 to September 2013. The study contained two sections. Section 1: 30 patients in group 1 was treated with Liraglutide (Novo Nordisk) (1.2 mg/d), and 30 patients in group 2 with Metformin (Shiguibao) (1500 mg/d) for 24 weeks. Section 2: 30 patients in group1 was treated with Liraglutide (1.8 mg/d) and 30 in group 2 with Liraglutide (1.2 mg/d) plus Metformin (1500 mg/d) for 24 weeks. Fasting blood glucose (FBG), postprandial glucose (PPG), glycated hemoglobin (HbA1c), body mass index (BMI), blood pressure (BP), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), C reactive protein (CRP), left ventricular end-diastolic diameter (LVEDD), ejection fraction (EF) and the ratio of early (E) to late (A) ventricular filling velocities (E/A ratio) were measured before and after the 24-week treatment.

RESULTS

After 24-week treatment, when blood glucose level was controlled in 4 groups, Liraglutide alone treatment showed better improvements than on all measuring except TG in Section 1, however, combined treatment of Liraglutide and Metformin showed better improvements on all measuring except BMI, TG and BP in Section 2.

CONCLUSIONS

With similar glycemic control, the Liraglutide (1.2 mg/d) monotherapy showed the better effects than either Metformin alone, or combination of Liraglutide and Metformin on lipid metabolism and cardiovascular function.

TRIAL REGISTRATION

This trial was registered at Chinese Clinical Trial Registry ( chictr.org.cn ) # ChiCTR-IPR-16008578 .

Metformin-like antidiabetic, cardio-protective and non-glycemic effects of naringenin: Molecular and pharmacological insights

Metformin is a widely used drug for the treatment of type 2 diabetes (T2D). Its blood glucose-lowering effects are initially due to inhibition of hepatic glucose production and increased peripheral glucose utilization. Metformin has also been shown to have several beneficial effects on cardiovascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular complications in patients with diabetes. Adenosine Monophosphate Activated-Protein Kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Recent evidence shows that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profiles, blood pressure and insulin-resistance making it a novel therapeutic target in the treatment of T2D. Naringenin a flavonoid found in high concentrations as its glycone naringin in citrus fruits, has been reported to have antioxidant, antiatherogenic, anti- dyslipidemic and anti-diabetic effects. It has been shown that naringenin exerts its anti-diabetic effects by inhibition of gluconeogenesis through upregulations of AMPK hence metformin-like effects. Naringin has further been shown to have non-glycemic affects like metformin that mitigate inflammation and cell proliferation. This review evaluates the potential of naringenin as anti-diabetic, anti-dyslipidemic anti-inflammatory and antineoplastic agent similar to metformin and proposes its further development for therapeutic use in clinical practice.

Association between the synonymous variant organic cation transporter 3 (OCT3)-1233G>A and the glycemic response following metformin therapy in patients with type 2 diabetes

OBJECTIVES

Organic cation transporter 3 (OCT3) as a high-capacity transporter contribute to the metabolism of metformin. The present study was conducted to determine the genotype frequencies of the variant OCT3-1233G>A (rs2292334) in patients with newly diagnosed type 2 diabetes (T2D) and its relationship with response to metformin.

MATERIALS AND METHODS

This study included 150 patients with T2D who were classified into two groups following three months of metformin therapy: responders (by more than 1% reduction in HbA1c from baseline) and nonresponders (less than 1% reduction in HbA1c from baseline). PCR-based restriction fragment length polymorphism (RFLP) served to genotype OCT3-564G>A variant.

RESULTS

The parameters such as HbA1c (P<0.001) and BMI (P<0.001) in both patients with GA + AA genotype and GG genotype decreased significantly following 3 months of metformin therapy compared with baseline. The mean reduction in HbA1c levels following 3 months was higher in patients with the A allele (0.77% reduction from baseline) than in those with the homozygous G allele (0.54% reduction from baseline). Also, in GA + AA genotypes compared with GG genotypes, the mean reduction in HbA1c values from baseline was 0.34% for responders and 0.14% for non-responders.

CONCLUSION

Considering the roles of genetic variations in the function of metformin transporters, the effect of variations such as 1233G>A in the OCT3, which is a high-capacity transporter widely expressed in various tissues cannot be ignored. Comparing the allele frequencies of OCT3-1233G>A variant in our study and different ethnic populations confirm that the variant is a highly polymorphic variant.

Allele frequency and genotype distribution of a common variant in the 3´-untranslated region of the SLC22A3 gene in patients with type 2 diabetes: Association with response to metformin

Background:

Organic cation transporter 3 (OCT3) is an excellent transporter for metformin, which is used as first-line therapy for type 2 diabetes (T2D). OCT3 genetic variants may influence the clinical response to metformin. This study aimed to determine the genotype and allele frequency of OCT3-564G>A (rs3088442) variant and its role in the glycemic response to metformin in patients with newly diagnosed T2D.

Materials and Methods:

Based on the response to metformin, 150 patients were classified into two groups: Sixty-nine responders (decrease in glycated hemoglobin [HbA1c] values by more than 1% from the baseline) and 81 nonresponders (decrease in HbA1c values <1% from the baseline). HbA1c levels were determined by chromatography. The variant OCT3-564G>A was genotyped using polymerase chain reaction - based restriction fragment length polymorphism.

Results:

The genotypes frequencies were 51.3% GG, 36% AG, and 12.7% AA. Allele frequency of major allele (G) and minor allele (A) in OCT3-564G>A variant was found to be 0.69 and 0.31, respectively. Fasting glucose, HbA1c, body mass index, and lipid profile in both GG genotypes and GA + AA group decreased significantly after 3 months of metformin therapy compared with baseline (P < 0.05). In both responders and nonresponders, HbA1c and fasting glucose levels were lower in patients with the GA + AA genotype than in those with the GG genotype; however, the differences were not statistically significant (P > 0.05).

Conclusion:

The A allele frequency (which may be a protective allele against coronary heart disease) in the Iranian diabetic patients was lower than Iranian, Caucasian and Japanese healthy populations. Metformin is useful in improving the lipid profile, in addition to its impacts in glycemic control, and these effects are regardless of OCT3-564G>A variant.