Metformin therapy and kidney disease: a review of guidelines and proposals for metformin withdrawal around the world

Untargeted plasma 1H NMR-based metabolomic profiling in different stages of chronic kidney disease

Chronic kidney disease (CKD) is a serious public health issue affecting thousands of people worldwide. CKD diagnosis is usually made by Estimated Glomerular Filtration Rate (eGFR) and albuminuria, which limit the knowledge of the mechanisms behind CKD progression. The aim of the present study was to identify changes in the metabolomic profile that occur as CKD advances. In this sense, 77 plasma samples from patients with CDK were evaluated by 1D and 2D Nuclear Magnetic Resonance Spectroscopy (NMR). The NMR data showed significant changes in the metabolomic profile of CKD patients and the control group. Principal component analysis (PCA) clustered CKD and control patients into three distinct groups, control, stage 1 (G1)-stage 4 (G4) and stage 5 (G5). Lactate, glucose, acetate and creatinine were responsible for discriminating the control group from all the others CKD stages. Valine, alanine, glucose, creatinine, glutamate and lactate were responsible for the clustering of G1-G4 stages. G5 was discriminated by calcium ethylenediamine tetraacetic acid, magnesium ethylenediamine tetraacetic acid, creatinine, betaine/choline/trimethylamine N-oxide (TMAO), lactate and acetate. CKD G5 plasma pool which was submitted in MetaboAnalyst 4.0 platform (MetPA) analysis and showed 13 metabolic pathways involved in CKD physiopathology. Metabolic changes associated with glycolysis and gluconeogenesis allowed discriminating between CKD and control patients. The determination of involved molecules in TMAO generation in G5 suggests an important role in this uremic toxin linked to CKD and cardiovascular diseases. The aforementioned results propose the feasibility of metabolic assessment of CKD by NMR during treatment and disease progression.

Cardiac Dysfunction Due to Thiamine Deficiency after Hemodialysis for Biguanide-related Lactic Acidosis

Biguanide is an ideal drug for the treatment of type 2 diabetes mellitus. When used appropriately, the incidence of lactic acidosis is reported to be very low. Risk factors associated with biguanide-related lactic acidosis include chronic kidney disease, congestive heart failure, alcohol use, severe dehydration, shock, hypoxic states, sepsis, and advanced age. We herein report a case of cardiac dysfunction due to thiamine deficiency after hemodialysis in a patient with suspected biguanide-related lactic acidosis. Patients who develop severe lactic acidosis while taking biguanides should be given a large dose of thiamine without delay, given the possibility of thiamine deficiency as a complication.

Compliance with Prescription Guidelines for Glucose-Lowering Therapies According to Renal Function: Real-Life Study in Inpatients of Internal Medicine, Endocrinology and Cardiology Units

Background and objectives: Renal failure is a contraindication for some glucose-lowering drugs and requires dosage adjustment for others, particularly biguanides, sulfonylureas, and inhibitors of dipeptidyl peptidase 4. In this study, we assessed adherence to prescription recommendations for glucose-lowering drugs according to renal function in hospitalized diabetic subjects. Materials and Methods: This prospective cohort study was carried out over a 2-year period in a university hospital. Glomerular filtration rate (GFR) was determined by averaging all measurements performed during hospitalization. Glucose-lowering drug dosages were analyzed according to the recommendations of the relevant medical societies. Results: In total, 2071 diabetic patients (53% hospitalized in cardiology units) were examined. GFR was <30 mL/min/1.73 m² in 13.4% of these patients, 30–44 in 15.1%, 45–60 in 18.3%, and >60 in 53.3%. Inappropriate oral glucose-lowering treatments were administered to 273 (13.2%) patients, including 53 (2.6%) with a contraindication. In cardiology units, 53.1% and 14.3% of patients had GFRs of <60 and <30 mL/min/1.73 m², respectively, and 179 (15.4%) patients had a contraindication or were prescribed an excessive dose of glucose-lowering drugs. Conclusions: We showed that the burden of inappropriate prescriptions is high in diabetic patients. Given the high number of patients receiving these medications, particularly in cardiology units, a search for potential adverse effects related to these drugs should be performed.

A Comprehensive Whole-Body Physiologically Based Pharmacokinetic Drug-Drug-Gene Interaction Model of Metformin and Cimetidine in Healthy Adults and Renally Impaired Individuals

Background

Metformin is a widely prescribed antidiabetic BCS Class III drug (low permeability) that depends on active transport for its absorption and disposition. It is recommended by the US Food and Drug Administration as a clinical substrate of organic cation transporter 2/multidrug and toxin extrusion protein for drug–drug interaction studies. Cimetidine is a potent organic cation transporter 2/multidrug and toxin extrusion protein inhibitor.

Objective

The objective of this study was to provide mechanistic whole-body physiologically based pharmacokinetic models of metformin and cimetidine, built and evaluated to describe the metformin-SLC22A2 808G>T drug–gene interaction, the cimetidine-metformin drug–drug interaction, and the impact of renal impairment on metformin exposure.

Methods

Physiologically based pharmacokinetic models were developed in PK-Sim^® (version 8.0). Thirty-nine clinical studies (dosing range 0.001–2550 mg), providing metformin plasma and urine data, positron emission tomography measurements of tissue concentrations, studies in organic cation transporter 2 polymorphic volunteers, drug–drug interaction studies with cimetidine, and data from patients in different stages of chronic kidney disease, were used to develop the metformin model. Twenty-seven clinical studies (dosing range 100–800 mg), reporting cimetidine plasma and urine concentrations, were used for the cimetidine model development.

Results

The established physiologically based pharmacokinetic models adequately describe the available clinical data, including the investigated drug–gene interaction, drug–drug interaction, and drug–drug–gene interaction studies, as well as the metformin exposure during renal impairment. All modeled drug–drug interaction area under the curve and maximum concentration ratios are within 1.5-fold of the observed ratios. The clinical data of renally impaired patients shows the expected increase in metformin exposure with declining kidney function, but also indicates counter-regulatory mechanisms in severe renal disease; these mechanisms were implemented into the model based on findings in preclinical species.

Conclusions

Whole-body physiologically based pharmacokinetic models of metformin and cimetidine were built and qualified for the prediction of metformin pharmacokinetics during drug–gene interaction, drug–drug interaction, and different stages of renal disease. The model files will be freely available in the Open Systems Pharmacology model repository. Current guidelines for metformin treatment of renally impaired patients should be reviewed to avoid overdosing in CKD3 and to allow metformin therapy of CKD4 patients.

Electronic supplementary material

The online version of this article (10.1007/s40262-020-00896-w) contains supplementary material, which is available to authorized users.

Metformin prevents stroke damage in non-diabetic female mice with chronic kidney disease

Chronic kidney disease (CKD) worsens ischemic stroke severity in both patients and animals. In mice, these poorer functional outcomes are associated with decreased brain activity of AMP-activated protein kinase (AMPK), a molecule that recently emerged as a potential therapeutic target for ischemic stroke. The antidiabetic drug metformin, a well-known activator of AMPK, has improved stroke outcomes in diabetic patients with normal renal function. We investigated whether chronic metformin pre-conditioning can rescue AMPK activity and prevent stroke damage in non-diabetic mice with CKD. Eight-week-old female C57BL/6J mice were assigned to CKD or SHAM groups. CKD was induced through right kidney cortical electrocautery, followed by left total nephrectomy. Mice were then allocated to receive metformin (200 mg/kg/day) or vehicle for 5 weeks until stroke induction by transient middle cerebral artery occlusion (tMCAO). The infarct volumes were lower in CKD mice exposed to metformin than in vehicle-treated CKD mice 24 h after tMCAO. Metformin pre-conditioning of CKD mice improved their neurological score, grip strength, and prehensile abilities. It also enhanced AMPK activation, reduced apoptosis, increased neuron survival and decreased microglia/macrophage M1 signature gene expression as well as CKD-induced activation of the canonical NF-κB pathway in the ischemic lesions of CKD mice.

Evidence-based treatment of hyperglycaemia with incretin therapies in patients with type 2 diabetes and advanced chronic kidney disease

Type 2 diabetes is the leading cause of chronic kidney disease (CKD). The prevalence of CKD is growing in parallel with the rising number of patients with type 2 diabetes globally. At present, the optimal approach to glycaemic control in patients with type 2 diabetes and advanced CKD (categories 4 and 5) remains uncertain, as these patients were largely excluded from clinical trials of glucose-lowering therapies. Nonetheless, clinical trial data are available for the use of incretin therapies, dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists, for patients with type 2 diabetes and advanced CKD. This review discusses the role of incretin therapies in the management of these patients. Because the presence of advanced CKD in patients with type 2 diabetes is associated with a markedly elevated risk of cardiovascular disease (CVD), treatment strategies must include the reduction of both CKD and CVD risks because death, particularly from cardiovascular causes, is more probable than progression to end-stage kidney disease. The management of hyperglycaemia is essential for good diabetes care even in advanced CKD. Current evidence supports an individualized approach to glycaemic management in patients with type 2 diabetes and advanced CKD, taking account of the needs of each patient, including the presence of co-morbidities and concomitant therapies. Although additional studies are needed to establish optimal strategies for glycaemic control in patients with type 2 diabetes and advanced CKD, treatment regimens with currently available pharmacotherapy can be individually tailored to meet the needs of this growing patient population.

Clinical Characteristics and Prevalence of Comorbidities according to Metformin Use in Korean Patients with Type 2 Diabetes

METHODS

This cross-sectional study based on the Korean National Diabetes Program 2 registry used its baseline clinical data collected from seven participating university hospitals in Korea. Patients with no significant changes in their oral hypoglycemic agents and no diabetes-related complications within the year prior to participation were enrolled. Patients' clinical characteristics according to metformin use were analyzed.

RESULTS

Among 858 subjects included in the analyses, 706 were metformin users and 152 were nonmetformin users. Metformin users were significantly younger and had higher and glycated hemoglobin with significantly lower rates of accompanying microvascular complications such as retinopathy, cataracts, overt proteinuria, renal insufficiency, and peripheral neuropathy than nonusers. Meanwhile, there was a significantly lower prevalence of malignancy and depression among metformin users. These associations remained significant in multivariate analyses. The prevalence rate of macrovascular complications was not significantly different between the two groups.

CONCLUSIONS

There were significant differences with respect to clinical characteristics and comorbidity prevalence according to metformin use among Korean type 2 diabetes patients. Long-term follow-up of these patients is necessary to observe how this difference will affect clinical outcomes for these patients.

Type 2 diabetes treatment and progression of chronic kidney disease in Italian family practice

AIMS

Progressive chronic kidney disease represents a dreadful complication of type 2 diabetes mellitus (T2DM). We tested the pattern of use and the renal effects of old glucose-lowering drugs in T2DM patients cared for by Italian general practitioners (GPs).

METHODS

Data of 2606 T2DM patients were extracted from the databases of GPs, who do not have access to the most recent glucose-lowering drugs in Italy. The rate of kidney function decline was calculated by CKD-EPI_cr, based on two consecutive creatinine values.

RESULTS

Metformin was used in 55% of cases, either alone or with sulfonylureas/repaglinide, across the whole spectrum of CKD (from 66% in stage G1 to only 8% in G4). Sulfonylurea use peaked at 21-22% in stage G2-G3a, whereas repaglinide use significantly increased from 8% in G1 to 22% in G4. The median rate of CKD decline was - 1.64 mL/min/1.73 m² per year; it was higher in G1 (- 3.22 per year) and progressively lower with CKD severity. 826 cases (31.7%) were classified as fast progressors (eGFR decline more negative than - 5 mL/min/1.73 m² per year). The risk of fast progressing CKD was associated with increasing BMI, albuminuria, and sulfonylurea use, alone (OR, 1.47; 95% confidence interval, 1.16-1.85), or in association with metformin (OR, 1.40; 95% CI 1.04-1.88). No associations were demonstrated for metformin, cardiovascular and lipid lowering drug use.

CONCLUSION

In the setting of Italian family practice, sulfonylurea use is associated with progressive CKD in patients with T2DM. Metformin, at doses progressively reduced according to CKD stages, as recommended by guidelines, is not associated with fast progression.

Pharmacotherapy of type 2 diabetes in patients with chronic liver disease: focus on nonalcoholic fatty liver disease

INTRODUCTION

Pharmacotherapy used to treat type 2 diabetes mellitus (T2DM) is facing a paradigm shift in clinical practice with recent cardiovascular (CV) outcome trials having a substantial impact on drug prescription with treatment having a more tailored approach. In patients with T2DM, the issue of chronic liver disease is multifaceted. However, a clinical evidence is emerging on the beneficial effect of antidiabetic medications on nonalcoholic fatty liver disease (NAFLD).

AREAS COVERED

The authors provide a synopsis on the current and upcoming pharmacotherapy for NAFLD, including the challenges with their development, focusing on drugs for T2DM. Clinical data on the potential benefits and safety issues are assessed with the aim of proposing an individualized algorithm for patient management. Both MEDLINE and ClinicalTrials.Gov are used to derive the relevant information.

EXPERT OPINION

Considering the pivotal role of insulin resistance in NAFLD, insulin sensitizers should be the treatment of choice. Accordingly, pioglitazone is the only drug with a significant effect on liver fibrosis, the driver of disease progression and long-term outcome. Among new glucose-lowering drugs, glucagon-like-peptide 1 receptor agonists or sodium-glucose cotransporter type 2 inhibitors have shown positive effects in phase II studies and are qualifying as potential candidates for NAFLD treatment in diabetes.

Metformin Treatment in Patients With Type 2 Diabetes and Chronic Kidney Disease Stages 3A, 3B, or 4

OBJECTIVE

This study was conducted to define a safe, effective dose regimen for metformin in moderate and severe chronic kidney disease (CKD; stages 3A/3B and 4, respectively), after the lifting of restrictions on metformin use in patients with diabetes with moderate-to-severe CKD in the absence of prospective safety and efficacy studies.

RESEARCH DESIGN AND METHODS

Three complementary studies were performed: 1) a dose-finding study in CKD stages 1-5, in which blood metformin concentrations were evaluated during a 1-week period after each dose increase; 2) a 4-month metformin treatment study for validating the optimal metformin dose as a function of the CKD stage (3A, 3B, and 4), with blood metformin, lactate, and HbA_1c concentrations monitored monthly; and 3) an assessment of pharmacokinetic parameters after the administration of a single dose of metformin in steady-state CKD stages 3A, 3B, and 4.

RESULTS

First, in the dose-finding study, the appropriate daily dosing schedules were 1,500 mg (0.5 g in the morning [qam] +1 g in the evening [qpm]) in CKD stage 3A, 1,000 mg (0.5 g qam + 0.5 g qpm) in CKD stage 3B, and 500 mg (qam) in CKD stage 4. Second, after 4 months on these regimens, patients displayed stable metformin concentrations that never exceeded the generally accepted safe upper limit of 5.0 mg/L. Hyperlactatemia (>5 mmol/L) was absent (except in a patient with myocardial infarction), and HbA_1c levels did not change. Third, there were no significant differences in pharmacokinetic parameters among the CKD stage groups.

CONCLUSIONS

Provided that the dose is adjusted for renal function, metformin treatment appears to be safe and still pharmacologically efficacious in moderate-to-severe CKD.

Risk of acute kidney injury and survival in patients treated with Metformin: an observational cohort study

BACKGROUND

Whether metformin precipitates lactic acidosis in patients with chronic kidney disease (CKD) remains under debate. We examined whether metformin use was associated with an increased risk of acute kidney injury (AKI) as a proxy for lactic acidosis and whether survival among those with AKI varied by metformin exposure.

METHODS

All individuals with type 2 diabetes and available prescribing data between 2004 and 2013 in Tayside, Scotland were included. The electronic health record for diabetes which includes issued prescriptions was linked to laboratory biochemistry, hospital admission, death register and Scottish Renal Registry data. AKI events were defined using the Kidney Disease Improving Global Outcomes criteria with a rise in serum creatinine of at least  26.5 μmol/l or a rise of greater than 150% from baseline for all hospital admissions. Cox Regression Analyses were used to examine whether person-time periods in which current metformin exposure occurred were associated with an increased rate of first AKI compared to unexposed periods. Cox regression was also used to compare 28 day survival rates following first AKI events in those exposed to metformin versus those not exposed.

RESULTS

Twenty-five thousand one-hundred fourty-eight patients were included with a total person-time of 126,904 person years. 4944 (19.7%) people had at least one episode of AKI during the study period. There were 32.4 cases of first AKI/1000pyrs in current metformin exposed person-time periods compared to 44.9 cases/1000pyrs in unexposed periods. After adjustment for age, sex, diabetes duration, calendar time, number of diabetes drugs and baseline renal function, current metformin use was not associated with AKI incidence, HR 0.94 (95% CI 0.87, 1.02, p = 0.15). Among those with incident AKI, being on metformin at admission was associated with a higher rate of survival at 28 days (HR 0.81, 95% CI 0.69, 0.94, p = 0.006) even after adjustment for age, sex, pre-admission eGFR, HbA1c and diabetes duration.

CONCLUSIONS

Contrary to common perceptions, we found no evidence that metformin increases incidence of AKI and was associated with higher 28 day survival following incident AKI.

Lactic acidosis: relationship between metformin levels, lactate concentration and mortality

AIM

The role of metformin in lactic acidosis is regularly questioned. Arguments against a causal role for metformin in lactic acidosis occurrence are the lack of correlation between plasma metformin and lactate levels, as well as between metformin plasma levels and mortality. We aim to analyse these correlations in a large series of lactic acidosis cases recorded in the French nationwide pharmacovigilance database.

METHODS

All cases of lactic acidosis spontaneously reported between 1985 and October 2013 associated with metformin exposure were extracted from the pharmacovigilance database. We assessed the statistical correlations between prescribed daily doses of metformin, plasma concentrations of metformin and lactate, pH and plasma creatinine, as well as the relationship between mortality and these variables.

RESULTS

Seven hundred and twenty-seven cases of lactic acidosis were reported during the period. Metformin plasma concentration was documented for 260 patients, lactate plasma concentration for 556 patients, pH for 502 patients, creatinine for 397 patients and the vital outcome for 713 patients. Metformin plasma concentration, lactate concentration, pH and plasma creatinine were all correlated (P < 0.001). There were significant differences between surviving and deceased patients in terms of metformin plasma levels (25.2 vs. 37.4 mg/l, P = 0.002) and lactate concentrations (10.8 vs. 16.3 mmol/l, P < 0.001). Thirty per cent of patients died when metformin concentration was > 5 mg/l compared with 11% for patients with concentration < 5 mg/l (P = 0.003).

CONCLUSIONS

Our data suggest that metformin accumulation contributes to the pathogenesis and prognosis of lactic acidosis.

Epidemiology of lactic acidosis in type 2 diabetes patients with metformin in Japan

PURPOSE

To estimate the incidence of lactic acidosis (LA) and role of metformin in Japanese patients with type 2 diabetes mellitus (T2DM) treated with anti-diabetes drugs.

METHODS

This retrospective propensity score matched cohort study was conducted using the Japanese Medical Data Vision claims database. T2DM patients aged 18 or above who received diabetes drugs during January 2010 through August 2014 were identified. Cases of LA were identified based on reimbursement codes and confirmed by lactic acid test and subsequent treatment by hemodialysis or intravenous sodium bicarbonate. Poisson regression and Cox proportional hazard models were used to estimate the incidence and assess if metformin use was associated with increased risk of LA.

RESULTS

Thirty cases of LA were identified among 283 491 treated T2DM patients with 504 169 patient-years of follow-up. Crude incidence of LA was 5.95 per 100 000 patient-years. T2DM patients with chronic kidney disease (CKD) were seven-fold more likely to develop LA than those without CKD (adjusted hazard ratio (aHR), 7.33, 95%CI, 3.17-16.96). Use of metformin was not associated with risk of LA in the study population (aHR, 0.92, 95%CI, 0.33-2.55), and in the propensity score matched cohort (aHR, 0.90, 95%CI, 0.26-3.11). Similar findings were observed among diabetes patients with chronic liver disease (CLD) and CKD. The age-sex adjusted incidence rates in metformin users and non-users were 5.80 and 5.78 per 100 000 person-years, respectively (Incidence rate ratio, 1.00, p = 0.99).

CONCLUSIONS

This study found that use of metformin was not associated with increased risk of LA in diabetic patients including those with CKD or CLD. © 2016 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.

Oral antidiabetics use among diabetic type 2 patients with chronic kidney disease. Do nephrologists take account of recommendations?

BACKGROUND

There is an increasing prevalence of diabetes type 2 and chronic kidney disease, challenging appropriate prescribing of oral anti-diabetic drugs (OADs).

METHODS

We have described the practice patterns of 13 nephrologists in 4 centers, in a cohort of 301 consecutive adult type 2 diabetic patients. Among oral anti-diabetic prescriptions, we have detailed drugs dosage for each subject, with 3 different formulae for estimating glomerular filtration rate (GFR) and its adequation according to the latest ERBP recommendations (2015). As individuals were mostly obese in this work, we also compare adequacy rates using both standard indexed CKD-EPI formula and CKD-EPI formula de-indexed from body surface area.

RESULTS

Using the CKD-EPI formula as the reference method for estimating GFR, 53.5% of patients were outside the recommendations, mostly for metformin (30% of the whole cohort) and for sitagliptin (17.9% of the whole cohort). With Cockcroft and Gault formula, 38.2% of persons were outside recommendations and 45.9% (p<0.001) with CKD-EPI de-indexed. Among individuals consulting a nephrologist for the first time (n=90), 61.1% were outside recommendations (p=0.1). Among those persons under diabetologist supervision (n=103), 63.1% were outside recommendations (p=0.09), and were taking significantly more often metformin and insulin.

CONCLUSION

We have found a substantial number of inadequate OAD prescriptions in type 2 diabetic patients with chronic kidney disease. The proportion of individuals outside guidelines was strongly affected by the method used for estimating GFR and by the type of practice, i.e., specialists versus general practitioners.

Retrospective analysis of lactic acidosis-related parameters upon and after metformin discontinuation in patients with diabetes and chronic kidney disease

PURPOSE

To investigate association between renal functions, lactic acid levels and acid-base balance in type 2 diabetes patients with chronic kidney disease under metformin treatment and after metformin discontinuation in a real-life setting.

METHODS

A total of 65 patients with diabetes (mean age 68.5 ± 8.9 years, 56.9 % females) in whom metformin treatment was discontinued due to reduced glomerular filtration rate (GFR) were included in this retrospective study. Data on patient demographics, metformin treatment and laboratory findings on the last day of metformin treatment and 2-3 weeks after metformin discontinuation including blood lactate and creatinine, estimated glomerular filtration rate (eGFR) and acid-base balance measurements in blood [pH, bicarbonate, base excess] were collected from medical records. The correlation of lactate levels with eGFR, blood pH and creatinine levels and changes in laboratory findings after metformin discontinuation were evaluated.

RESULTS

Before metformin discontinuation, hyperlactatemia was observed in 78.5 % of patients and metabolic acidosis in 36.9 % of patients, but none had lactic acidosis. Patients with normolactatemia and hyperlactatemia were similar in terms of metformin dosage and laboratory parameters. Lactate levels were not significantly correlated with serum creatinine (r = -0.14; p = 0.263) and eGFR (r = 0.11, p = 0.374). After metformin discontinuation, a significant decrease was observed in median lactate levels (from 2.20 to 1.85 mmol/L; p = 0.002).

CONCLUSION

In conclusion, our findings support the low risk of MALA among patients with mild-to-moderate renal impairment and the likelihood of metformin to be an innocent bystander without a pathogenic role in the lactic acidosis in most cases.

Metformin associated lactic acidosis (MALA): clinical profiling and management

Metformin (MF) accumulation during acute kidney injury is associated with high anion gap lactic acidosis type B (MF-associated lactic acidosis, MALA), a serious medical condition leading to high mortality. Despite dose adjustment for renal failure, diabetic patients with chronic kidney disease (CKD) stage III-IV are at risk for rapid decline in renal function by whatever reason, so that MF toxicity might arise if the drug is not timely withdrawn. Sixteen consecutive patients were admitted to our Hospital's Emergency Department with clinical findings consistent with MALA. Fifteen had prior history of CKD, 60 % of them with GFR between 30 and 60 ml/min. Of these, 5 required mechanical ventilation and cardiovascular support; 3 promptly recovered renal function after rehydration, whereas 10 (62 %) required continuous veno-venous renal replacement treatment. SOFA and SAPS II scores were significantly related to the degree of lactic acidosis. In addition, lactate levels were relevant to therapeutic choices, since they were higher in dialyzed patients than in those on conservative treatment (11.92 mmol/l vs 5.7 mmol/l, p = 0.03). The overall death rate has been 31 %, with poorer prognosis for worse acidemia, as serum pH was significantly lower in non-survivors (pH 6.96 vs 7.16, p > 0.04). Our own data and a review of the literature suggest that aged, hemodynamically frail patients, with several comorbidities and CKD, are at greater risk of MALA, despite MF dosage adjustment. Moreover, renal replacement therapy rather than simple acidosis correction by administration of alkali seems the treatment of choice, based on eventual renal recovery and overall outcome.

Management of diabetes mellitus in individuals with chronic kidney disease: therapeutic perspectives and glycemic control

The purpose of this study was to evaluate the therapeutic options for diabetes treatment and their potential side effects, in addition to analyzing the risks and benefits of tight glycemic control in patients with diabetic kidney disease. For this review, a search was performed using several pre-defined keyword combinations and their equivalents: "diabetes kidney disease" and "renal failure" in combination with "diabetes treatment" and "oral antidiabetic drugs" or "oral hypoglycemic agents." The search was performed in PubMed, Endocrine Abstracts and the Cochrane Library from January 1980 up to January 2015. Diabetes treatment in patients with diabetic kidney disease is challenging, in part because of progression of renal failure-related changes in insulin signaling, glucose transport and metabolism, favoring both hyperglycemic peaks and hypoglycemia. Additionally, the decline in renal function impairs the clearance and metabolism of antidiabetic agents and insulin, frequently requiring reassessment of prescriptions. The management of hyperglycemia in patients with diabetic kidney disease is even more difficult, requiring adjustment of antidiabetic agents and insulin doses. The health team responsible for the follow-up of these patients should be vigilant and prepared to make such changes; however, unfortunately, there are few guidelines addressing the nuances of the management of this specific population.

Lactic Acidosis in a Patient with Type 2 Diabetes Mellitus

Lactic acidosis occurs when lactate production exceeds its metabolism. There are many possible causes of lactic acidosis, and in any given patient, several causes may coexist. This Attending Rounds presents a case in point. Metformin's role in the pathogenesis of lactic acidosis in patients with diabetes mellitus is complex, as the present case illustrates. The treatment of lactic acidosis is controversial, except for the imperative to remedy its underlying cause. The use of sodium bicarbonate to treat the often alarming metabolic derangements may be quite efficacious in that regard but is of questionable benefit to patients. Renal replacement therapies (RRTs) have particular appeal in this setting for a variety of reasons, but their effect on clinical outcomes is untested.

Comparison of treatment with sitagliptin or sulfonylurea in patients with type 2 diabetes mellitus and mild renal impairment: a post hoc analysis of clinical trials

INTRODUCTION

Impaired renal function is a major complication of type 2 diabetes mellitus (T2DM). Mild renal impairment is present in 38% of patients with T2DM and may impact choice of antihyperglycemic agent. Sulfonylureas and dipeptidyl peptidase-4 (DPP-4) inhibitors are commonly used to treat hyperglycemia in patients with T2DM and renal impairment. Although in general sulfonylurea use is associated with an increased risk of hypoglycemia and weight gain, while DPP-4 inhibitor use is associated with a low risk of hypoglycemia, and is weight neutral, the relative efficacy and tolerability of these agents in patients with mild renal impairment has not been evaluated.

METHODS

In a post hoc analysis, data from 1,211 subjects with T2DM and mild renal impairment (estimated glomerular filtration rates of 60 to <90 mL/min/1.73 m(2)), who completed 25 or 30 weeks of one of three double-blind clinical trials comparing the DPP-4 inhibitor sitagliptin 100 mg/day with sulfonylureas in titrated doses, were pooled. The analysis compared change from baseline in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), body weight, incidence of symptomatic hypoglycemia and the percentages of subjects meeting a composite endpoint of HbA1c decrease >0.5% without symptomatic hypoglycemia or body weight gain between sitagliptin and sulfonylurea treatment groups.

RESULTS

HbA1c and FPG decreased similarly with sitagliptin or sulfonylurea. A lower incidence of hypoglycemia was observed with sitagliptin. Body weight decreased with sitagliptin but increased with sulfonylurea. A greater percentage of subjects treated with sitagliptin (41.1%) than treated with sulfonylurea (16.9%) achieved the composite endpoint of >0.5% HbA1c reduction with no symptomatic hypoglycemia or body weight gain.

CONCLUSION

In this analysis of subjects with T2DM and mild renal impairment, treatment with sitagliptin provided glycemic efficacy similar to sulfonylurea, with less hypoglycemia and with body weight loss compared to body weight gain seen with sulfonylurea.

TRIAL REGISTRATIONS

ClinicalTrials.gov #NCT00482079, #NCT00094770, #NCT00701090.

Metformin use in kidney transplant recipients in the United States: an observational study

BACKGROUND/AIMS

Although metformin is contraindicated in patients with increased serum creatinine levels (≥1.5 mg/dl in men, ≥1.4 mg/dl in women) in the United States, its use has not been systematically examined in kidney transplant recipients. We aimed to determine the frequency of metformin use and its associations among kidney transplant recipients, and to assess allograft and patient survival associated with metformin use.

METHODS

In this retrospective cohort study, we linked Scientific Registry of Transplant Recipients data for all incident kidney transplants 2001-2012 and national pharmacy claims (n = 46,914). We compared recipients having one or more pharmacy claims for a metformin-containing product (n = 4,609) and recipients having one or more claims for a non-metformin glucose-lowering agent (n = 42,305).

RESULTS

On average, metformin claims were filled later after transplant and were associated with higher estimated glomerular filtration rates before the first claim. Median serum creatinine (mg/dl) levels before the first claim were lower in recipients with metformin claims than in those with non-metformin claims (1.3 [interquartile range 1.0-1.7] vs. 1.6 [1.2-2.5], respectively; p < 0.0001). Metformin was associated with lower adjusted hazards for living donor (0.55, 95% confidence interval 0.38-0.80; p = 0.002) and deceased donor (0.55, 0.44-0.70; p < 0.0001) allograft survival at 3 years posttransplant, and with lower mortality.

CONCLUSIONS

Despite metformin being contraindicated in renal dysfunction, many kidney transplant recipients receive it, and it is not associated with worse patient or allograft survival.

Is metformin ready for prime time in pregnancy? Probably not yet

Metformin is one of the most commonly used drugs to treat type 2 diabetes and is safe and effective. Its main mechanism of action is thought to be the activation of AMP-activated protein kinase (AMPK) via inhibition of mitochondrial ATP generation. Recent use of metformin as an 'insulin sensitizer' in women with polycystic ovarian syndrome to increase fertility has been successful and resulted in the chance observation that continued use during pregnancy appeared to be safe. There are few studies of metformin in animal models of diabetic pregnancy. However, some data have implicated fetal AMPK activation in neural tube defects. While a recent report suggests that metformin may not activate fetal AMPK, which is reassuring, studies in pregnant woman with gestational diabetes and type 2 diabetes, which are ongoing, require completion before we can conclude that its use in pregnancy is safe. Furthermore, follow-up of the offspring will be critical to determine whether such treatment decreases or increases the development of obesity and diabetes.

Berberine as a therapy for type 2 diabetes and its complications: From mechanism of action to clinical studies

The incidence of type 2 diabetes is increasing rapidly worldwide, and the development of novel anti-diabetic drugs is emerging. However, most anti-diabetic drugs cannot be used in patients with hepatic dysfunction, renal disease, and heart disease, which makes pharmacological therapy of type 2 diabetes complicated. Despite continued introduction of novel agents, the search for an ideal drug that is useful as both a hypoglycemic agent and to reduce diabetes-related complications remains elusive. Berberine is an isoquinoline alkaloid extract that has shown promise as a hypoglycemic agent in the management of diabetes in animal and human studies. Mechanistic studies have revealed beneficial effects of berberine on diabetes-related complications. Although there have been few clinical reports of the anti-diabetic effects of berberine, little documentation of adverse effects in humans positions it as a potential candidate drug to treat type 2 diabetes. In the present review, the anti-diabetic mechanism of berberine, its effect on diabetes-related complications, and its recent use in human clinical studies is highlighted. In addition, we summarize the different treatments for type 2 diabetes in adults and children.

Association between first-line monotherapy with sulphonylurea versus metformin and risk of all-cause mortality and cardiovascular events: a retrospective, observational study

AIMS

To evaluate the risk of all-cause mortality and major adverse cardiovascular events (MACE) for patients exposed to first-line monotherapy with sulphonylurea or metformin.

METHODS

Data were from the Clinical Practice Research Datalink (CPRD). Patients with type 2 diabetes were selected if initiated with metformin or sulphonylurea monotherapy as their first-line glucose-lowering regimen 2000-2012. The primary endpoint was all-cause mortality; the secondary endpoint was MACE (myocardial infarction or stroke). Times to endpoints were compared using Cox proportional hazards models. Additional analyses were performed on subsets matched directly on key characteristics and by propensity score.

RESULTS

In the main analysis, 76 811 patients were prescribed metformin monotherapy (mean follow-up 2.9 years) and 15 687 sulphonylurea monotherapy (mean follow-up 3.1 years). A total of 2604 patients were included in each arm of the directly matched cohorts and 8836 in the propensity-matched. With respect to all-cause mortality, using all three analytical approaches the hazard ratio (HR) was significantly increased for sulphonylurea compared with metformin: adjusted HR = 1.580 (95% CI 1.483-1.684) for the main analysis, 1.902 (1.733-2.088) for those matched on propensity score, and 1.272 (1.021-1.584) for the directly matched cohort analysis. For MACE, the respective HRs were 1.196 (1.090-1.313), 1.202 (1.001-1.442) and 0.814 (0.578-1.148), respectively.

CONCLUSIONS

All-cause mortality was significantly increased in patients prescribed sulphonylurea compared with metformin monotherapy. Whilst residual confounding and confounding by indication may remain, this study indicates that first-line treatment with sulphonylurea monotherapy should be reconsidered.

A justification for less restrictive guidelines on the use of metformin in stable chronic renal failure

AIM

The aim was to justify less restrictive use of metformin in stable chronic renal failure, because a literature review reveals metformin is associated with a significantly lower incidence of cardiovascular events and mortality compared with other hypoglycaemic agents, and metformin-associated lactic acidosis is rare and causation uncertain. Studies on intentional metformin overdose and metformin bioavailability, renal clearance and plasma metformin in renal impairment provide evidence in support of a less restrictive use of metformin.

METHODS

In metformin overdose (n = 22), lactic acidosis was not inevitable with a plasma metformin > 40 mg/l (therapeutic level c. 1 mg/l): Severe lactic acidosis (pH ≤ 7.21, plasma lactate ≥ 11 mmol/l, n = 8) did not occur unless plasma metformin was > 40 mg/l. Plasma lactate was a more consistent predictor of pH than plasma metformin, with plasma lactate ≤ 4.7 being associated with a pH ≥ 7.34. A likely 'safe' plasma lactate is < 3.5 mmol/l and plasma metformin < 10 mg/l.

RESULTS

Plasma metformin can be predicted from estimated glomerular filtration rate and metformin dose. Reported plasma metformin in renal failure was always less than predicted plasma metformin. Predicted plasma metformin (mg/l), with an estimated glomerular filtration rate of 30 ml/min and metformin 2000 mg/day was 6.8; an estimated glomerular filtration rate of 20 ml/min and metformin 1500 mg/day was 5.1; an estimated glomerular filtration rate of 10 ml/min and metformin 500 mg/day was 4.4.

CONCLUSION

Metformin accumulates in renal failure and, although accumulation does not always lead to lactic acidosis, dose modification to achieve a predicted plasma metformin < 10 mg/l is suggested. As plasma metformin is not routinely available, plasma lactate should be useful in monitoring the use of metformin in renal failure.

How are patients with type 2 diabetes and renal disease monitored and managed? Insights from the observational OREDIA study

Background and aim

Chronic kidney disease (CKD) is frequent in type 2 diabetes mellitus (T2DM), and therapeutic management of diabetes is more challenging in patients with renal impairment (RI). The place of metformin is of particular interest since most scientific societies now recommend using half the dosage in moderate RI and abstaining from use in severe RI, while the classic contraindication with RI has not been removed from the label. This study aimed to assess the therapeutic management, in particular the use of metformin, of T2DM patients with CKD in real life.

Methods

This was a French cross-sectional observational study: 3,704 patients with T2DM diagnosed for over 1 year and pharmacologically treated were recruited in two cohorts (two-thirds were considered to have renal disease [CKD patients] and one-third were not [non-CKD patients]) by 968 physicians (81% general practitioners) in 2012.

Results

CKD versus non-CKD patients were significantly older with longer diabetes history, more diabetic complications, and less strict glycemic control (mean glycated hemoglobin [HbA_1c] 7.5% versus 7.1%; 25% of CKD patients had HbA_1c ≥8% versus 15% of non-CKD patients). Fifteen percent of CKD patients had severe RI, and 66% moderate RI. Therapeutic management of T2DM was clearly distinct in CKD, with less use of metformin (62% versus 86%) but at similar mean daily doses (~2 g/d). Of patients with severe RI, 33% were still treated with metformin, at similar doses. For other oral anti-diabetics, a distinct pattern of use was seen across renal function (RF): use of sulfonylureas (32%, 31%, and 20% in normal RF, moderate RI, and severe RI, respectively) and DPP4-i (dipeptidyl peptidase-4 inhibitors) (41%, 36%, and 25%, respectively) decreased with RF, while that of glinides increased (8%, 14%, and 18%, respectively). CKD patients were more frequently treated with insulin (40% versus 16% of non-CKD patients), and use of insulin increased with deterioration of RF (19%, 39%, and 61% of patients with normal RF, moderate RI, and severe RI, respectively). Treatment was modified at the end of the study-visit in 34% of CKD patients, primarily to stop or reduce metformin. However, metformin was stopped in only 40% of the severe RI patients.

Conclusion

Despite a fairly good detection of CKD in patients with T2DM, RI was insufficiently taken into account for adjusting anti-diabetic treatment.

Metformin and other antidiabetic agents in renal failure patients

This review mainly focuses on metformin, and considers oral antidiabetic therapy in kidney transplant patients and the potential benefits and risks of antidiabetic agents other than metformin in patients with chronic kidney disease (CKD). In view of the debate concerning lactic acidosis associated with metformin, this review tries to solve a paradox: metformin should be prescribed more widely because of its beneficial effects, but also less widely because of the increasing prevalence of contraindications to metformin, such as reduced renal function. Lactic acidosis appears either as part of a number of clinical syndromes (i.e., unrelated to metformin), induced by metformin (involving an analysis of the drug's pharmacokinetics and mechanisms of action), or associated with metformin (a more complex situation, as lactic acidosis in a metformin-treated patient is not necessarily accompanied by metformin accumulation, nor does metformin accumulation necessarily lead to lactic acidosis). A critical analysis of guidelines and literature data on metformin therapy in patients with CKD is presented. Following the present focus on metformin, new paradoxical issues can be drawn up, in particular: (i) metformin is rarely the sole cause of lactic acidosis; (ii) lactic acidosis in patients receiving metformin therapy is erroneously still considered a single medical entity, as several different scenarios can be defined, with contrasting prognoses. The prognosis for severe lactic acidosis seems even better in metformin-treated patients than in non-metformin users.

Metformin--mode of action and clinical implications for diabetes and cancer

Metformin has been the mainstay of therapy for diabetes mellitus for many years; however, the mechanistic aspects of metformin action remained ill-defined. Recent advances revealed that this drug, in addition to its glucose-lowering action, might be promising for specifically targeting metabolic differences between normal and abnormal metabolic signalling. The knowledge gained from dissecting the principal mechanisms by which metformin works can help us to develop novel treatments. The centre of metformin's mechanism of action is the alteration of the energy metabolism of the cell. Metformin exerts its prevailing, glucose-lowering effect by inhibiting hepatic gluconeogenesis and opposing the action of glucagon. The inhibition of mitochondrial complex I results in defective cAMP and protein kinase A signalling in response to glucagon. Stimulation of 5'-AMP-activated protein kinase, although dispensable for the glucose-lowering effect of metformin, confers insulin sensitivity, mainly by modulating lipid metabolism. Metformin might influence tumourigenesis, both indirectly, through the systemic reduction of insulin levels, and directly, via the induction of energetic stress; however, these effects require further investigation. Here, we discuss the updated understanding of the antigluconeogenic action of metformin in the liver and the implications of the discoveries of metformin targets for the treatment of diabetes mellitus and cancer.

The Association between 25-Hydroxyvitamin D and Hemoglobin A1c Levels in Patients with Type 2 Diabetes and Stage 1-5 Chronic Kidney Disease

Aim. To examine the relationship between plasma 25-hydroxyvitamin D (25(OH)D) levels and blood hemoglobin A1c (HbA1c) levels in diabetic patients at various stages of chronic kidney disease (CKD). Methods. We screened for data collected between 2003 and 2012. The correlation between 25(OH)D and HbA1c levels was studied in patients categorized according to the severity of CKD and their vitamin D status. A multivariate linear regression model was used to determine whether 25(OH)D and HbA1c levels were independently associated after adjustment for a number of covariates (including erythrocyte metformin levels). Results. We identified 542 reports from 245 patients. The mean HbA1c value was 6.7 ± 1.0% in vitamin D sufficiency, 7.3 ± 1.5% in insufficiency, and 8.4 ± 2.0% in deficiency (P < 0.0001). There was a negative correlation between 25(OH)D and HbA1c levels for the population as a whole (r = -0.387, P < 0.0001) and in the CKD severity subgroups (r = -0.384, P < 0.0001 and r = -0.333, P < 0.0001 for CKD stages 1-3 and 4-5, resp.). In the multivariate analysis, the 25(OH)D level was the only factor associated with HbA1c (P < 0.0001). Conclusion. 25(OH)D levels were negatively correlated with HbA1c levels independently of study covariates.