Outcome of severe lactic acidosis associated with metformin accumulation

A case report of metformin-associated lactic acidosis

Key Clinical Message

Metformin-associated lactic acidosis is a rare but serious complication in patients with type 2 diabetes, especially those with multiple health conditions. Prompt recognition and treatment, including potential renal replacement therapy, are crucial for managing severe acidosis and improving patient outcomes.

Abstract

Metformin (MTF) is commonly prescribed as a first-line treatment for diabetes, effectively preventing microvascular and macrovascular complications. However, metformin-associated lactic acidosis is a rare yet severe complication, associated with a mortality rate of up to 50%. We encountered a case involving a 73-year-old woman with type 2 diabetes, mental illness, and hypothyroidism, who developed life-threatening lactic acidosis while on metformin therapy. Upon presenting to the emergency department with complaints of weakness, nausea, and decreased urination for 5 days, she also reported abdominal pain and shortness of breath. Hypotension was noted with a blood pressure of 80/50 mmHg. Initial laboratory results revealed severe acidosis, prompting discontinuation of MTF. Despite resuscitation efforts and vasopressor therapy, severe acidemia persisted, leading to the initiation of renal replacement therapy. Following treatment with continuous renal replacement therapy, her acidemia resolved, and she was discharged from the hospital on the sixth day without complications, with normal kidney function.

Reversible acute blindness in suspected metformin-associated lactic acidosis: a case report

BACKGROUND

Metformin is commonly used for the treatment of type 2 diabetes mellitus. Its multiple advantages include low risk of hypoglycemia, weight neutrality, low cost, and cardioprotective and anti-inflammatory effects. Renal insufficiency is one of the contraindications for its use. Inadvertent prescription in patients with renal insufficiency may lead to metformin-associated lactic acidosis, which brings a high risk of mortality. The early recognition and management of metformin-associated lactic acidosis are essential.

CASE REPORT

We present the case of a 58-year-old Hui woman with a history of type 2 diabetes mellitus with nephropathy and heart disease for which she was treated with metformin, insulin, and heart medications. She developed nausea, vomiting, anion gap metabolic acidosis due to hyperlactatemia, and acute kidney injury. She was hospitalized to receive intravenous hydration and correction of metabolic acidosis after she suddenly developed blindness. The diagnostic workup ruled out central causes and her symptoms resolved briefly after continuous venovenous hemodialysis was initiated, confirming the diagnosis of metformin-associated lactic acidosis.

CONCLUSIONS

Metabolic disruption can cause acute blindness. Metabolic acidosis in a patient with a history of metformin intake should suggest the possibility of metformin-associated lactic acidosis, which must be treated immediately, without waiting for the results of other examinations, especially in patients with sudden blindness. Further study of reversible blindness-associated severe metabolic acidosis is needed.

Hypoglycemia-Induced Basal Ganglia Infarct: A Rare Case of Metformin Toxicity in a Hemodialysis Patient

Metformin is the preferred agent in type 2 diabetes due to its efficacy, safety profile, cardioprotective benefits, weight loss, and accessibility in the market. However, Metformin should be prescribed with caution in patients with renal dysfunction and is contraindicated in those with a glomerular filtration rate (GFR) of less than 30 mL/min. Though extremely rare, accumulation of metformin due to poor renal clearance can cause metformin toxicity and subsequently cause lactic acidosis and hypoglycemia. The incidence is estimated at less than 10 events per 100,000 patients. Hypoglycemia has been shown to induce ischemic strokes in previous case reports; however, only one other case control study has shown hypoglycemia-induced strokes in the setting of metformin toxicity. Herein, we present a rare case of hypoglycemia-induced ischemic stroke from metformin toxicity, in a patient undergoing maintenance hemodialysis. Our case report illustrates an extremely rare case of metformin toxicity that caused a hypoglycemic-induced ischemic infarct.

Relationship between metformin use and lactic acidosis in advanced chronic kidney disease: The REMIND-TMU study

BACKGROUND

Evidence of metformin-associated lactic acidosis (MALA) in advanced chronic kidney disease (CKD) has been limited due to high mortality rate but rare incidence rate. The mechanism of increased MALA in advanced CKD is mainly based on the hypothesis of decreased drug elimination, which might also be confounded by increased comorbidities as CKD progresses. The goal of the study is to analyze the incidence and associated factors of lactic acidosis between metformin user and non-user with advanced CKD.

METHODS

This study used a three million population-based, propensity score-matched cohort from 2008 to 2016. The primary outcome was laboratory-defined lactic acidosis. Relationships between the probability of lactic acidosis and various estimated glomerular filtration rate (eGFR) values in advanced CKD patients were also presented in regression analysis.

RESULTS

Adults with type 2 diabetes whose eGFR was <30 mL/min/1.73 m² were enrolled in this study. After the process of propensity score matching, 7707 patients were divided into metformin and non-metformin groups. In linear regression model, metformin significantly increased the risk of lactic acidosis (p=0.0204) as the eGFR declined in advanced CKD over a mean follow up of over 600 days even after confounder adjustment with age, sex and comorbidities.

CONCLUSIONS

Metformin was associated with a significant increased risk of laboratory-defined lactic acidosis (p=0.0204) even after adjusting confounder such as age, sex and underlying comorbidities. This "REMIND" study reminds us that metformin-associated lactic acidosis is mainly caused by decreased drug renal elimination other than underlying comorbidities in advanced CKD patients.

Metformin toxicity: A meta-summary of case reports

BACKGROUND

Metformin is arguably the most commonly prescribed oral hypoglycemic agent for the management of diabetes. Due to the lack of randomized control trials, most of the data pertaining to the clinical course, therapeutic interventions and outcomes of patients with metformin induced toxicity has come from case reports or series.

AIM

To analyse the symptomology, clinical interventions and outcomes of patients presenting with severe metformin toxicity by reviewing the published case reports and series.

METHODS

We performed a systematic search from PubMed, Science Direct, Reference Citation Analysis (https://www.referencecitationanalysis.com/) and Google Scholar databases using the terms “metformin” AND “toxicity” OR “overdose” OR “lactic acidosis” OR “hyperlactatemia”. The inclusion criteria were: (1) Case reports or case series with individual patient details; and (2) Reported toxicity or overdose of metformin in adults, published in the English language. Data regarding baseline demographics, clinical presentation, therapeutic interventions, intensive care unit course and overall outcome were collected.

RESULTS

Two hundred forty-two individual cases were analysed, from 158 case reports and 26 case series, with a cumulative mortality of 19.8%. 214 (88.4%) patients were diabetics on metformin. 57 (23.6%) had acute ingestion, but a great majority (76.4%) were on metformin in therapeutic doses when they developed toxicity. Metformin associated lactic acidosis (MALA) was the most commonly reported adverse effect present in 224 (92.6%) patients. Most of the patients presented with gastrointestinal and neurological symptoms and a significant number of patients had severe metabolic acidosis and hyperlactatemia. The organ support used was renal replacement therapy (RRT) (68.6%), vaso-pressors (58.7%) and invasive mechanical ventilation (52.9%). A majority of patients (68.6%) received RRT for toxin removal, renal dysfunction and correction of MALA. Patients with lowest pH and highest serum lactate and metformin levels also had favourable outcomes with use of RRT.

CONCLUSION

Most of the reported cases were on therapeutic doses of metformin but developed toxicity after an acute deterioration in renal functions. These patients may develop severe lactic acidosis, leading to significant morbidity and need for organ support. Despite severe MALA and the need for multiple organ support, they may have good outcomes, especially when RRT is used. The dose of metformin, serum pH, lactate and metformin levels may indicate the severity of toxicity and the need for aggressive therapeutic measures but may not necessarily indicate poor outcomes.

Association of Preadmission Metformin Use and Prognosis in Patients With Sepsis and Diabetes Mellitus: A Systematic Review and Meta-Analysis

BACKGROUND AND AIM

A growing body of evidence suggests that preadmission metformin use could decrease the mortality of septic patients with diabetes mellitus (DM); however, the findings remain controversial. Therefore, this meta-analysis was conducted on available studies to confirm the relationship between preadmission metformin use and mortality in patients with sepsis and DM.

METHODS

A comprehensive search of the PubMed, Embase, and Cochrane Library databases was performed for studies published before August 8, 2021. Observational studies assessing the correlation between metformin use and mortality in patients with sepsis and DM were considered eligible studies. We used the Newcastle-Ottawa Scale (NOS) to assess the outcome quality of each included article. Furthermore, the odds ratios (ORs) and 95% confidence intervals (CIs) were analyzed using the inverse variance method with random effects modeling.

RESULTS

Eleven articles including 8195 patients were analyzed in this meta-analysis. All the included articles were scored as low risk of bias. Our results showed that preadmission metformin use had a lower mortality rate (OR, 0.74; 95% CIs, 0.62-0.88, P < 0.01) in patients with sepsis and DM. Surprisingly, there was no statistically significant difference in the levels of serum creatinine (weighted mean difference (WMD), 0.36; 95% CIs, -0.03-0.75; P = 0.84) and lactic acid (WMD, -0.16; 95% CIs, -0.49-0.18; P = 0.07) between preadmission metformin use and non-metformin use.

CONCLUSIONS

This study is the most comprehensive meta-analysis at present, which shows that preadmission metformin use may reduce mortality and not increase the levels of serum creatinine and lactic acid in adult patients with sepsis and DM. Therefore, these data suggest that the potential efficacy of metformin could be assessed in future clinical studies.

SYSTEMATIC REVIEW REGISTRATION

https://inplasy.com/?s=INPLASY2021100113, identifier INPLASY2021100113.

Identifying patients with metformin associated lactic acidosis in the emergency department

Background Metformin associated lactic acidosis (MALA) is a serious adverse event with a high mortality rate of 30-50%. Early recognition of MALA and timely starting treatment may reduce its morbidity and mortality. Objective The aim of this study was to explore clinical parameters to identify patients with MALA in patients with suspected sepsis induced lactic acidosis in the emergency department ED. Setting A retrospective single centre study was conducted at the Deventer Teaching Hospital in the Netherlands. Method Patients with lactate concentration > 4.0 mmol/l admitted at the ED between 2010 and 2017 with suspected sepsis or confirmed MALA and referred to the Intensive Care Unit were included. Baseline characteristics (pH, lactate, creatinine and CRP) of MALA patients were compared with patients with suspected sepsis induced lactic acidosis. Creatinine and lactate concentration were selected as potential relevant parameters. Main outcome measure Sensitivity and specificity of the highest tertiles of the creatinine and the lactate concentrations separately, in combination, and both combined with metformin use, were calculated. Results Thirteen MALA and 90 suspected sepsis induced lactic acidosis patients were included. Lactate (14.7 vs 5.9 mmol/l, p < 0.01) and creatinine concentration (642 vs 174 μmol/l, p < 0.01) were significantly higher in the MALA group and arterial pH (7.04 vs 7.38, p < 0.01) and CRP (90 vs 185 mg/l, p < 0.01) were significantly lower. The combined parameters lactate ≥ 8.4 mmol/l, creatinine ≥ 256 μmol/l had a sensitivity of 85% and a specificity of 95% for identifying MALA in suspected sepsis induced lactic acidosis patients in the ED. When combined with metformin use the specificity increased to 99%. Conclusion When managing lactic acidosis in the ED the diagnosis MALA should be considered in patients with a creatinine concentration ≥ 256 μmol/l and lactate concentration ≥ 8.4 mmol/l.

Metformin-Associated Lactic Acidosis Developed as a Result of a Suicidal Attempt

Metformin is a biguanide group drug commonly used in the treatment of Type 2 DM. Even though Metformin- Associated Lactic Acidosis (MALA) is not seen very frequently, MALA has a high mortality rate. This case is presented to draw attention to efficiency of hemodialysis and CVVHDF tin the treatment of MALA.

A 25-year-old female patient was brought to the emergency service with abdominal pain and confusion. In her detailed history, it was learned that she took 100 tablets of metformin (1000 mg per tablet). Hemodialysis initiated because of severe metabolic acidosis, elevation of blood urea and hyperkalemia were seen in laboratory results. After that, patient was intubated because of low Glasgow Coma Scale (GCS:3) and vasopressor agent were started due to hypotension. In the intensive care unit, blood glucose was seen 44 mg dl^-1 and treated with 10% dextrose solution. CVVHDF treatment was started because of anuria and metabolic acidosis. Patient who underwent CVVHDF treatment for 12-days transferred to nephrology service on the 23^rd day of the ICU admission with full consciousness and stabilized vitals.

In conclusion, hemodialysis and CVVHDF should be the first treatment methods to be considered in patients with metformin-associated lactic acidosis. Renal replacement therapies, initiated rapidly and maintained for an adequate time period are promising in this high mortality rate cases.

Do Patients Die with or from Metformin-Associated Lactic Acidosis (MALA)? Systematic Review and Meta-analysis of pH and Lactate as Predictors of Mortality in MALA

OBJECTIVES

Metformin-associated lactic acidosis (MALA) may occur after acute metformin overdose, or from therapeutic use in patients with renal compromise. The mortality is high, historically 50% and more recently 25%. In many disease states, lactate concentration is strongly associated with mortality. The aim of this systematic review and meta-analysis is to investigate the utility of pH and lactate concentration in predicting mortality in patients with MALA.

METHODS

We searched PubMed, EMBASE, and Web of Science from their inception to April 2019 for case reports, case series, prospective, and retrospective studies investigating mortality in patients with MALA. Cases and studies were reviewed by all authors and included if they reported data on pH, lactate, and outcome. Where necessary, authors of studies were contacted for patient-level data. Receiver operating characteristic (ROC) curves were generated for pH and lactate for predicting mortality in patients with MALA.

RESULTS

Forty-four studies were included encompassing 170 cases of MALA with median age of 68.5 years old. Median pH and lactate were 7.02 mmol/L and 14.45 mmol/L, respectively. Overall mortality was 36.2% (95% CI 29.6-43.94). Neither lactate nor pH was a good predictor of mortality among patients with MALA. The area under the ROC curve for lactate and pH were 0.59 (0.51-0.68) and 0.43 (0.34-0.52), respectively.

CONCLUSION

Our review found higher mortality from MALA than seen in recent studies. This may be due to variation in standard medical practice both geographically and across the study interval, sample size, misidentification of MALA for another disease process and vice versa, confounding by selection and reporting biases, and treatment intensity (e.g., hemodialysis) influenced by degree of pH and lactate derangement. The ROC curves showed poor predictive power of either lactate or pH for mortality in MALA. With the exception of patients with acute metformin overdose, patients with MALA usually have coexisting precipitating illnesses such as sepsis or renal failure, though lactate from MALA is generally higher than would be considered survivable for those disease states on their own. It is possible that mortality is more related to that coexisting illness than MALA itself, and many patients die with MALA rather than from MALA. Additional work looking solely at MALA in healthy patients with acute metformin overdose may show a closer relationship between lactate, pH, and mortality.

Extracorporeal treatment of metforminassociated lactic acidosis in clinical practice: a retrospective cohort study

Purpose

To assess whether extracorporeal treatment (ECTR) improves outcome of patients with metformin-associated lactic acidosis (MALA) and to evaluate the clinical applicability of the Extracorporeal Treatments in Poisoning Workgroup (EXTRIP) criteria for starting ECTR in metformin poisoning.

Methods

Patients with metformin serum concentrations above 2 mg/l who were admitted in the Deventer Teaching Hospital between January 2000 and July 2019 and complied with the definition of MALA (pH < 7.35 and lactate concentration > 5 mmol/l) were included. Mortality and clinical parameters of patients treated with ECTR or not were compared. In addition, treatment of MALA in clinical practice was verified against the criteria of EXTRIP.

Results

Forty-two patients were included. Lactate (13.8 versus 10.5 mmol/l, p = 0.01), creatinine (575 versus 254 umol/l, p < 0.01)), metformin (29.4 versus 8.6 mg/l, p < 0.01) concentrations, and vasopressor requirement (72% versus 23%, p < 0.01) were significantly higher in the ECTR-group. Blood pH (7.05 versus 7.19, p = 0.03) and bicarbonate (6 versus 11 mmol/l, p < 0.01) were significantly lower. Mortality, length of hospital stay, and mechanical ventilation requirement were not statistically different. In 83% of patients, treatment of MALA was in accordance with the EXTRIP criteria.

Conclusions

Although there was no statistical benefit in mortality shown from ECTR, ECTR might be lifesaving in MALA, considering the ECTR-group was significantly sicker than the non-ECTR-group.

The majority of patients were treated in line with the EXTRIP criteria. Severity of lactic acidosis and renal impairment were the main indications for initiating ECTR.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02857-5) contains supplementary material, which is available to authorized users.

The Association of Premorbid Metformin Exposure With Mortality and Organ Dysfunction in Sepsis: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

To examine the association between premorbid metformin exposure and mortality, hyperlactatemia, and organ dysfunction in sepsis.

Incidence and risk factors for hyperlactatemia in ED patients with acute metformin overdose

INTRODUCTION

The goals of this study are to describe clinical characteristics and risk factors for metabolic acidosis with hyperlactatemia in emergency department (ED) patients with acute metformin overdose.

METHODS

This was a secondary analysis of data from a retrospective observational cohort of adult ED patients presenting with acute drug overdose at two tertiary care hospitals over 5 years. The primary outcomes were: (1) hyperlactatemia, defined as a lactate concentration ≥ 2 mmol/L at any point during hospital admission and, (2) metformin associated lactic acidosis (MALA), defined as a lactate concentration ≥ 5 mmol/L and pH <7.35 at any point during hospital admission.

RESULTS

We screened 3739 acute overdoses; 2872 met eligibility, 56 self-reported metformin overdose (57% female, mean age 55.8). Of these, 39 had measured lactate values. There was a high incidence of hyperlactatemia (56.4%); MALA was less frequent (17.9%). There were no deaths. Low serum bicarbonate was an independent clinical risk factor for hyperlactatemia (adjusted p < 0.05). Acetaminophen co-exposure was an independent clinical risk factor for MALA (OR 24.40, 95% CI 1.6-376.4).

CONCLUSIONS

In ED patients with acute metformin overdose, initial hyperlactatemia is common but MALA is unusual. Acetaminophen co-exposure is a novel independent risk factor for the occurrence of MALA that deserves further investigation.

Intoxication à la metformine

La metformine, seul représentant disponible en France de la classe des biguanides, est un médicament antidiabétique largement prescrit. L’effet thérapeutique bénéfique du contrôle glycémique obtenu par inhibition de la néoglucogenèse est objectivé par une réduction de la morbimortalité chez les patients diabétiques de type 2. Néanmoins, la metformine affecte aussi le métabolisme du lactate en augmentant sa production par la cellule. Ainsi, l’effet secondaire le plus redouté est l’acidose lactique associée à la metformine (metformin-associated lactic acidosis [MALA]). Celle-ci est liée à une augmentation brutale de la concentration en metformine dans le sang et dans les tissus, que ce soit après ingestion d’une grande quantité de médicament ou plus souvent dans les suites d’une insuffisance rénale aiguë chez un patient traité au long cours. Dans ce contexte d’acidose métabolique majeure avec hyperlactatémie, la sévérité des défaillances d’organes conditionne le pronostic. La prise en charge thérapeutique est symptomatique avec recours précoce à une épuration extrarénale dans les formes sévères ou ne répondant pas au traitement initial. La prévention de la MALA repose avant tout sur le respect des contreindications de la metformine chez les patients diabétiques.

Reversible Acute Blindness in Suspected Metformin-Associated Lactic Acidosis

BACKGROUND

Metformin is commonly used for the treatment of type 2 diabetes mellitus. Renal insufficiency is one of the contraindications for its use. Inadvertent prescription in patients with renal insufficiency may lead to metformin-associated lactic acidosis (MALA), which is associated with a high risk of mortality. Consequently, the early recognition and management of MALA is essential.

CASE REPORT

We present the case of a 68-year-old man who had reversible blindness resulting from severe lactic acidosis. On presentation, he was alert, oriented, and had no complaints except mild abdominal discomfort and blindness. He denied any history of trauma or drug abuse. The results of the laboratory studies showed severe metabolic acidosis with a high anion gap and increased levels of serum creatinine. There were no predisposing ocular or neurologic lesions that could have induced the blindness. Although the blood levels of methanol, ethanol, and metformin were not estimated, correction of acidosis and hemodialysis led to a complete recovery. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Rarely, transient blindness may occur in patients with fatal severe metabolic acidosis. Evaluation for the presence of metabolic acidosis and a detailed medical history are essential in the management of acute blindness in such patients.

Association of preadmission metformin use and mortality in patients with sepsis and diabetes mellitus: a systematic review and meta-analysis of cohort studies

Background

Recent studies have reported that preadmission metformin users had lower mortality than non-metformin users in patients with sepsis and diabetes mellitus; however, these results are still controversial. Therefore, we conducted a systematic review and meta-analysis of published observational cohort data to determine the association between preadmission metformin use and mortality in septic adult patients with diabetes mellitus.

Methods

The MEDLINE, EMBASE, and Cochrane CENTRAL databases were searched from their inception to September 30, 2018. Cohort studies that evaluated the use of metformin in septic adult patients with diabetes mellitus were included. The quality of outcomes was evaluated using the Newcastle-Ottawa Scale (NOS). The inverse variance method with random effects modelling was used to calculate the pooled odds ratios (ORs) and 95% CIs.

Results

Five observational cohort studies (1282 patients) that were all judged as having a low risk of bias were included. In this meta-analysis, metformin use was associated with a significantly lower mortality rate (OR, 0.59; 95% CI, 0.43–0.79, P = 0.001).

Conclusions

This meta-analysis indicated an association between metformin use prior to admission and lower mortality in septic adult patients with diabetes mellitus. This finding suggested that the possible effect of metformin should be evaluated in future clinical trials.

Metformin as a host-directed therapeutic in tuberculosis: Is there a promise?

To complement the development of new or repurposed drugs for improving the treatment outcomes of drug-susceptible and drug-resistant tuberculosis, current insight also focuses on the use of host-directed therapy. Metformin, a drug often used in the management of type 2 diabetes mellitus, has attracted attention by virtue of its favourable activity as an adjunctive agent against tuberculosis, discovered through laboratory and clinical studies. To definitively establish its role as a host-directed therapeutic in tuberculosis, more preclinical and clinical research is still required to better delineate its mechanism(s) of action and optimal clinical use.

Metformin-associated Severe Lactic Acidosis in the Setting of Acute Kidney Injury

Metformin is a first-line biguanide agent for the treatment of diabetes mellitus. It has been known to be associated with lactic acidosis. This side effect especially worsens when being used with other medications affecting the kidney such as angiotensin-converting enzyme inhibitors (ACEi) and loop diuretics. This is a case of a 63-year-old male who suffered from metformin-induced lactic acidosis and underwent hemodialysis for treatment.

Interaction of rs316019 variants of SLC22A2 with metformin and other drugs- an in silico analysis

Metformin is one of the first-line and most widely prescribed drugs to treat type 2 diabetes (T2D). Its clearance from circulation is mostly facilitated by SLC22A2 (OCT2) in the renal cells. SLC22A2 is a polyspecific organic cation transporter and mediate transport of structurally unrelated endogenous and exogenous compounds including many drugs. rs316019 (p.270A > S) is the most common variant of SLC22A2 with a frequency as high as 15% or more in many populations. The 270S form of SLC22A2 clears metformin from circulation at much reduced level compared to the 270A form. If accumulated, metformin increases plasma lactate level in a concentration-dependent manner which can lead to a condition known as metformin-associated lactic acidosis (MALA). MALA is a potentially life-threatening complication with a mortality rate of 30-50%. Pre-existing clinical conditions, such as renal impairment, sepsis, anoxia, etc may make individuals more prone to MALA. In this study, we used computational approaches to investigate the effect of 270A > S change in SLC22A2 on interaction with metformin and other drugs. Based on the structural models, all substrates bind to the same pocket of SLC22A2. The substrates fit better to the binding site of 270A form of SLC22A2. The binding site has a few core interacting residues, among which SER358 appears to be the most important. It is an in silico prediction that the T2D patients, who are under metformin regimen, should be cautious in taking ranitidine (an over-the-counter sold drug) on a regular basis as it may lead to metformin associated lactate accumulation in blood.

Risk of lactic acidosis in type 2 diabetes patients using metformin: A case control study

BACKGROUND

Metformin constitutes first-line treatment of type 2 diabetes mellitus. It is presumed to have lactic acidosis as a dangerous, but rare, side effect.

OBJECTIVES

To estimate the incidence rate of lactic acidosis in patients with type 2 diabetes mellitus as well as to estimate the relative risk of lactic acidosis associated with metformin treatment.

METHODS

This is a population-based combined cohort and case-control study among patients with type 2 diabetes mellitus who were acutely admitted with lactic acidosis at Odense University Hospital, Denmark; in the period from 1st June 2009 to 1st October 2013. The patients included as cases were all acutely hospitalized with lactic acidosis (pH <7.35 and lactate ≥2.0 mmol/l). For each case, we identified 24 age- and sex-matched controls sampled from the same cohort with type 2 diabetes mellitus. The use of metformin identified by using a prescription database. Analyses included multivariable logistic regression and adjusting for predefined confounding: renal function, HbA1c, comorbidity and diabetes duration.

RESULTS

Our cohort included 10,652 patients with type 2 diabetes mellitus with a median age of 74 years, and 51.5% were male. During follow-up, 163 individuals were hospitalized with lactic acidosis, corresponding to an incidence rate of 391/100,000 person years. Use of metformin was not associated with lactic acidosis: adjusted odds ratio was 0.79 (95%CI 0.54-1.17).

CONCLUSION

Among patients with type 2 diabetes mellitus, the incidence rate of acute hospitalization with lactic acidosis was 391/100,000 person years. Use of metformin did not increase the risk of lactic acidosis. However, comorbidity seems to be an important risk factor.

Metformin-Associated Lactic Acidosis: A Case Report

A 54-year-old woman with type 2 diabetes mellitus, hypertension, and peripheral vascular disease developed life-threatening lactic acidosis during treatment with metformin for type 2 diabetes. The woman received metformin at 1000 mg orally twice a day for type 2 diabetes. She presented to our emergency department with a 3-day history of severe watery diarrhea, nausea, and vomiting. Her grandson whom she cared for had gastroenteritis several days prior to the onset of her symptoms. She was confused and hypotensive with a blood pressure of 70/39 mmHg. Her initial laboratory findings were remarkable with an arterial blood gas pH 6.57, HCO[Formula: see text] 2 mEq/L, anion gap 30 mmol/L, and lactate 16.3 mmol/L. She was diagnosed with severe lactic acidosis. Metformin was discontinued. Upon arrival in the emergency department, she became unresponsive and experienced a pulseless electrical activity cardiac arrest. After resuscitation, her severe acidemia persisted despite aggressive intervention with volume resuscitation and vasopressors, leading to the initiation of renal replacement therapy. After multiple dialysis treatments, her severe acidemia resolved. Serum metformin concentration from presentation ultimately returned to 42 mcg/mL (therapeutic concentration: 1-2 mcg/mL). She was discharged from the hospital on day 15 without any neurologic complications. A Naranjo assessment score of 8 was obtained, indicating a probable relationship between the patient's lactic acidosis and her use of the suspect drug.

Metformin-Associated Lactic Acidosis Undergoing Renal Replacement Therapy in Intensive Care Units: A Five-Million Population-Based Study in the North-West of Italy

BACKGROUND

Metformin-associated lactic acidosis (MALA) is a severe complication of drug administration with significant morbidity and mortality. So far no study in large population areas have examined the incidence, clinical profile and outcome of acute kidney injury (AKI)-MALA patients admitted in intensive care units (ICUs) and treated by renal replacement therapy (MALA-RRT).

METHODS

Retrospective analysis over a 6-year period (2010-2015) in Piedmont and Aosta Valley regions (5,305,940 inhabitants, 141,174 diabetics treated with metformin) of all MALA-RRT cases.

RESULTS

One hundred and seventeen cases of AKI-MALA-RRT were observed (12.04/100,000 metformin treated diabetics, 1.45% of all RRT-ICU patients). Survival rate was 78.3%. The average duration of RRT was 4.0 days at mean dialysis effluent of 977 mL/kg/day. At admission most patients were dehydrated, and experienced shock and oliguria.

CONCLUSION

Our data showed that MALA-RRT is a common complication, needing more prevention. Adopted policy of early, extended, continuous and high efficiency dialysis could contribute to an observed high survival rate. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=471917.

METFORMIN: NONGLYCEMIC EFFECTS AND POTENTIAL NOVEL INDICATIONS

OBJECTIVE

Metformin is the most commonly prescribed drug for the treatment of type 2 diabetes because of its apparent robust effects in reducing cardiovascular risk. This review examines the current literature regarding the nonglycemic effects and potential novel indications for metformin.

METHODS

Review of the literature, with a focus on metformin use in Stage 3 chronic kidney disease (CKD-3) and heart failure (HF).

RESULTS

The United Kingdom Prospective Diabetes Study suggests that metformin reduces the risk of myocardial infarction, and more recent retrospective studies have shown an association between metformin use and a reduction in stroke, atrial fibrillation and all-cause mortality. The mechanism(s) explaining these putative benefits are not clear but may involve decreased energy intake (with attendant weight loss), improvement in lipids, and lowering of blood pressure; a literature review suggests that metformin lowers blood pressure when it is elevated, but not when it is normal. Metformin appears to be safe when given to patients with CKD-3. In addition, there is evidence that individuals with CKD-3, who are at increased cardiovascular risk, stand to benefit from metformin therapy. Lactic acidosis is an extremely remote and probably avoidable risk; measurement of plasma metformin levels and more frequent monitoring of renal function may be useful in selected patients with CKD-3 who are treated with metformin. Finally, there is evidence that metformin is safe in patients with HF; metformin therapy is associated with a reduction in newly incident HF and in HF mortality.

CONCLUSION

Metformin has a dominant position in the treatment of type 2 diabetes that is deserved due to its favorable and robust effects on cardiovascular risk.

ABBREVIATIONS

AMP = adenosine monophosphate BP = blood pressure CKD = chronic kidney disease CKD-3 = Stage 3 CKD eGFR = estimated glomerular filtration rate HDL = high-density lipoprotein HF = heart failure MAP = mean arterial pressure mVO2 = myocardial oxygen consumption T2DM = type 2 diabetes mellitus UKPDS = United Kingdom Prospective Diabetes Study.

Effect of prescribing metformin according to eGFR instead of serum creatinine level: A study based on Korean National Health and Nutrition Examination Survey (KNHANES) 2009-2014

BACKGROUND

The metformin label has recently been changed from serum creatinine (sCr)-based to estimated glomerular filtration rate (eGFR)-based indication, which is expected to expand its use for patients with mild renal insufficiency. However, because the sCr level is lower in Asians than in Caucasians at the same level of renal function, this change might not expand metformin use in the Asian population. We investigated the effect of this change among Korean patients with diabetes.

METHODS

Data from the Korean National Health and Nutrition Examination Survey 2009 to 2014 were used and included 4,127 adult patients with diabetes. The metformin eligibility was assessed by the sCr level (1.4 mg/dL for women and 1.5 mg/dL for men) or by eGFR categories (contraindicated, <30; indeterminate, ≥30, <45; likely safe, ≥45 mL/min/1.73 m2) calculated by various eGFR equations including MDRD equation. We designated the 'expanding' and 'contracting' population as those who are likely safe according to eGFR among sCr-ineligible patients and those contraindicated according to eGFR among sCr-eligible patients, respectively. Results were weighted to the whole Korean adult population.

RESULTS

All eGFR equations showed expansion in the population for whom metformin is likely safe, ranging from 14.3% to 19.9% of the sCr-ineligible population. With the MDRD equation, the expanding population was 15,264 (15.8%) and the contracting population was 0 (0.0%). Male sex and younger age were significantly associated with the expanding population.

CONCLUSIONS

Contrary to our concern, prescribing metformin according to eGFR substantially expanded the indication of its use among the Korean diabetic patients.

Investigation of Risk Factors Affecting Lactate Levels in Japanese Patients Treated with Metformin

Metformin is a biguanaide antidiabetic drug used worldwide, and its effectiveness and benefits have already been established. However, the safety of high doses of metformin in Japanese patients, especially in elderly patients with a decreased renal function, remains unclear. Among the side effects of metformin, lactate acidosis is the most problematic due to a high mortality rate. Therefore, we assessed plasma lactate levels in metformin-treated patients to identify independent risk factors for hyperlactemia. 290 outpatients receiving various doses of metformin at our hospital were enrolled between March and July 2014. Serum electrolytes, Cre (creatinine), BUN (blood urea nitrogen), UA (uric acid), HbA1c (hemoglobin A1c), and lactate levels were investigated. Lactate levels did not significantly differ between the elderly (≥75 years) and non-elderly (<75 years) groups. Patients in the elderly group had a significantly lower daily metformin dose and estimated glomerular filtration rate (eGFR), compared with the non-elderly group (both p<0.005). Between with and without hyperlactemia groups, no significant differences were observed in either Cre or age. On the other hand, patients with hyperlactemia had a significantly higher dose of metformin than those without hyperlactemia (p<0.05). In this study, we found that old age and mildly impaired kidney function were not associated with increased lactate levels, and that a higher dose of metformin may be an independent risk factor for elevated lactate levels in Japanese patients.

A case of type 2 diabetes mellitus with metformin-associated lactic acidosis initially presenting the appearance of a sulfonylurea-related hypoglycemic attack

Case

A 64‐year‐old Japanese woman with diabetes mellitus was admitted for hypoglycemia. Her diabetes had been under good control with glimepiride, voglibose, exenatide, and metformin for a few years. Although overt proteinuria was observed, the serum creatinine values were within normal range during the routine outpatient follow‐up. Hypoglycemic attack caused by glimepiride and loss of appetite by urinary tract infection were diagnosed. Then, metformin‐associated lactic acidosis with acute renal failure caused by dehydration was detected.

Outcome

Her condition was improved by continuous veno‐venous hemodiafiltration and hemodialysis, known to be useful to remove metformin.

Conclusion

We reported a case of metformin‐associated lactic acidosis with hypoglycemia during routine treatment of diabetes that was successfully rescued by early renal replacement therapy.

Should Restrictions Be Relaxed for Metformin Use in Chronic Kidney Disease? No, We Should Never Again Compromise Safety!

Metformin is and has been considered as first-line therapy for type 2 diabetes for over a quarter of a century. Like other biguanides, metformin can cause a lactic acidosis that is exceptionally rare but fatal. The likelihood of metformin-associated lactic acidosis is substantially higher in patients with kidney impairment and also among those with seemingly normal kidney function who are at risk of acute kidney injury (AKI). Hence, regulatory agencies in many industrialized nations have maintained strict renal restrictions surrounding metformin. However, there have been millions of people exposed to metformin for many years, many of them with serum creatinine values at or close to 1.5 mg/dL with estimated glomerular filtration rates (eGFRs) much below 60 mL/min/1.73 m(2) who have not developed lactic acidosis. Thus, there clearly remains controversy in this area, and there has been heightened pressure to remove the renal restrictions of metformin. To provide a discussion on the pros and cons of relaxing the renal restrictions for metformin use, we provide a Point-Counterpoint. In the point narrative below, Drs. Kalantar-Zadeh and Kovesdy provide their argument that although there is little evidence of the potential benefits of metformin in kidney disease, just considering the sheer numbers of metformin users and the high fatality rate of its associated lactic acidosis, the most appropriate practice is to avoid metformin use in people with eGFR <45 mL/min/1.73 m(2) or in those who are at high risk of AKI irrespective of underlying eGFR. In the following counterpoint narrative, Drs. Bakris and Molitch argue that the data from a very large analysis demonstrate clearly that serum creatinine should be supplanted with eGFR as the criteria for metformin use and that the incidence of lactic acidosis is only elevated in those with a reduced eGFR who become dehydrated for various reasons or in those exposed to some toxin resulting in AKI. Otherwise the data clearly support the use of metformin under normal circumstances down to eGFR >30 mL/min/1.73 m(2)-William T. CefaluEditor in Chief, Diabetes Care.

Should Restrictions Be Relaxed for Metformin Use in Chronic Kidney Disease? Yes, They Should Be Relaxed! What's the Fuss?

Metformin is and has been considered as first-line therapy for type 2 diabetes for over a quarter of a century. Like other biguanides, metformin can cause a lactic acidosis that is exceptionally rare but fatal. The likelihood of metformin-associated lactic acidosis is substantially higher in patients with kidney impairment and also among those with seemingly normal kidney function who are at risk of acute kidney injury (AKI). Hence, regulatory agencies in many industrialized nations have maintained strict renal restrictions surrounding metformin. However, there have been millions of people exposed to metformin for many years, many of them with serum creatinine values at or close to 1.5 mg/dL with estimated glomerular filtration rates (eGFRs) much below 60 mL/min/1.73 m(2) who have not developed lactic acidosis. Thus, there clearly remains controversy in this area, and there has been heightened pressure to remove the renal restrictions of metformin. To provide a discussion on the pros and cons of relaxing the renal restrictions for metformin use, we provide a Point-Counterpoint. In the preceding point narrative, Drs. Kalantar-Zadeh and Kovesdy provide their argument that although there is little evidence of the potential benefits of metformin in kidney disease, just considering the sheer numbers of metformin users and the high fatality rate of its associated lactic acidosis, the most appropriate practice is to avoid metformin use in people with eGFR <45 mL/min/1.73 m(2) or in those who are at high risk of AKI irrespective of underlying eGFR. In the counterpoint narrative below, Drs. Bakris and Molitch argue that the data from a very large analysis demonstrate clearly that serum creatinine should be supplanted with eGFR as the criteria for metformin use and that the incidence of lactic acidosis is only elevated in those with a reduced eGFR who become dehydrated for various reasons or in those exposed to some toxin resulting in AKI. Otherwise the data clearly support the use of metformin under normal circumstances down to eGFR >30 mL/min/1.73 m(2)-William T. CefaluEditor in Chief, Diabetes Care.

Metformin-associated lactic acidosis: Current perspectives on causes and risk

Although metformin has become a drug of choice for the treatment of type 2 diabetes mellitus, some patients may not receive it owing to the risk of lactic acidosis. Metformin, along with other drugs in the biguanide class, increases plasma lactate levels in a plasma concentration-dependent manner by inhibiting mitochondrial respiration predominantly in the liver. Elevated plasma metformin concentrations (as occur in individuals with renal impairment) and a secondary event or condition that further disrupts lactate production or clearance (e.g., cirrhosis, sepsis, or hypoperfusion), are typically necessary to cause metformin-associated lactic acidosis (MALA). As these secondary events may be unpredictable and the mortality rate for MALA approaches 50%, metformin has been contraindicated in moderate and severe renal impairment since its FDA approval in patients with normal renal function or mild renal insufficiency to minimize the potential for toxic metformin levels and MALA. However, the reported incidence of lactic acidosis in clinical practice has proved to be very low (<10 cases per 100,000 patient-years). Several groups have suggested that current renal function cutoffs for metformin are too conservative, thus depriving a substantial number of type 2 diabetes patients from the potential benefit of metformin therapy. On the other hand, the success of metformin as the first-line diabetes therapy may be a direct consequence of conservative labeling, the absence of which could have led to excess patient risk and eventual withdrawal from the market, as happened with earlier biguanide therapies. An investigational delayed-release metformin currently under development could potentially provide a treatment option for patients with renal impairment pending the results of future studies. This literature-based review provides an update on the impact of renal function and other conditions on metformin plasma levels and the risk of MALA in patients with type 2 diabetes.

Metformin-Associated Lactic Acidosis Presenting as Acute ST-Elevation Myocardial Infarction

BACKGROUND

Metformin-associated lactic acidosis (MALA) is a rare but life-threatening adverse drug reaction of metformin, the most frequently prescribed medication for patients with type 2 diabetes mellitus. The diagnosis of MALA is difficult to make because of diverse clinical presentations that can masquerade as other critical illnesses.

CASE REPORT

A 52-year-old woman presented with altered mental status, hypoglycemia, and shock. A prehospital electrocardiogram showed findings consistent with posterolateral ST-elevation myocardial infarction, and the cardiac catheterization laboratory was activated before patient arrival. On arrival to the emergency department, she was found to have severe metabolic derangements and hypothermia, and the catheterization laboratory was canceled. Aggressive supportive measures and emergent hemodialysis were instituted. A metformin concentration was sent from the ED and returned at 51 μg/mL (therapeutic range 1-2 μg/mL), making MALA the most likely diagnosis. She recovered after prolonged critical illness and was discharged in good condition. No alternate diagnoses were found despite extensive work-up. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Metformin is the most prescribed antidiabetic drug in the world. Although MALA is a rare complication, it is important for emergency physicians to keep MALA on the differential for diabetic patients presenting with severe metabolic acidosis.

Prognosis of patients presenting extreme acidosis (pH <7) on admission to intensive care unit

PURPOSE

The purpose was to determine prognosis of patients presenting extreme acidosis (pH <7) on admission to the intensive care unit (ICU) and to identify mortality risk factors.

MATERIALS AND METHODS

We retrospectively analyzed all patients who presented with extreme acidosis within 24 hours of admission to a polyvalent ICU in a university hospital between January 2011 and July 2013. Multivariate analysis and survival analysis were used.

RESULTS

Among the 2156 patients admitted, 77 patients (3.6%) presented extreme acidosis. Thirty (39%) patients suffered cardiac arrest before admission. Although the mortality rate predicted by severity score was 93.6%, death occurred in 52 cases (67.5%) in a median delay of 13 (5-27) hours. Mortality rate depended on reason for admission, varying between 22% for cases linked to diabetes mellitus and 100% for cases of mesenteric infarction (P = .002), cardiac arrest before admission (P < .001), type of lactic acidosis (P = .007), high Simplified Acute Physiology Score II (P = .008), and low serum creatinine (P = .012).

CONCLUSIONS

Patients with extreme acidosis on admission to ICU have a less severe than expected prognosis. Whereas mortality is almost 100% in cases of cardiac arrest before admission, mortality is much lower in the absence of cardiac arrest before admission, which justifies aggressive ICU therapies.

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.

Metformin-associated lactic acidosis

: Metformin is the most commonly prescribed oral antidiabetic agent. Despite a good safety profile in most patients with diabetes, the risk of metformin-associated lactic acidosis is real if safety guidelines are ignored. Experience with 3 cases of metformin-associated lactic acidosis is reported. Two cases were caused by inappropriate use of metformin in the presence of renal, cardiac and hepatic failure and 1 case followed an intentional overdose. The literature was reviewed on the clinical presentation, prevalence, pathogenesis, prognosis and management of metformin-associated lactic acidosis. This report highlights the importance of proper patient selection, clinical and laboratory monitoring and recommendation on when to stop the drug in ambulatory and hospitalized patients to prevent this unusual but potentially lethal complication.

[Metformin-induced lactic acidosis : Severe symptoms with difficult diagnostics]

Metformin-induced lactic acidosis is a rare but severe disease for the individual patients. A case of a 64-year-old patient with diabetes mellitus type 2 suffering from this disease is presented where metformin accumulation was caused by prerenal acute kidney failure. The clinical evaluation up to the final diagnosis, the pathophysiology and the appropriate therapy are presented in detail. Additionally, the current guidelines regarding the perioperative management of metformin administration are summarized. The case described aims to direct attention to the rare but, nevertheless, severe symptoms of metformin-induced lactic acidosis.

Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside

Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.

Metformin in patients with type 2 diabetes and kidney disease: a systematic review

IMPORTANCE

Metformin is widely viewed as the best initial pharmacological option to lower glucose concentrations in patients with type 2 diabetes mellitus. However, the drug is contraindicated in many individuals with impaired kidney function because of concerns of lactic acidosis.

OBJECTIVE

To assess the risk of lactic acidosis associated with metformin use in individuals with impaired kidney function.

EVIDENCE ACQUISITION

In July 2014, we searched the MEDLINE and Cochrane databases for English-language articles pertaining to metformin, kidney disease, and lactic acidosis in humans between 1950 and June 2014. We excluded reviews, letters, editorials, case reports, small case series, and manuscripts that did not directly pertain to the topic area or that met other exclusion criteria. Of an original 818 articles, 65 were included in this review, including pharmacokinetic/metabolic studies, large case series, retrospective studies, meta-analyses, and a clinical trial.

RESULTS

Although metformin is renally cleared, drug levels generally remain within the therapeutic range and lactate concentrations are not substantially increased when used in patients with mild to moderate chronic kidney disease (estimated glomerular filtration rates, 30-60 mL/min per 1.73 m2). The overall incidence of lactic acidosis in metformin users varies across studies from approximately 3 per 100,000 person-years to 10 per 100,000 person-years and is generally indistinguishable from the background rate in the overall population with diabetes. Data suggesting an increased risk of lactic acidosis in metformin-treated patients with chronic kidney disease are limited, and no randomized controlled trials have been conducted to test the safety of metformin in patients with significantly impaired kidney function. Population-based studies demonstrate that metformin may be prescribed counter to prevailing guidelines suggesting a renal risk in up to 1 in 4 patients with type 2 diabetes mellitus--use which, in most reports, has not been associated with increased rates of lactic acidosis. Observational studies suggest a potential benefit from metformin on macrovascular outcomes, even in patients with prevalent renal contraindications for its use.

CONCLUSIONS AND RELEVANCE

Available evidence supports cautious expansion of metformin use in patients with mild to moderate chronic kidney disease, as defined by estimated glomerular filtration rate, with appropriate dosage reductions and careful follow-up of kidney function.

Risk of lactic acidosis or elevated lactate concentrations in metformin users with renal impairment: a population-based cohort study

OBJECTIVE

The objective of this study was to determine whether treatment with metformin in patients with renal impairment is associated with a higher risk of lactic acidosis or elevated lactate concentrations compared with users of a noninsulin antidiabetic drug (NIAD) who had never used metformin.

RESEARCH DESIGN AND METHODS

A cohort of 223,968 metformin users and 34,571 diabetic patients who had never used metformin were identified from the Clinical Practice Research Datalink (CPRD).The primary outcome was defined as either a CPRD READ code lactic acidosis or a record of a plasma lactate concentration >5 mmol/L. The associations between renal impairment, dose of metformin, and the risk of lactic acidosis or elevated lactate concentrations were determined with time-dependent Cox models and expressed as hazard ratios (HRs).

RESULTS

The crude incidence of lactic acidosis or elevated lactate concentrations in current metformin users was 7.4 per 100,000 person-years (vs. 2.2 per 100,000 person-years in nonusers). Compared with nonusers, risk of lactic acidosis or elevated lactate concentrations in current metformin users was significantly associated with a renal function <60 mL/min/1.73 m(2) (adjusted HR 6.37 [95% CI 1.48-27.5]). The increased risk among patients with impaired renal function was further increased in users of ≥730 g of metformin in the preceding year (adjusted HR 11.8 [95% CI 2.27-61.5]) and in users of a recent high daily dose (>2 g) of metformin (adjusted HR 13.0 [95% CI 2.36-72.0]).

CONCLUSIONS

Our study is consistent with current recommendations that the renal function of metformin users should be adequately monitored and that the dose of metformin should be adjusted, if necessary, if renal function falls below 60 mL/min/1.73 m(2).