Metformin-associated lactic acidosis: predisposing factors and outcome

Metformin-associated lactic acidosis: a serious complication of a common drug

Metformin-associated lactic acidosis (MALA) is a rare and potentially life-threatening complication of metformin use. It typically occurs in patients who are diabetic and also have other risk factors for lactic acidosis, including kidney and liver conditions, malignancy, or use of certain medications. We report a case of MALA in a man in his 70s with diabetes who presented with gradually worsening gastrointestinal symptoms, including severe abdominal pain and nausea. He reported these symptoms in the setting of metformin use with an acute kidney injury (AKI), likely brought on by poor oral intake and excessive antibiotic use for a urinary tract infection. He was promptly started on intravenous fluids with a bicarbonate drip to concurrently treat his prerenal AKI and lactic acidosis, which resulted in rapid resolution of his symptoms. Renal function normalised within 12 days of admission. Since diabetic patients commonly use metformin and are also at higher risk of renal dysfunction, this case highlights the vulnerability of this group of patients and the need for increased knowledge and awareness of MALA.

An Analysis of Clinical Outcomes of Exploratory Pediatric Metformin Ingestions Reported to the Texas Poison Center Network From 2011 to 2021

Background: Poison centers develop triage threshold guidelines for pediatric metformin ingestions. Our network uses 1700 mg, or 85 mg/kg. Objective: To describe the dose, clinical course, and outcomes for inadvertent metformin ingestions in children 5 years old and younger reported to our statewide poison center network. Methods: We searched the poison center database 2011 to 2021 for metformin ingestions in patients 5 years and younger. Variables included age, sex, weight, dose, symptoms, outcome, and more. We used descriptive statistics with medians and interquartile ranges (IQR) for continuous variables. Results: Of 669 cases, exposures by age were 208 (31.1%) 1 to 2 years, and 275 (41.1%) 2 years. Weight was recorded in 342 (51.1%) (median 13.5 kg; IQR: 3.7 kg), and dose in 149 (22.3%) (median 500 mg; IQR: 500 mg). Milligram/kilogram values were available for 103 (15.4%) with median 42.4 mg/kg, IQR: 39 mg/kg. Most (647, 98.5%) exposures were unintentional. Most (445/669, 66.5%) were managed at a non-healthcare facility, while 204 (30.7%) were already at or referred to a healthcare facility. Of these 204 patients, 169 (82.8%) were evaluated and treated at the emergency department and discharged. Four (2%) were admitted to critical care, and 7 (3.4%) to the ward. Medical outcomes by effect were 5 (0.7%) minor, 2 (0.3%) moderate, 253 (37.8%) none, 292 (43.6%) not followed (minimal effects possible), and no major effects or deaths. Of 20 clinical occurrences reported, vomiting was most common (8, 1.2%). Conclusion: Despite little recorded dosage information, pediatric metformin ingestions under 85 mg/kg had predominantly uneventful medical outcomes.

Impact of Antidiabetic Drugs on Clinical Outcomes of COVID-19: A Nationwide Population-Based Study

BACKGRUOUND

Inconsistent results have been reported regarding the association between the use of antidiabetic drugs and the clinical outcomes of coronavirus disease 2019 (COVID-19). This study aimed to investigate the effect of antidiabetic drugs on COVID-19 outcomes in patients with diabetes using data from the National Health Insurance Service (NHIS) in South Korea.

METHODS

We analyzed the NHIS data of patients aged ≥20 years who tested positive for COVID-19 and were taking antidiabetic drugs between December 2019 and June 2020. Multiple logistic regression analysis was performed to analyze the clinical outcomes of COVID-19 based on the use of antidiabetic drugs.

RESULTS

A total of 556 patients taking antidiabetic drugs tested positive for COVID-19, including 271 male (48.7%), most of whom were in their sixties. Of all patients, 433 (77.9%) were hospitalized, 119 (21.4%) received oxygen treatment, 87 (15.6%) were admitted to the intensive care unit, 31 (5.6%) required mechanical ventilation, and 61 (11.0%) died. Metformin was significantly associated with the lower risks of mechanical ventilation (odds ratio [OR], 0.281; 95% confidence interval [CI], 0.109 to 0.720; P=0.008), and death (OR, 0.395; 95% CI, 0.182 to 0.854; P=0.018). Dipeptidylpeptidase-4 inhibitor (DPP-4i) were significantly associated with the lower risks of oxygen treatment (OR, 0.565; 95% CI, 0.356 to 0.895; P=0.015) and death (OR, 0.454; 95% CI, 0.217 to 0.949; P=0.036). Sulfonylurea was significantly associated with the higher risk of mechanical ventilation (OR, 2.579; 95% CI, 1.004 to 6.626; P=0.049).

CONCLUSION

In patients with diabetes and COVID-19, metformin exhibited reduced risks of mechanical ventilation and death, DPP- 4i was linked with lower risks of oxygen treatment and death, while sulfonylurea was related to the increased risk of mechanical ventilation.

Causal association of metformin treatment with diverse cardiovascular diseases: a Mendelian randomization analysis

BACKGROUND

The cardiovascular effects of metformin continue to be a subject of debate within the medical community.

METHODS

The Mendelian randomization (MR) study used data from genome-wide association studies (GWAS) to explore the causal association with six diseases that are associated with bimatoprost treatment and myocardial infarction, chronic heart failure, atrial fibrillation, hypertrophic and dilated cardiomyopathy, and valvular disease. Genome-wide significant single nucleotide polymorphisms (SNPs), that are associated with metformin use were selected as the instrumental variables. To determine the causal relationship between metformin use and various cardiovascular diseases, MR analysis was conducted, employing methods such as Instrumental Variable Weighting (IVW).

RESULTS

The IVW analysis demonstrated a positive association between metformin treatment and the risk of myocardial infarction (OR = 22.67, 95% CI 3.22-34.01; P = 0.002). Conversely, metformin treatment exhibited a negative association with the risk of developing valvular disease (OR = 0.98, 95% CI 0.95-1.00; P = 0.046) and hypertrophic cardiomyopathy (OR = 0.01, 95% CI 0.00-0.22; P = 0.016). Multiple test correction found that metformin treatment was causally associated with the risk of both hypertrophic cardiomyopathy (PFDR = 0.048) and myocardial infarction (PFDR = 0.012). The analysis revealed limited heterogeneity in the individual results, absence of pleiotropy evidence, and indications of stability in the findings.

CONCLUSION

The MR study discovered from a genetic standpoint that metformin may lower the risk of hypertrophic cardiomyopathy and valvular heart disease, yet it could elevate the risk of myocardial infarction.

PLGA-based microspheres loaded with metformin hydrochloride: Modified double emulsion method preparation, optimization, characterization, and in vitro evaluation

The modified solvent removal method was used to encapsulate metformin hydrochloride (MH) within poly(lactic-co-glycolic acid) (PLGA) microspheres. The study investigated the effect of varying polymer concentrations on the loading and release of the drug from the microspheres. The encapsulation process involved using a double emulsion method, resulting in microspheres with particle diameters ranging from approximately 4.4μm to 2.7μm. The study achieved high encapsulation efficiencies, ranging from 81% to 90%, with drug loadings ranging from 18% to 11%. The release of the drug from the microspheres followed a biphasic pattern over 24 days, with nearly complete release by the end of the study period. Fourier transform infrared spectroscopy (FTIR) analysis indicated that there were no notable differences between PLGA and MH-loaded microspheres, suggesting minimal interactions between MH and PLGA. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques were used to investigate the state of the MH within the microspheres. The results suggested that the MH was dispersed at a molecular level within the spheres and existed in an amorphous state. This amorphous state of the drug may explain the slow and prolonged release observed in the study.

Metformin Treatment Reduces the Incidence of Rheumatoid Arthritis: A Two-Sample Mendelian Randomized Study

Several studies have shown that rheumatologic patients can benefit from metformin, but it remains unclear whether metformin treatment is causally associated with the risk of rheumatoid arthritis (RA). A two-sample Mendelian randomization (MR) study was conducted to investigate the causal relationship between metformin treatment and the incidence of rheumatoid arthritis. The genome-wide significant (p < 5 × 10^-8) single-nucleotide polymorphisms (SNPs) associated with metformin use were selected as instrumental variables (IVs). Summary statistics on RA were extracted from a large genome-wide association study (GWAS) meta-analysis. The inverse variance-weighted (IVW) method was used as the determinant of the causal effects of metformin treatment on RA. Cochran's Q was used to detect heterogeneity. Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression were used to detect horizontal pleiotropy. A total of 34 SNPs significantly associated with metformin treatment were obtained. Thirty-two SNPs were selected as IVs after removing two SNPs for being palindromic with intermediate allele frequencies (rs11658063 and rs4930011). The IVW results showed a negative causal association between metformin treatment and RA (OR = 0.0232, 95% CI 1.6046 × 10^-3 - 0.3368; p = 0.006). Meanwhile, no heterogeneity or pleiotropy was detected, indicating that the results were reliable. This study indicated a negative causality between metformin treatment and RA, indicating that the treatment of metformin can prevent the pathogenesis of RA.

Metformin-associated lactic acidosis and factors associated with 30-day mortality

Background

Metformin-associated lactic acidosis (MALA) is a rare event but underrecognition may lead to unfavorable outcomes in type 2 diabetes patients. While many risk factors of MALA have been identified, how to reduce mortality from MALA is a matter of debate. This study aimed to explore the factors associated with 30-day mortality amongst MALA patients.

Methods

An observational study enrolled patients diagnosed with MALA between January 2014 and December 2017. MALA was defined by a history of metformin administration, metabolic acidosis (arterial blood gas pH <7.35 or HCO₃ <15 mmol/L), and elevated plasma lactate level (>5 mmol/L). We examined risk factors including age, sex, underlying diseases, current medications, blood tests, disease severity, and dialysis data. Mortality status was identified from medical records or report on telephone.

Results

We included 105 MALA patients. Most patients (95.2%) were diagnosed acute kidney injury stage 3 according to KDIGO 2012 definition. The 30-day mortality rate was 36.2% and dialysis rate was 85.7%. The survivors had higher proportions of underlying chronic kidney disease, presence of metabolic acidosis, receiving renal replacement therapy within 6 hours, and haemodialysis, whereas the non-survivors had higher percentage of hypertension and disease severity. Lower APACHE II score (HR = 0.95; 95%CI, 0.91–0.99; p = 0.038), time to dialysis < 6 hours (0.31; 0.14–0.69; 0.004), and haemodialysis (0.20;0.06–0.67; 0.010) were associated with lower 30-day mortality, using multivariate Cox-regression analysis.

Conclusions

Mortality rate amongst patients with MALA was high. Early dialysis treatment within 6 hours after admission and haemodialysis were independently associated with lower 30-day mortality. The large scale, well-designed studies need to confirm these encouraging results.

Metformin Associated Lactic Acidosis in Clinical Practice - A Case Series

AIMS

The aim of this case report is to specify the frequency and mortality of Metformin-Associated Lactic Acidosis (MALA) in emergency medicine, as the diagnosis seems to occur more often than estimated.

METHODS

To identify the subjects, we developed screening criteria for MALA. We measured the serum metformin concentration to confirm the diagnosis in all patients fulfilling these criteria. Retrospectively the patients were grouped according to individual risk (according to a defined risk score) and the application of renal replacement therapy.

RESULTS

From 2013 until 2018 we were able to identify 11 MALA patients revealing a frequency of 1:4,000 emergency patients. Six patients survived and five died in the follow-up. All three patients in the high-risk group died although all of them received renal replacement therapy. In the low-risk group (three patients, one with renal replacement therapy), all patients survived, while in the intermediate-risk group (five patients, one with renal replacement therapy) three patients survived and two died. Additional severe comorbidities also contributed to mortality.

CONCLUSIONS

Every patient matching the screening criteria of acute renal failure, lactic acidosis and continued intake of metformin can be considered a potential MALA case. A risk score assessment which includes severe comorbidities may help to identify high-risk individuals and should be evaluated in larger studies.To prevent MALA, patients should be trained to immediately interrupt their own metformin use when showing signs of volume depletion. Physicians should be aware of the additional risk factors such as co-medication with diuretics, ACE (angiotensin converting enzyme) ACE inhibitors and NSAIDs (non steroidal anti inflammatory drugs).

The Association between Metformin Therapy and Lactic Acidosis

INTRODUCTION AND OBJECTIVES

There is increasing evidence to suggest that therapeutic doses of metformin are unlikely to cause lactic acidosis. The aims of this research were (1) to formally evaluate the association between metformin therapy and lactic acidosis in published case reports using two causality scoring systems, (2) to determine the frequency of pre-existing independent risk factors in published metformin-associated lactic acidosis cases, (3) to investigate the association between risk factors and mortality in metformin-associated lactic acidosis cases, and (4) to explore the relationship between prescribed metformin doses, elevated metformin plasma concentrations and the development of lactic acidosis in cases with chronic renal impairment.

METHODS

A systematic review was conducted to identify metformin-associated lactic acidosis cases. Causality was assessed using the World Health Organisation-Uppsala Monitoring Centre system and the Naranjo adverse drug reaction probability scale. Compliance to dosing guidelines was investigated for cases with chronic renal impairment as well as the association between steady-state plasma metformin concentrations prior to admission.

RESULTS

We identified 559 metformin-associated lactic acidosis cases. Almost all cases reviewed (97%) presented with independent risk factors for lactic acidosis. The prescribed metformin dose exceeded published guidelines in 60% of cases in patients with impaired kidney function. Metformin steady-state plasma concentrations prior to admission were predicted to be below the proposed upper limit of the therapeutic range of 5 mg/L.

CONCLUSIONS

Almost all cases of metformin-associated lactic acidosis reviewed presented with independent risk factors for lactic acidosis, supporting the suggestion that metformin plays a contributory role. The prescribed metformin dose, on average, exceeded the dosing recommendations by 1000 mg/day in patients with varying degrees of renal impairment but the predicted pre-admission plasma concentrations did not exceed the therapeutic range.

Effect of continuous use of metformin on kidney function in diabetes patients with acute myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

Diabetes patients presenting with ST-segment elevation myocardial infarction (STEMI) scheduled for primary percutaneous coronary intervention (PCI) have an increased risk of contrast induced-acute kidney injury (CI-AKI). The effects of continuous use of metformin on kidney function are still controversial in patients submitted to primary PCI. This study aimed to assess continuous metformin therapy on kidney function in diabetic patients undergoing coronary intervention.

METHODS

Two hundred eighty-four patients with metformin-treated diabetes, who underwent coronary intervention within 24 h for STEMI, were enrolled in the retrospective study. All the patients had estimated glomerular filtration rate (eGFR) of > 30 mL/min/1.73 m2. According to the physicians' decisions after admission, 119 patients continued metformin treatment after primary PCI, while 165 patients discontinued it > 48 h after the procedure. Serum creatinine was collected at admission and within 48 h post primary PCI to evaluate the incidence of CI-AKI. We performed a multiple logistic regression analysis to examine the determinants of CI-AKI.

RESULTS

No statistical difference in CI-AKI incidence between the continuous and the discontinuous metformin group (12.6%vs10.3%, p = 0.545). Multivariable logistic regression analysis indicated eGFR ≤60 ml/min/1.73 m2[p = 0.025, OR: 3.131; 95% CI (1.156-8.482)] and contrast volume [p = 0.002, OR: 1.010; 95% CI (1.004-1.016)] were predictive factors of CI-AKI. Metformin therapy was irrelevant to CI-AKI [p = 0.365, OR: 0.698; 95% CI (0.320-1.521)]. No case of lactic acidosis was found in this study. Besides, the study supported discontinuation of metformin was not beneficial for patients' blood glucose control after admission.

CONCLUSIONS

The study indicated that the metformin continuation after primary PCI for STEMI in diabetic patients with eGFR > 30 ml/min / 1.73 m2 did not increase the risk of CI-AKI.

Metformin: current clinical applications in nondiabetic patients with cancer

Metformin is one of the most commonly used first-line oral medications for type 2 diabetes mellitus. Multiple observational studies, reviewed in numerous systematic reviews, have shown that metformin treatment may not only reduce the risk of cancer but may also improve the efficacy of cancer treatment in diabetic patients. Recent studies have been conducted to determine whether a similar protective effect can be demonstrated in nondiabetic cancer patients. However, the results are controversial. The potential optimal dose, schedule, and duration of metformin treatment and the heterogeneity of histological subtypes and genotypes among cancer patients might contribute to the different clinical benefits. In addition, as the immune property of metformin was investigated, further studies of the immunomodulatory effect of metformin on cancer cells should also be taken into account to optimize its clinical use. In this review, we present and discuss the latest findings regarding the anticancer potential of metformin in nondiabetic patients with cancer.

Risk of Metformin-Associated Lactic Acidosis (MALA) in Patients After Gastric Bypass Surgery

BACKGROUND

Pharmacokinetic data suggest that the risk of metformin-associated lactic acidosis (MALA) may be increased after Roux-en-Y gastric bypass (RYGB) surgery. The aim of this study was to examine the impact of metformin on plasma lactate levels before and after RYGB surgery.

METHODS

Retrospective study of plasma lactate levels before and 3 months after RYGB surgery in patients with type 2 diabetes mellitus (T2DM) not using metformin (MET-0, N = 58), on a stable dose (MET-S, N = 138), or on a decreasing dose (MET-D, N = 85) of metformin.

RESULTS

Preoperatively, lactate levels were similar in patients on metformin (1.8 ± 0.05 mmol/L) and those not on metformin (1.7 ± 0.08 mmol/L), P = 0.21. Three months postoperatively, lactate levels had decreased in all groups (P < 0.001) to 1.3 ± 0.07 (SE), 1.4 ± 0.05, and 1.2 ± 0.05 mmol/l in MET-0, MET-S, and MET-D, respectively. Lactate levels differed between the groups (P = 0.03), with the lowest level in MET-D. The number of patients with hyperlactatemia (lactate > 2 mmol/l) decreased from 31 to 14%, from 22 to 8.6%, and from 26 to 4.7% in MET-S, MET-0, and MET-D, respectively.

CONCLUSION

Mild hyperlactatemia (lactate > 2 mmol/l) is common in morbidly obese patients with T2DM. It is probably related to increase lactate production by adipocytes. Lactate levels decreased after RYGB-induced weight loss, irrespective of the use of metformin. We therefore conclude that there is no need for routinely lowering of the metformin dose after uncomplicated RYGB surgery, as long as normal renal function is preserved.

Hypoglycemia and severe lactic acidosis in a dog following metformin exposure

Hypoglycemia and lactic acidosis are rare complications with metformin use in humans. As metformin is not commonly used in veterinary medicine, severe adverse effects secondary to exposure are not known. Awareness of potentially life-threatening complications with metformin exposure is an important addition to the veterinary literature.

Towards natural mimetics of metformin and rapamycin

Aging is now at the forefront of major challenges faced globally, creating an immediate need for safe, widescale interventions to reduce the burden of chronic disease and extend human healthspan. Metformin and rapamycin are two FDA-approved mTOR inhibitors proposed for this purpose, exhibiting significant anti-cancer and anti-aging properties beyond their current clinical applications. However, each faces issues with approval for off-label, prophylactic use due to adverse effects. Here, we initiate an effort to identify nutraceuticals-safer, naturally-occurring compounds-that mimic the anti-aging effects of metformin and rapamycin without adverse effects. We applied several bioinformatic approaches and deep learning methods to the Library of Integrated Network-based Cellular Signatures (LINCS) dataset to map the gene- and pathway-level signatures of metformin and rapamycin and screen for matches among over 800 natural compounds. We then predicted the safety of each compound with an ensemble of deep neural network classifiers. The analysis revealed many novel candidate metformin and rapamycin mimetics, including allantoin and ginsenoside (metformin), epigallocatechin gallate and isoliquiritigenin (rapamycin), and withaferin A (both). Four relatively unexplored compounds also scored well with rapamycin. This work revealed promising candidates for future experimental validation while demonstrating the applications of powerful screening methods for this and similar endeavors.

Association between Metformin Use and Risk of Lactic Acidosis or Elevated Lactate Concentration in Type 2 Diabetes

PURPOSE

Metformin can reduce diabetes-related complications and mortality. However, its use is limited because of potential lactic acidosis-associated adverse effects, particularly in renal impairment patients. We aimed to investigate the association of metformin use with lactic acidosis and hyperlactatemia in patients with type 2 diabetes.

MATERIALS AND METHODS

This was a cross-sectional study from a tertiary university-affiliated medical center. A total of 1954 type 2 diabetes patients were recruited in 2007-2011, and stratified according to the estimated glomerular filtration rate of 60 mL/min/1.73 m². Lactic acidosis was defined as plasma lactate levels >5 mmol/L and arterial pH <7.35.

RESULTS

Metformin was used in 61.4% of the patients with type 2 diabetes mellitus. Plasma lactate levels were not different in the patients with and without metformin use. There was no difference in prevalence of hyperlactatemia and lactic acidosis between the patients with and without metformin use (18.9% vs. 18.7%, p=0.905 for hyperlactatemia and 2.8% vs. 3.3%, p=0.544 for lactic acidosis). Similar results were observed in the patients with estimated glomerular filtration rate <60 mL/min/1.73 m². Most patients with lactic acidosis had at least one condition related to hypoxia or poor tissue perfusion. Multiple regression analysis indicated no association between metformin use and lactic acidosis, whereas tissue hypoxia was an independent risk factor for lactic acidosis [odds ratio 4.603 (95% confidence interval, 1.327-15.965)].

CONCLUSION

Metformin use was not associated with hyperlactatemia or lactic acidosis in patients with type 2 diabetes.

Metformin-Associated Lactic Acidosis: An Atypical Presentation

Many Type 2 diabetic patients take metformin for its safety profile and lack of hypoglycemia. Although this drug is safe in those without renal dysfunction, lactic acidosis may rarely occur. Metformin-associated lactic acidosis is a potentially fatal yet rare diagnosis. Prompt recognition of even subtle symptoms can reduce mortality and preserve homeostasis.

Lactic acidosis and the relationship with metformin usage: Case reports

AIMS

The principal objective of this study was to retrospectively review a series of cases of lactic acidosis (LA) in patients with type 2 diabetes mellitus (T2DM) and examine the relationship with the use of metformin. More generally, the study enabled an investigation of the profiles of patients diagnosed with LA and clinical variables associated with in-hospital mortality.

METHODS

All patients admitted to the Royal Hobart Hospital in Tasmania with LA (lactate >5.0 mmol/L and pH <7.35) over a 4-year period were included. Data extracted included patient demographics, medical history, medications, acute and chronic conditions associated with LA, and relevant pathology results. Multivariate logistic regression analysis was used to identify predictors for in-hospital mortality in patients with LA.

RESULTS

A total of 139 patients with LA were included in this study. Of these, 23 patients had T2DM and 11 patients were taking metformin. All metformin-treated patients had at least 1 additional medical condition (either chronic or acute) associated with an increased risk for LA. More than half (n = 72, 51.8%) of the patients with LA died during hospitalization. Multivariate logistic regression revealed older age and lower pH as the significant independent predictors (P < 0.05) for in-hospital mortality.

CONCLUSION

LA was associated with high in-hospital mortality, with older age and lower pH as the significant risk factors for mortality. In patients with LA, approximately half of the patients with T2DM were receiving metformin. All the patients treated with metformin had other medical conditions that were risk factors for developing LA. The role of LA in patients treated with metformin is seemingly overemphasized.

Risk assessment and management of post-transplant diabetes mellitus

The success rate of organ transplantation has been increasing with advances in surgical and pharmacological techniques. However, the number of solid organ transplant recipients who require metabolic disease management is also growing. Post-transplant diabetes mellitus (PTDM) is a common complication after solid organ transplantation and is associated with risks of graft loss, cardiovascular morbidity, and mortality. Other risk factors for PTDM include older age, genetic background, obesity, hepatitis C virus infection, hypomagnesemia, and use of immunosuppressant agents (corticosteroids, calcineurin inhibitors, and mammalian target of rapamycin inhibitor). Management of PTDM should be started before the transplantation plan to properly screen high-risk patients. Even though PTDM management is similar to that of general type 2 diabetes, therapeutic approaches must be made with consideration of drug interactions between immunosuppressive agents, glucose-lowering medications, and graft rejection and function.

Temporal trends in the use of antidiabetic medicines: a nationwide 9-year study in older people living in New Zealand

BACKGROUND

The global burden of diabetes is increasing worldwide. The aim of the study was to investigate the trends in use of antidiabetic medicines among older New Zealanders between 2005 and 2013, and to perform a separate analysis by age, sex, ethnicity, district health board domicile and socioeconomic deprivation index.

METHODS

The study population included individuals' aged 65 years and older living in New Zealand (NZ) captured in the pharmaceutical collections. Repeated cross-sectional analysis of population-level dispensing data was conducted from 1 January 2005 to 31 December 2013. Linear regression model using a gamma link function was used to estimate prevalence ratios and trends between 2005 and 2013. The main outcome measure was the prevalence of antidiabetic medicines in older New Zealanders.

RESULTS

The prevalence of antidiabetic medicines in older New Zealanders increased by 17.6% between 2005 and 2013. Individuals in the 70-74 age group had the highest utilization of each of the classes of antidiabetic medicines and those aged ⩾85 had the lowest utilization. Among the antidiabetic class of medicines, utilization of sulfonylureas was highest and alpha-glucosidase inhibitors the least. The utilization of thiazolidinediones increased over the study period. In 2013, insulin isophane and insulin glargine were the most common insulin analogues used. Insulin use was high in those aged ⩾85 years across the entire study period. The utilization of metformin increased gradually throughout the study period (by 43.9% in 2013 compared with 2005).

CONCLUSION

This population-level study showed an increase in utilization of antidiabetic medicines in older people in NZ from 2005 to 2013; however, the increase does not seem to parallel the proportional increase in prevalence of diabetes for the study period. Improving access to newer antidiabetic medicines in line with emerging evidence should be a consideration for decision makers.

Metformin stimulates IGFBP-2 gene expression through PPARalpha in diabetic states

The anti-diabetic drug, metformin, exerts its action through AMP-activated protein kinase (AMPK), and Sirtuin (Sirt1) signaling. Insulin-like growth factor (IGF)-binding protein 2 (IGFBP-2) prevents IGF-1 binding to its receptors, thereby contributing to modulate insulin sensitivity. In this study, we demonstrate that metformin upregulates Igfbp-2 expression through the AMPK-Sirt1-PPARα cascade pathway. In the liver of high fat diet, ob/ob, and db/db mice, Igfbp-2 expression was significantly decreased compared to the expression levels in the wild-type mice (p < 0.05). Upregulation of Igfbp-2 expression by metformin administration was disrupted by gene silencing of Ampk and Sirt1, and this phenomenon was not observed in Pparα-null mice. Notably, activation of IGF-1 receptor (IGF-1R)-dependent signaling by IGF-1 was inhibited by metformin. Finally, when compared to untreated type 2 diabetes patients, the metformin-treated diabetic patients showed increased IGFBP-2 levels with diminished serum IGF-1 levels. Taken together, these findings indicate that IGFBP-2 might be a new target of metformin action in diabetes and the metformin-AMPK-Sirt1-PPARα-IGFBP-2 network may provide a novel pathway that could be applied to ameliorate metabolic syndromes by controlling IGF-1 bioavailability.

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 (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.

Diabetes mellitus in elderly

Diabetes mellitus (DM) frequency is a growing problem worldwide, because of long life expectancy and life style modifications. In old age (≥60-65 years old), DM is becoming an alarming public health problem in developed and even in developing countries as for some authors one from two old persons are diabetic or prediabetic and for others 8 from 10 old persons have some dysglycemia. DM complications and co-morbidities are more frequent in old diabetics compared to their young counterparts. The most frequent are cardiovascular diseases due to old age and to precocious atherosclerosis specific to DM and the most bothersome are visual and cognitive impairments, especially Alzheimer disease and other kind of dementia. Alzheimer disease seems to share the same risk factors as DM, which means insulin resistance due to lack of physical activity and eating disorders. Visual and physical handicaps, depression, and memory troubles are a barrier to care for DM treatment. For this, old diabetics are now classified into two main categories as fit and independent old people able to take any available medication, exactly as their young or middle age counterparts, and fragile or frail persons for whom physical activity, healthy diet, and medical treatment should be individualized according to the presence or lack of cognitive impairment and other co-morbidities. In the last category, the fundamental rule is "go slowly and individualize" to avoid interaction with poly medicated elder persons and fatal iatrogenic hypoglycemias in those treated with sulfonylureas or insulin.

Metformin: risk-benefit profile with a focus on cancer

INTRODUCTION

Epidemiological evidence suggests an increased incidence of cancer in obese, prediabetic, and diabetic patients and a reduced risk of cancer incidence and mortality in diabetic patients on metformin compared with other antidiabetic drugs. In vitro studies support the efficacy of metformin in cancer therapy and prevention. Although metformin seems to be promising as a cancer chemopreventive or therapeutic drug, the principal consideration is whether metformin will be effective in cancer clinical trials for nondiabetic subjects or only in diabetics or subjects with insulin resistance. Safety of metformin is even more important in treating nondiabetic patients.

AREAS COVERED

The present review focuses on epidemiological data and clinical trials testing the efficacy of metformin on cancer, the safety in nondiabetic patients and the future development of this promising drug.

EXPERT OPINION

Meta-analyses of epidemiological in which metformin treatment has been used for diabetic patients show a positive trend for benefit; nevertheless, clinical data outcomes are preliminary and the results of ongoing trials are awaited. The different types of cancer, heterogeneity of populations and presence of comorbidity make it difficult to determine the benefits of metformin in cancer prevention and treatment.