Use of Metformin in Patients with Kidney and Cardiovascular Diseases

Anti-Inflammatory Potential of the Anti-Diabetic Drug Metformin in the Prevention of Inflammatory Complications and Infectious Diseases Including COVID-19: A Narrative Review

Metformin, a widely used first-line anti-diabetic therapy for the treatment of type-2 diabetes, has been shown to lower hyperglycemia levels in the blood by enhancing insulin actions. For several decades this drug has been used globally to successfully control hyperglycemia. Lactic acidosis has been shown to be a major adverse effect of metformin in some type-2 diabetic patients, but several studies suggest that it is a typically well-tolerated and safe drug in most patients. Further, recent studies also indicate its potential to reduce the symptoms associated with various inflammatory complications and infectious diseases including coronavirus disease 2019 (COVID-19). These studies suggest that besides diabetes, metformin could be used as an adjuvant drug to control inflammatory and infectious diseases. In this article, we discuss the current understanding of the role of the anti-diabetic drug metformin in the prevention of various inflammatory complications and infectious diseases in both diabetics and non-diabetics.

Peter WL. Glucose-Lowering Medication Use in CKD: Analysis of US Medicare Beneficiaries Between 2007 and 2016

BACKGROUND

Information regarding the use of glucose-lowering medications in patients with chronic kidney disease (CKD) is limited.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Medicare 5% random sample of patients with CKD with type 2 diabetes, 2007 to 2016.

PREDICTORS

Study year, CKD stage, low-income subsidy status, and demographic characteristics (age, sex, and race/ethnicity).

OUTCOMES

Trends in use of glucose-lowering medications.

ANALYTICAL APPROACH

Yearly cohorts of patients with CKD and type 2 diabetes were created. Descriptive statistics were used to report proportions of patients using glucose-lowering medications. To test overall trends in glucose-lowering medication classes, linear probability models with adjustment for age, sex, race/ethnicity, CKD stage, and low-income subsidy status were used.

RESULTS

Metformin use increased significantly from 32.7% in 2007 to 48.7% in 2016. Use of newer classes of glucose-lowering medications increased significantly, including dipeptidyl peptidase 4 inhibitors (5.6%, 2007; 21.7%, 2016), glucagon-like peptide 1 receptor agonists (2.3%, 2007; 6.1%, 2016), and sodium-glucose cotransporter 2 inhibitors (0.2%, 2013; 3.3%, 2016). Newer insulin analogue use increased from 37.2% in 2007 to 46.3% in 2013 and then remained steady. Use of sulfonylureas, thiazolidinediones, older insulins (human regular and neutral protamine Hagedorn), α-glucosidase inhibitors, amylin mimetics, and meglitinides decreased significantly. Insulin was the most highly used single medication class. Insulin use was higher among low-income subsidy than among non-low-income subsidy patients. Combination therapy was less common as CKD stage increased.

LIMITATIONS

Patients with CKD and type 2 diabetes and the CKD stages were identified with diagnosis codes and could not be verified through medical record review. Our results may not be generalizable to younger patients with CKD with type 2 diabetes.

CONCLUSIONS

Use of metformin and newer glucose-lowering medication classes is increasing in patients with CKD with type 2 diabetes. We anticipate that percentages of patients with CKD using these newer agents will increase.

Metformin-associated Lactic Acidosis: An Unexpected Scenario

According to the National Diabetes Statistics Report (2017) by Centers for Disease Control and Prevention (CDC), 9.4% of the US population, approximately 30.3 million people had diabetes while 84.1 million had pre-diabetes as of 2015. In addition to lifestyle changes, the American Diabetes Association recommends metformin as the first-line treatment for type 2 diabetes. Hence, not surprisingly, metformin is a commonly prescribed medication by most healthcare providers in all clinical settings. As a result, it remains essential that all medical professionals be aware of any adverse effects as a result of metformin therapy, no matter how uncommon. We present the case of a 42-year-old lady with type 2 diabetes mellitus who required initial admission to intensive care unit (ICU) after presenting with unilateral back and lower abdominal pain with dysuria and was noted to have an acute kidney injury with a creatinine of 7.45 mg/dL and severe metabolic acidosis with a pH of 6.7 and an anion gap more than 50 mmol/L. Lactic acid was elevated at 24.2 mmol/L. Serum metformin levels were high at 14 mcg/mL (therapeutic range: 1-2 mcg/mL). She required emergent dialysis but subsequently, renal functions recovered. Risk of metformin-associated lactic acidosis (MALA) is reported to be an estimated 6.3 per 100,000 patient-years. Commonly encountered clinical scenarios such as hypoxemia, sepsis, alcohol abuse, renal injury, and shock can precipitate MALA. Early recognition allows timely initiation of appropriate therapy and reduces associated morbidity.

Prenatal Metformin Therapy Attenuates Hypertension of Developmental Origin in Male Adult Offspring Exposed to Maternal High-Fructose and Post-Weaning High-Fat Diets

Widespread consumption of a Western diet, comprised of highly refined carbohydrates and fat, may play a role in the epidemic of hypertension. Hypertension can take origin from early life. Metformin is the preferred treatment for type 2 diabetes. We examined whether prenatal metformin therapy can prevent maternal high-fructose plus post-weaning high-fat diets-induced hypertension of developmental origins via regulation of nutrient sensing signals, uric acid, oxidative stress, and the nitric oxide (NO) pathway. Gestating Sprague–Dawley rats received regular chow (ND) or chow supplemented with 60% fructose diet (HFR) throughout pregnancy and lactation. Male offspring were onto either the ND or high-fat diet (HFA) from weaning to 12 weeks of age. A total of 40 male offspring were assigned to five groups (n = 8/group): ND/ND, HFR/ND, ND/HFA, HFR/HFA, and HFR/HFA+metformin. Metformin (500 mg/kg/day) was administered via gastric gavage for three weeks during the pregnancy period. Combined maternal HFR plus post-weaning HFA induced hypertension in male adult offspring, which prenatal metformin therapy prevented. The protective effects of prenatal metformin therapy on HFR/HFA-induced hypertension, including downregulation of the renin-angiotensin system, decrease in uric acid level, and reduction of oxidative stress. Our results highlighted that the programming effects of metformin administered prenatally might be different from those reported in adults, and that deserves further elucidation.

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.

Heart healthy equals prostate healthy and statins, aspirin, and/or metformin (S.A.M.) are the ideal recommendations for prostate cancer prevention

Cardiovascular disease (CVD) has been the number one cause of death in the U.S. for 114 of the last 115 years. Lifestyle factors that promote CVD also appear to increase prostate cancer risk and those that reduce CVD risk also appear to reduce the risk of prostate cancer. The largest randomized trials utilizing dietary supplements or pharmacologic agents for prostate cancer prevention (Selenium and Vitamin E Cancer Prevention Trial [SELECT]) have also shed light on the problems and future solutions in this area. Dietary supplements that have not been found to be CVD protective, such as selenium and Vitamin E have not been found to be prostate protective. In addition, over exposure to specific anti-oxidants in nutritionally replete populations may be encouraging cancer growth. Future trials of dietary supplements to prevent prostate cancer could be problematic because by the time a definitive trial is initiated the participants will no longer be “deficient” in the nutrient being tested, which arguably occurred in the SELECT trial. It is also interesting that statins, aspirin, and/or metformin (S.A.M.) are 3 generic, low-cost, heart healthy agents derived from natural sources with separate mechanism of actions, which all appear to have the best benefit to risk ratio compared to any other agent available for prostate cancer prevention, especially aggressive disease, or as an ancillary agent (s) to conventional cancer treatment. It is time to focus on the forest over the trees and recommend proven CVD protective measures for men concerned about their risk of prostate cancer.

Metformin ameliorates ionizing irradiation-induced long-term hematopoietic stem cell injury in mice

Exposure to ionizing radiation (IR) increases the production of reactive oxygen species (ROS) not only by the radiolysis of water but also through IR-induced perturbation of the cellular metabolism and disturbance of the balance of reduction/oxidation reactions. Our recent studies showed that the increased production of intracellular ROS induced by IR contributes to IR-induced late effects, particularly in the hematopoietic system, because inhibition of ROS production with an antioxidant after IR exposure can mitigate IR-induced long-term bone marrow (BM) injury. Metformin is a widely used drug for the treatment of type 2 diabetes. Metformin also has the ability to regulate cellular metabolism and ROS production by activating AMP-activated protein kinase. Therefore, we examined whether metformin can ameliorate IR-induced long-term BM injury in a total-body irradiation (TBI) mouse model. Our results showed that the administration of metformin significantly attenuated TBI-induced increases in ROS production and DNA damage and upregulation of NADPH oxidase 4 expression in BM hematopoietic stem cells (HSCs). These changes were associated with a significant increase in BM HSC frequency, a considerable improvement in in vitro and in vivo HSC function, and complete inhibition of upregulation of p16(Ink4a) in HSCs after TBI. These findings demonstrate that metformin can attenuate TBI-induced long-term BM injury at least in part by inhibiting the induction of chronic oxidative stress in HSCs and HSC senescence. Therefore, metformin has the potential to be used as a novel radioprotectant to ameliorate TBI-induced long-term BM injury.

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).

Evaluating the potential benefits of metformin in patients with cardiovascular disease and heart failure

OBJECTIVE

To examine the safety and potential benefits of metformin in diabetic patients with cardiovascular (CV) disease and heart failure (HF).

DATA SOURCES

Searches of MEDLINE and International Pharmaceutical Abstracts (1966-August 2012). Search terms included metformin, lactic acidosis, cardiovascular disease, diabetes, heart failure, and clinical trials.

STUDY SELECTION AND DATA EXTRACTION

Published studies and case reports that were chosen for inclusion evaluated the benefit and safety of metformin in patients with diabetes with CV disease and HF.

DATA SYNTHESIS

Case reports and retrospective trials have failed to illustrate an association with metformin use and lactic acidosis in patients with HF or cardiac disease. In fact, the evidence has suggested that these patients may actually benefit from the use of metformin.

CONCLUSIONS

Results from recent trials have evaluated the potential clinical advantages of metformin in patients with cardiac disease and HF. These studies have illustrated a favorable morbidity and mortality profile for the use of metformin in these patient populations. While large prospective trials are still needed to display conclusive evidence, the recent clinical trials suggest a benefit in areas where metformin use has previously been discouraged.

Cardiovascular disease in diabetes mellitus: risk factors and medical therapy

Cardiovascular disease is a serious complication of diabetes mellitus. In the last 2 decades, great strides have been made in reducing microvascular complications in patients with diabetes through improving glycemic control. Decreasing rates of cardiovascular events have proved to be more difficult than simply intensifying the management of hyperglycemia. A tremendous effort has been made to deepen understanding of cardiovascular disease in diabetes and to formulate the best treatment approach. This review summarizes the current state of knowledge and discusses areas of uncertainty in the care of patients with diabetes who are at risk for cardiovascular disease.

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

OBJECTIVE

We compared and contrasted guidelines on metformin treatment in patients with chronic kidney disease (CKD) around the world, with the aim of helping physicians to refine their analysis of the available evidence before deciding whether to continue or withdraw this drug.

METHODS

We performed a systematic research for metformin contraindications in: (i) official documents from the world's 20 most populated countries and the 20 most scientifically productive countries in the field of diabetology and (ii) publications referenced in electronic databases from 1990 onwards.

RESULTS

We identified three international guidelines, 31 national guidelines, and 20 proposals in the scientific literature. The criteria for metformin withdrawal were (i) mainly qualitative in the most populated countries; (ii) mainly quantitative in the most scientifically productive countries (with, in all cases, a suggested threshold for withdrawing metformin); and (iii) quantitative in all, but one of the literature proposals, with a threshold for withdrawal in most cases (n = 17) and/or adjustment of the metformin dose as a function of renal status (n = 8). There was a good degree of consensus on serum creatinine thresholds; whereas guidelines based on estimated glomerular filtration rate thresholds varied from 60 mL/minute/1.73 m(2) up to stage 5 CKD. Only one of the proposals has been tested in a prospective study.

CONCLUSIONS

In general, proposals for continuing or stopping metformin therapy in CKD involve a threshold (whether based on serum creatinine or estimated glomerular filtration rate) rather than the dose adjustment as a function of renal status (in stable patients) performed for other drugs excreted by the kidney.

Metformin revisited: a critical review of the benefit-risk balance in at-risk patients with type 2 diabetes

Metformin is unanimously considered a first-line glucose-lowering agent. Theoretically, however, it cannot be prescribed in a large proportion of patients with type 2 diabetes because of numerous contraindications that could lead to an increased risk of lactic acidosis. Various observational data from real-life have shown that many diabetic patients considered to be at risk still receive metformin and often without appropriate dose adjustment, yet apparently with no harm done and particularly no increased risk of lactic acidosis. More interestingly, recent data have suggested that type 2 diabetes patients considered at risk because of the presence of traditional contraindications may still derive benefit from metformin therapy with reductions in morbidity and mortality compared with other glucose-lowering agents, especially sulphonylureas. The present review analyzes the benefit-risk balance of metformin therapy in special populations, namely, patients with stable coronary artery disease, acute coronary syndrome or myocardial infarction, congestive heart failure, renal impairment or chronic kidney disease, hepatic dysfunction and chronic respiratory insufficiency, all conditions that could in theory increase the risk of lactic acidosis. Special attention is also paid to elderly patients with type 2 diabetes, a population that is growing rapidly, as older patients can accumulate several comorbidities classically considered contraindications to the use of metformin. A review of the recent scientific literature suggests that reassessment of the contraindications of metformin is now urgently needed to prevent physicians from prescribing the most popular glucose-lowering therapy in everyday clinical practice outside of the official recommendations.

Metformin: the hidden chronicles of a magic drug

Metformin, a biguanide is well known treatment for type 2 diabetes mellitus that has diverse mechanism of actions. Various studies have elucidated the role of this drug in different pathologies. The well-known United Kingdom Prospective Diabetic Study (UKPDS) has observed its survival benefits in a large cohort of individuals. Data has been conclusive that metformin also has beneficial role in lipid disorders as it improves the markers of metabolic syndrome. Studies have also shown the beneficial roles in antipsychotic induced weight gain as well as HIV lipodystrophy syndrome. Evidence is accumulating that metformin also improves the fertility in females with Polycystic Ovarian Syndrome (PCOS). It also delays aging and is effective in aging related disorders and is equally effective in inflammation related disorders at least in different rodent studies. Metformin's major effect has been shown in various cancers ranging from solid to hematological malignancies. Researchers are working to reveal more benefits of this magic drug but it remains an unexplored territory for the medical community.

Activation of AMPK by the putative dietary restriction mimetic metformin is insufficient to extend lifespan in Drosophila

The biguanide drug, metformin, commonly used to treat type-2 diabetes, has been shown to extend lifespan and reduce fecundity in C. elegans through a dietary restriction-like mechanism via the AMP-activated protein kinase (AMPK) and the AMPK-activating kinase, LKB1. We have investigated whether the longevity-promoting effects of metformin are evolutionarily conserved using the fruit fly, Drosophila melanogaster. We show here that while feeding metformin to adult Drosophila resulted in a robust activation of AMPK and reduced lipid stores, it did not increase lifespan in either male or female flies. In fact, we found that when administered at high concentrations, metformin is toxic to flies. Furthermore, no decreases in female fecundity were observed except at the most toxic dose. Analysis of intestinal physiology after metformin treatment suggests that these deleterious effects may result from disruptions to intestinal fluid homeostasis. Thus, metformin appears to have evolutionarily conserved effects on metabolism but not on fecundity or lifespan.

Proposal for the administration of metformin in patients with chronic kidney disease

Metformin is the first-line, widely used oral antidiabetic agent for the management of type 2 diabetes. There is increasing evidence that metformin use results in a reduction in cardiovascular morbidity and mortality, and might have anticancer activity. An extremely rare, but potentially life-threatening adverse effect of metformin is lactic acidosis, therefore, its use is traditionally contraindicated if the glomerular filtrate rate is below 60 mL/min. However, lactic acidosis is always associated with acute events, such as hypovolemia, acute cardiorespiratory illness, severe sepsis and acute renal or hepatic failure. Furthermore, administration of insulins and conventional antihyperglycemic agents increases the risk of severe hypoglycemic events when renal function is reduced. Therefore, the magnitude of the benefit of metformin use would outweigh potential risk of lactic acidosis in moderate chronic renal disease. After reviewing the literature, the authors give a proposal for the administration of metformin, according to the calculated glomerular filtrate rate. Orv.Hetil., 2012, 153, 1527–1535.

Managing Diabetes in Patients With Diabetes of Long Duration

Purpose

The purpose of this article is to review clinical issues related to the management of hyperglycemia in older patients with diabetes of long duration.

Conclusion

Older adults represent an extensive proportion of patients with type 2 diabetes. Treatment goals need to be individualized to take into account comorbid conditions, life expectancy, diabetes complications, and the benefits of glycemic control. For both older patients and especially those with chronic renal insufficiency, the most important drug-related adverse effect to avoid is hypoglycemia, and avoidance of any severe hypoglycemia should be paramount. Patients with long duration of diabetes are often treated with insulin. Recent data show that glucagon-like peptide-1 receptor agonists may be used in combination with insulin for patients not achieving glycemic goals, with reductions in the doses of insulin used and with a low risk of hypoglycemia and possible weight loss.