Diabetes medication use and blood lactate level among participants with type 2 diabetes: the atherosclerosis risk in communities carotid MRI study

Impact of COVID-19 on metabolic parameters in patients with type 2 diabetes mellitus

BACKGROUND AND AIM

The Coronavirus Disease 2019 (COVID-19) pandemic has disproportionately affected individuals with Type 2 Diabetes Mellitus (T2DM), making them more susceptible to viral infections. Additionally, COVID-19 and the associated lockdown restrictions have influenced metabolic regulatory mechanisms in this population. This study aims to evaluate the impact of COVID-19 infection and lockdown measures on physiological parameters in individuals with T2DM.

METHODS

This retrospective cohort study included 118 individuals with a prior diagnosis of T2DM. Medical records were reviewed for laboratory tests conducted within three months before the onset of the COVID-19 pandemic in Iran. Fifty-nine patients with confirmed COVID-19 infection during the first three months of the pandemic underwent follow-up laboratory tests six months post-diagnosis. An age- and gender-matched group of 59 noninfected individuals underwent follow-up tests six months after the pandemic's onset. Clinical and laboratory parameters were analyzed and compared within each group.

RESULTS

In the COVID-19 positive group, significant reductions were observed in triglycerides (TG) (P = 0.001), total cholesterol (TC) (P = 0.028), body mass index (BMI) (P = 0.034), atherogenic index of plasma (AIP) (P = 0.027), triglyceride-glucose (TyG) index (P = 0.001), and triglyceride-glucose-BMI (TyG-BMI) index (P < 0.001) during the six months following infection compared to pre-pandemic levels. Other variables remained unchanged. In the COVID-19 negative group, significant reductions were noted in TC (P = 0.001) and low-density lipoprotein cholesterol (LDL-C) (P = 0.01).

CONCLUSION

T2DM patients with mild to moderate COVID-19 infection exhibited improvements in TC, TG, BMI, and insulin-related indices. Lockdown restrictions were associated with decreased TC and LDL-C levels in T2DM patients without a history of COVID-19 infection.

The impact of high altitude (hypobaric hypoxia) on insulin resistance in humans

Exposure to hypobaric hypoxia (high altitude) diminishes systemic tissue oxygenation. Tissue hypoxia induces insulin resistance and a metabolic switch that reduces oxidative phosphorylation and glucose storage while enhancing glycolysis. Similarly to hypobaric hypoxia, insulin resistance develops in normal humans undergoing normobaric hypoxia and in patients with obstructive sleep apnea. Following acute exposure to high altitude, insulin resistance returns to baseline values upon returning to sea level or when compensatory mechanisms restore tissue oxygenation. However, insulin resistance persists in subjects unable to achieve sufficient oxygen delivery to tissues. Likewise, long-term residents at high altitude develop persistent insulin resistance when compensatory mechanisms do not attain adequate tissue oxygenation. Among these subjects, insulin resistance may cause clinical complications, such as hypertriglyceridemia, reduced HDL-c, visceral obesity, metabolic dysfunction-associated steatotic liver disease, essential hypertension, type 2 diabetes, subclinical vascular injury, cardiovascular disease, and kidney disease. Impaired tissue oxygenation allows the stabilization of hypoxia-inducible factor-1 (HIF-1), a transcription factor that modulates the transcriptional activity of a number of genes to coordinate the physiological responses to tissue hypoxia. Among them, HIF-1 downregulates PPARG, that codes peroxisome proliferator-activated receptor-gamma (PPAR-γ) and PPARGCA, that codes PPAR-γ coactivator-1α, in order to enable insulin resistance and the metabolic switch from oxidative phosphorylation toward glycolysis.

Does the Same Hyperlactatemia Cut-Off in the Context of Acute Diseases Hold the Same Meaning in Diabetes Mellitus?

Background

Hyperlactatemia is defined by a lactate concentration of >2 mmol/L, and a lactate concentration of above >4 mmol/L is commonly used to define severe hyperlactatemia. It is a common disorder in critically ill patients and is associated with adverse prognosis. Diabetes mellitus(DM) can also be associated with increased lactate levels at baseline. In this study, we aimed to document the development of severe hyperlactatemia in acute situations among patients with and without DM, to analyze potential contributors to lactate elevation and their impact on mortality, and to analyze whether lactate concentrations of >4 mmol/L have equal prognostic significance in patients with and without DM.

Methodology

A retrospective, cross-sectional study was performed among patients admitted to our internal medicine wards in the context of acute disease with lactate concentrations of ​​≥2 mmol/L. Data were collected regarding age, sex, highest lactate concentrations, cause of hyperlactatemia, DM, and mortality. Statistical analysis was performed using SPSS version 23.

Results

In total, 151 patients with lactate levels of ≥2 mmol/L were analyzed. The mean age of the patients was 78.2 ± 14.9 years, and 55% of the patients were female. Overall, 55.6% of the patients had DM, as well as higher lactatemia of 6.3 ± 3.4 mmol/L (vs 5.1 ± 3.2 in non-DM patients, p = 0.003), with the majority reaching values of >4 mmol/L (vs 34.8% in non-DM patients). When potential contributors to the development of severe hyperlactatemia (lactate >4 mmol/L) were analyzed in DM patients, metformin consumption concomitantly with factors potentiating its accumulation, sepsis/septic shock, ischemia, and neoplasia were the most frequently identified contributors. In non-DM patients, the three former factors were also the most frequently reported. The 30-day mortality rate was 25.82%, with deceased patients also displaying a higher lactatemia of 6.5 ± 3.2 mmol/L (vs. 5.5 ± 3.3 mmol/L in patients who survived) (p = 0.037). In multivariate analysis, lactate values of >4 mmol/L were an independent predictor of mortality in the entire sample and in the subgroup without DM, but not in DM patients.

Conclusions

In our sample, patients with DM had higher lactate levels than non-DM patients. Our analysis raises the possibility that the same lactate values may not have equal capacity to assess prognosis in acute situations in patients with and without DM. Large-scale studies are needed to optimize cut-off points for lactatemia in patients with high baseline values, such as DM patients.

Blood glucose regulation in context of infection

The immune and endocrine systems collectively control homeostasis in the body. The endocrine system ensures that values of essential factors and nutrients such as glucose, electrolytes and vitamins are maintained within threshold values. The immune system resolves local disruptions in tissue homeostasis, caused by pathogens or malfunctioning cells. The immediate goals of these two systems do not always align. The immune system benefits from optimal access to nutrients for itself and restriction of nutrient availability to all other organs to limit pathogen replication. The endocrine system aims to ensure optimal nutrient access for all organs, limited only by the nutrients stores that the body has available. The actual state of homeostatic parameters such as blood glucose levels represents a careful balance based on regulatory signals from the immune and endocrine systems. This state is not static but continuously adjusted in response to changes in the current metabolic needs of the body, the amount of resources it has available and the level of threats it encounters. This balance is maintained by the ability of the immune and endocrine systems to interact and co-regulate systemic metabolism. In context of metabolic disease, this system is disrupted, which impairs functionality of both systems. The failure of the endocrine system to retain levels of nutrients such as glucose within threshold values impairs functionality of the immune system. In addition, metabolic stress of organs in context of obesity is perceived by the immune system as a disruption in local homeostasis, which it tries to resolve by the excretion of factors which further disrupt normal metabolic control. In this chapter, we will discuss how the immune and endocrine systems interact under homeostatic conditions and during infection with a focus on blood glucose regulation. In addition, we will discuss how this system fails in the context of metabolic disease.

Type 2 diabetes and viral infection; cause and effect of disease

The recent pandemic of COVID-19 has made abundantly clear that Type 2 diabetes (T2D) increases the risk of more frequent and more severe viral infections. At the same time, pro-inflammatory cytokines of an anti-viral Type-I profile promote insulin resistance and form a risk factor for development of T2D. What this illustrates is that there is a reciprocal, detrimental interaction between the immune and endocrine system in the context of T2D. Why these two systems would interact at all long remained unclear. Recent findings indicate that transient changes in systemic metabolism are induced by the immune system as a strategy against viral infection. In people with T2D, this system fails, thereby negatively impacting the antiviral immune response. In addition, immune-mediated changes in systemic metabolism upon infection may aggravate glycemic control in T2D. In this review, we will discuss recent literature that sheds more light on how T2D impairs immune responses to viral infection and how virus-induced activation of the immune system increases risk of development of T2D.

Interactions among endotoxin, uric acid, and lactate in relation to the risk of type 2 diabetes: A population-based study

BACKGROUND

Blood levels of endotoxin, uric acid (UA), or lactate (LAC) are associated with type 2 diabetes mellitus (T2DM). Thus, we explored the interactions among blood endotoxin, UA, and LAC levels and the risk of T2DM.

METHODS

This population-based cross-sectional study included 2520 Chinese adults. Fasting blood endotoxin, UA, and LAC levels were determined and the cut-off values were obtained from the receiver operating characteristic curve analysis. The study population was classified into two or four subgroups based on low or high, or both low and high levels of endotoxin, UA, and LAC, respectively.

RESULTS

The odds ratios (ORs) for T2DM (all P < .05) were higher in the high groups than the low groups of endotoxin, UA, or LAC, respectively. Participants in the groups with high levels of both endotoxin and UA, endotoxin and LAC, or UA and LAC, had 4.71 (95% CI 3.01-7.37), 5.13 (95% CI 3.29-7.99), or 3.73 (95% CI 2.34-5.94) times higher risk for T2DM compared to those in groups with low levels of both endotoxin and UA, endotoxin and LAC, or UA and LAC (all P < 0.05), respectively. In the interaction analysis, an interactive effect between endotoxin and UA (P < .05), or endotoxin and LAC (P < .05), but not UA and LAC, was observed that contributed to an increased risk of T2DM.

CONCLUSIONS

The interaction between levels of endotoxin and UA or levels of endotoxin and LAC was related to an increased risk of T2DM in the Chinese population.

Lactate Levels with Chronic Metformin Use: A Narrative Review

Metformin has been associated with lactic acidosis. Lactate levels are not commonly tested in clinical practice, and it is unclear to what extent metformin would typically increase lactate levels with chronic use. The aim of this review was to determine whether regular monitoring of the plasma lactate level would be beneficial in avoiding lactate accumulation and, ultimately, minimising the incidence of lactic acidosis in metformin-treated patients.A comprehensive search of PubMed, Embase, Web of Science, Cochrane and International Pharmaceutical Abstracts databases covering the period up to 30 May 2017 was performed. Search terms included combinations of terms and keywords, including "metformin", "lactate", "lactic acid" and "lactic acidosis". Cases series of lactic acidosis or metformin-associated lactic acidosis were excluded.Of 1539 potentially relevant articles, a total of 52 reported lactate levels from routine/regular pathological tests in metformin users. The studies were subdivided into four themes, regarding metformin usage and the reported lactate levels in patients who: (1) did not have contraindications to the use of metformin; (2) had contraindications, or renal impairment but without other contraindications; (3) exercised; or (4) also received any nucleoside reverse transcriptase inhibitor. Studies have reported that metformin treatment could increase lactate level of users. However, most results showed that the lactate level remained in the normal range.No definitive conclusions on the benefits of regular lactate monitoring in patients taking metformin can be made. Future research on larger populations focusing on the measurement of lactate levels with continuous metformin use is warranted.

GCKR and PPP1R3B identified as genome-wide significant loci for plasma lactate: the Atherosclerosis Risk in Communities (ARIC) study

AIM

To investigate the genetic influence of circulating lactate level, a marker of oxidative capacity associated with diabetes.

METHODS

We conducted a genome-wide association study of log-transformed plasma lactate levels in 6901 European-American participants in the Atherosclerosis Risk in Communities study. For regions that achieved genome-wide significance in European-American participants, we conducted candidate region analysis in African-American subjects and tested for interaction between metformin use and the index single nucleotide polymorphisms for plasma lactate in European-American subjects.

RESULTS

The genome-wide association study in European-American subjects identified two genome-wide significant loci, GCKR (rs1260326, T allele β=0.08; P=1.8×10(-47) ) and PPP1R3B/LOC157273 (rs9987289, A allele β=0.06; P=1.6×10(-9) ). The index single nucleotide polymorphisms in these two loci explain 3.3% of the variance in log-transformed plasma lactate levels among the European-American subjects. In the African-American subjects, based on a region-significant threshold, the index single nucleotide polymorphism at GCKR was associated with plasma lactate but that at PPP1R3B/LOC157273 was not. Metformin use appeared to strengthen the association between the index single nucleotide polymorphism at PPP1R3B/LOC157273 and plasma lactate in European-American subjects (P for interaction=0.01).

CONCLUSIONS

We identified GCKR and PPP1R3B/LOC157273 as two genome-wide significant loci of plasma lactate. Both loci are associated with other diabetes-related phenotypes. These findings increase our understanding of the genetic control of lactate metabolism.

Safety of metformin in patients with chronic obstructive pulmonary disease and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is commonly associated with chronic obstructive pulmonary disease (COPD). Metformin is a valuable treatment for T2DM, and may offer additional benefits in COPD. However, due to its rare association with lactic acidosis, its safety in COPD is uncertain. We retrospectively identified patients with T2DM who had been admitted to hospital for COPD exacerbations. We compared those who were taking metformin with those who were not, with respect to their lactate concentration (primary endpoint) and survival (secondary endpoint). The study cohort (n = 130) had a mean (±standard deviation) age of 73.0 ± 9.8 years and 47 (36%) were female. Arterial blood gases were recorded in 120 cases: 88 (73%) were hypoxemic, 45 (38%) were in respiratory failure and 33 (28%) had respiratory acidosis. The 51 patients (39%) in the metformin group had a median (interquartile range) lactate concentration of 1.45 mmol/L (1.10-2.05) versus 1.10 mmol/L (0.80-1.50) in the non-metformin group (p = 0.012). Median survival was 5.2 years (95% CI 4.5-5.8) versus 1.9 years (1.1-2.6), respectively (hazard ratio 0.57; 95% CI 0.35-0.94). This remained significant in a multivariate model adjusted for measurable confounders. In conclusion, among patients with COPD at high risk for lactate accumulation, metformin therapy was associated with a minor elevation of lactate concentration of doubtful clinical significance. Metformin was associated with a survival benefit, but this must be interpreted cautiously due to possible effects from unmeasured confounders. Viewed collectively, the results suggest that COPD should not present a barrier to the investigational or clinical use of metformin.

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.

The comparison of muscle strength and short-term endurance in the different periods of type 2 diabetes

Background

Patients with type 2 diabetes (T2DM) are subjected to reduction in the quality and oxidative capacity of muscles. The effect of duration of diabetes on the muscle endurance response is not clear and strength as well.

Objective

The aim of this study was the assessment of strength and endurance of knee extensor and flexor in the patients with T2DM < 10 and T2DM > 10 years in comparison with age, sex, BMI, ABI and PAI-matched health control subjects.

Methods

Isometric maximal peak torque (MPT) of knee extensor and flexor before and after 40 isokinetic repetitions with velocity of 150 degree/s were recorded in 18 patients with T2DM < 10 Y , 12 patients with T2DM > 10 Y and 20 matched health control (HC) groups.

Results

Both diabetic patient groups had significant lower isometric and isotonic knee extensor and flexor strength than HC. The endurance indices indicated that whereas the isometric MPT of flexor movement was reduced after isokinetic protocol in the both patient groups in comparison with HC, the less decline was seen in the isotonic torque and work during isokinetic protocol in the T2DM > 10 Y group in comparison with two other groups. The HbA1c and FPG were significantly correlated with strength not with endurance indices.

Conclusions

It seems the progression of diabetes accompanied with vascular, neural and muscular deficits activate, some adaptive and compensatory processes which can maintain muscle performance.