Serum bicarbonate concentration and the risk of cardiovascular disease and death in type 2 diabetes: the Fremantle Diabetes Study

Serum/plasma biomarkers and the progression of cardiometabolic multimorbidity: a systematic review and meta-analysis

Background

The role of certain biomarkers in the development of single cardiometabolic disease (CMD) has been intensively investigated. Less is known about the association of biomarkers with multiple CMDs (cardiometabolic multimorbidity, CMM), which is essential for the exploration of molecular targets for the prevention and treatment of CMM. We aimed to systematically synthesize the current evidence on CMM-related biomarkers.

Methods

We searched PubMed, Embase, Web of Science, and Ebsco for relevant studies from inception until August 31st, 2022. Studies reported the association of serum/plasma biomarkers with CMM, and relevant effect sizes were included. The outcomes were five progression patterns of CMM: (1) no CMD to CMM; (2) type 2 diabetes mellitus (T2DM) followed by stroke; (3) T2DM followed by coronary heart disease (CHD); (4) T2DM followed by stroke or CHD; and (5) CHD followed by T2DM. Newcastle-Ottawa Quality Assessment Scale (NOS) was used to assess the quality of the included studies. A meta-analysis was conducted to quantify the association of biomarkers and CMM.

Results

A total of 68 biomarkers were identified from 42 studies, which could be categorized into five groups: lipid metabolism, glycometabolism, liver function, immunity, and others. Lipid metabolism biomarkers were most reported to associate with CMM, including TC, TGs, HDL-C, LDL-C, and Lp(a). Fasting plasma glucose was also reported by several studies, and it was particularly associated with coexisting T2DM with vascular diseases. According to the quantitative meta-analysis, HDL-C was negatively associated with CHD risk among patients with T2DM (pooled OR for per 1 mmol/L increase = 0.79, 95% CI = 0.77-0.82), whereas a higher TGs level (pooled OR for higher than 150 mg/dL = 1.39, 95% CI = 1.10-1.75) was positively associated with CHD risk among female patients with T2DM.

Conclusion

Certain serum/plasma biomarkers were associated with the progression of CMM, in particular for those related to lipid metabolism, but heterogeneity and inconsistent findings still existed among included studies. There is a need for future research to explore more relevant biomarkers associated with the occurrence and progression of CMM, targeted at which is important for the early identification and prevention of CMM.

Serum bicarbonate concentration and the risk of death in type 2 diabetes: the Fremantle Diabetes Study Phase II

AIMS

To examine whether all-cause mortality is independently associated with serum bicarbonate concentration below the laboratory reference interval in a representative, well-characterised community-based cohort of people with type 2 diabetes.

METHODS

1478 FDS2 participants with type 2 diabetes (mean age 65.8 years, 51.6% males, median diabetes duration 9.0 years) from the longitudinal, observational Fremantle Diabetes Study Phase II (FDS2) were followed from study entry to death or end-2016. Independent associates of a low baseline serum bicarbonate (< 22 mmol/L) were determined using multiple logistic regression. The role of important covariates in influencing the association between bicarbonate and mortality was assessed by a stepwise Cox regression approach.

RESULTS

A low serum bicarbonate was associated with increased all-cause mortality in unadjusted analysis (hazard ratio (HR) 1.90 (95% confidence limits (CL) 1.39, 2.60 per mmol/L). Mortality remained significantly associated with low serum bicarbonate (HR 1.40 (95% CL 1.01, 1.94) per mmol/L) in a Cox regression model with adjustment for factors associated with mortality but not low serum bicarbonate, but inclusion of estimated glomerular filtration rate categories rendered the association non-significant (HR 1.16 (95% CL 0.83, 1.63) per mmol/L).

CONCLUSIONS

A low serum bicarbonate is not an independent prognostic marker in people with type 2 diabetes but it may be a manifestation of the pathway between the development of impaired renal function and death.

Hidden chronic metabolic acidosis of diabetes type 2 (CMAD): Clues, causes and consequences

Interpretation of existing data revealed that chronic metabolic acidosis is a pathognomic feature for type 2 diabetes (T2D), which is described here as "chronic metabolic acidosis of T2D (CMAD)" for the first time. The biochemical clues for the CMAD are summarised in the following; low blood bicarbonate (high anionic gap), low pH of interstitial fluid and urine, and response to acid neutralization, while the causes of extra protons are worked out to be; mitochondrial dysfunction, systemic inflammation, gut microbiota (GM), and diabetic lung. Although, the intracellular pH is largely preserved by the buffer system and ion transporters, a persistent systemic mild acidosis leaves molecular signature in cellular metabolism in diabetics. Reciprocally, there are evidences that CMAD contributes to the initiation and progression of T2D by; reducing insulin production, triggering insulin resistance directly or via altered GM, and inclined oxidative stress. The details about the above clues, causes and consequences of CMAD are obtained by searching literature spanning between 1955 and 2022. Finally, the molecular bases of CMAD are discussed in details by interpretation of an up-to-date data and aid of well constructed diagrams, with a conclusion unravelling that CMAD is a major player in T2D pathophysiology. To this end, the CMAD disclosure offers several therapeutic potentials for prevention, delay or attenuation of T2D and its complications.

Effect of sodium bicarbonate on cardiovascular outcome and mortality in patients with advanced chronic kidney disease

Background: Metabolic acidosis is a common complication in patients with chronic kidney disease (CKD). Oral sodium bicarbonate is often used to treat metabolic acidosis and prevent CKD progression. However, there is limited information about the effect of sodium bicarbonate on major adverse cardiovascular events (MACE) and mortality in patients with pre-dialysis advanced CKD. Method: 25599 patients with CKD stage V between January 1, 2001 and December 31, 2019 were identified from the Chang Gung Research Database (CGRD), a multi-institutional electronic medical record database in Taiwan. The exposure was defined as receiving sodium bicarbonate or not. Baseline characteristics were balanced using propensity score weighting between two groups. Primary outcomes were dialysis initiation, all-cause mortality, and major adverse cardiovascular events (MACE) (myocardial infarction, heart failure, stroke). The risks of dialysis, MACE, and mortality were compared between two groups using Cox proportional hazards models. In addition, we performed analyzes using Fine and Gray sub-distribution hazard models that considered death as a competing risk. Result: Among 25599 patients with CKD stage V, 5084 patients (19.9%) were sodium bicarbonate users while 20515 (80.1%) were sodium bicarbonate non-users. The groups had similar risk of dialysis initiation (hazard ratio (HR): 0.98, 95% confidence interval (CI): 0.95-1.02, p < 0.379). However, taking sodium bicarbonate was associated with a significantly lower risks of MACE (HR: 0.95, 95% CI 0.92-0.98, p < 0.001) and hospitalizations for acute pulmonary edema (HR: 0.92, 95% CI 0.88-0.96, p < 0.001) compared with non-users. The mortality risks were significantly lower in sodium bicarbonate users compared with sodium bicarbonate non-users (HR: 0.75, 95% CI 0.74-0.77, p < 0.001). Conclusion: This cohort study revealed that in real world practice, use of sodium bicarbonate was associated with similar risk of dialysis compared with non-users among patients with advanced CKD stage V. Nonetheless, use of sodium bicarbonate was associated with significantly lower rate of MACE and mortality. Findings reinforce the benefits of sodium bicarbonate therapy in the expanding CKD population. Further prospective studies are needed to confirm these findings.

Metabolic Acidosis Results in Sexually Dimorphic Response in the Heart Tissue

Metabolic acidosis (MA) is a highly prevalent disorder in a significant proportion of the population, resulting from imbalance in blood pH homeostasis. The heart, being an organ with very low regenerative capacity and high metabolic activity, is vulnerable to chronic, although low-grade, MA. To systematically characterize the effect of low-grade MA on the heart, we treated male and female mice with NH₄Cl supplementation for 2 weeks and analyzed their blood chemistry and transcriptomic signature of the heart tissue. The reduction of pH and plasma bicarbonate levels without an associated change in anion gap indicated a physiological manifestation of low-grade MA with minimal respiratory compensation. On transcriptomic analysis, we observed changes in cardiac-specific genes with significant gender-based differences due to MA. We found many genes contributing to dilated cardiomyopathy to be altered in males, more than in females, while cardiac contractility and Na/K/ATPase-Src signaling were affected in the opposite way. Our model presents a systems-level understanding of how the cardiovascular tissue is affected by MA. As low-grade MA is a common ailment with many dietary and pharmaceutical interventions, our work presents avenues to limit chronic cardiac damage and disease manifestation, as well as highlighting the sex differences in MA-induced cardiovascular damage.

Low Serum Bicarbonate Levels Increase the Risk of All-Cause, Cardiovascular Disease, and Cancer Mortality in Type 2 Diabetes

CONTEXT

The evidence regarding bicarbonate status and mortality among diabetes is scarce.

OBJECTIVE

The purpose of this study was to investigate the associations of bicarbonate concentrations with risk of all-cause, cardiovascular disease (CVD), and cancer mortality among patients with type 2 diabetes (T2D).

METHODS

This study included 8163 adult diabetic patients from the National Health and Nutrition Examination Survey (NHANES), 1999 to 2018. Death outcomes were ascertained by linkage to National Death Index records through 31 December 2019. The Cox proportional-risk model was used to estimate hazard ratios (HR) and 95% CIs for mortality from all causes, CVD, and cancer. The mediating effects of 11 metabolic, cardiovascular, and renal biomarkers were evaluated using a logistic regression model within a counterfactual framework.

RESULTS

During 8163 person-years of follow-up, 2310 deaths were documented, including 659 CVD deaths and 399 cancer deaths. After multivariate adjustment, lower serum bicarbonate levels were significantly linearly correlated with higher all-cause, CVD, and cancer mortality: The risk of all-cause death increased by 40%, the risk of CVD death increased by 48%, and the risk of cancer death increased by 84% compared with the normal group (all P < .05). Altered levels of estimated glomerular filtration rate explained 12.10% and 16.94% of the relation between serum bicarbonate with all-cause and CVD mortality, respectively. Total cholesterol mediated 4.70% and 10.51% of the associations of all-cause and CVD mortality, respectively.

CONCLUSION

Lower serum bicarbonate concentrations were significantly associated with higher all-cause, CVD, and cancer mortality. These findings suggest that maintaining adequate bicarbonate status may lower mortality risk in individuals with T2D.

Base excess is associated with the risk of all-cause mortality in critically ill patients with acute myocardial infarction

Background

Base excess (BE) represents an increase or decrease of alkali reserves in plasma to diagnose acid-base disorders, independent of respiratory factors. Current findings about the prognostic value of BE on mortality of patients with acute myocardial infarction (AMI) are still unclear. The purpose of this study was to explore the prognostic significance of BE for short-term all-cause mortality in patients with AMI.

Methods

A total of 2,465 patients diagnosed with AMI in the intensive care unit from the Medical Information Mart for Intensive Care III (MIMIC-III) database were included in our study, and we explored the association of BE with 28-day and 90-day all-cause mortality using Cox regression analysis. We also used restricted cubic splines (RCS) to evaluate the relationship between BE and hazard ratio (HR). The primary outcomes were 28-day and 90-day all-cause mortality.

Results

When stratified according to quantiles, low BE levels at admission were strongly associated with higher 28-day and 90-day all-cause mortality. Multivariable Cox proportional hazard models revealed that low BE was an independent risk factor of 28-day all-cause mortality [HR 4.158, 95% CI 3.203–5.398 (low vs. normal BE) and HR 1.354, 95% CI 0.896–2.049 (high vs. normal BE)] and 90-day all-cause mortality [HR 4.078, 95% CI 3.160–5.263 (low vs. normal BE) and HR 1.369, 95% CI 0.917–2.045 (high vs. normal BE)], even after adjustment for significant prognostic covariates. The results were also consistent in subgroup analysis. RCS revealed an “L-type” relationship between BE and 28-day and 90-day all-cause mortality, as well as adjusting for confounding variables. Meanwhile, Kaplan–Meier survival curves were stratified by combining BE with carbon dioxide partial pressure (PaCO2), and patients had the highest mortality in the group which had low BE (&lt; 3.5 mEq/L) and high PaCO2 (&gt; 45 mmHg) compared with other groups.

Conclusion

Our study revealed that low BE was significantly associated with 28-day and 90-day mortality in patients with AMI and indicated the value of stratifying the mortality risk of patients with AMI by BE.

Metabolic Acidosis and Cardiovascular Disease in CKD

Rationale & Objective

Metabolic acidosis related to chronic kidney disease (CKD) is associated with an accelerated decline in glomerular filtration rate (GFR) and the development of end-stage kidney disease. Whether metabolic acidosis is associated with cardiovascular (CV) events in patients with CKD is unclear.

Study Design

Retrospective cohort study.

Setting & Participants

The Optum De-identified Electronic Health Records Dataset, 2007–2017, was used to generate a cohort of patients with non-dialysis-dependent CKD who had at least 3 estimated GFR < 60 mL/min/1.73 m². Patients with metabolic acidosis (serum bicarbonate 12 to <22 mEq/L) or normal serum bicarbonate (22‒29 mEq/L) at baseline were identified by 2 consecutive measurements 28‒365 days apart.

Predictor

Serum bicarbonate as a continuous variable.

Outcome

Primary outcome was a composite of major adverse cardiovascular events (MACE+). Secondary outcomes included individual components of the composite outcome.

Analytical Approach

Cox proportional hazards models to evaluate the association between 1-mEq/L increments in serum bicarbonate and MACE+.

Results

A total of 51,558 patients were evaluated, 34% had metabolic acidosis. The median follow-up period was 3.9–4.5 years, depending on the outcome assessed. The adjusted hazard ratio (HR) for MACE+ was 0.964 (95% CI, 0.961–0.968). For the individual components of incident heart failure (HF), stroke, myocardial infarction (MI), and CV death, HRs were 0.98 (95% CI, 0.97–0.98), 0.98 (95% CI, 0.97–0.99), 0.96 (95% CI, 0.96–0.97), and 0.94 (95% CI, 0.93–0.94), respectively, for every 1-mEq/L increase in serum bicarbonate.

Limitations

Possible residual confounding.

Conclusions

Metabolic acidosis in CKD is associated with an increased risk of MACE+ as well as the individual components of incident HF, stroke, MI, and CV death. Randomized controlled trials evaluating treatments for the correction of metabolic acidosis in CKD to prevent CV events are needed.

Prevalence and risk factors of peripheral artery disease in a population with chronic kidney disease in Australia: A systematic review and meta-analysis

There is a lack of clarity and guidance for screening peripheral artery disease (PAD) in persons with chronic kidney disease (CKD) and end stage kidney disease (ESKD) despite this group being at excess risk of cardiovascular disease (CVD). In this current study, we performed a systematic review and meta-analysis to examine the prevalence and risk factors for PAD in persons with CKD in Australian cohorts. We used the inverse variance heterogeneity meta-analysis with double arcsine transformation to summarize the prevalence of PAD (with 95% CIs). Nine studies and 18 reports from the Australia and New Zealand dialysis and transplant registry with 36 cohorts were included in the review. We found a substantially higher PAD prevalence in cohorts based on an ankle-brachial index (ABI) or toe systolic pressure (TBI) than cohorts based on self-reported history. Higher PAD prevalence was observed in ESKD persons than CKD persons without dialysis (PAD diagnosis based on ABI or TBI: 31% in ESKD persons and 23% in CKD persons, PAD diagnosis based on self-reported history: 17% in ESKD persons and 10% in CKD persons). Older age, Caucasian race, cerebrovascular disease and haemodialysis were associated with the presence of PAD in ESKD persons. Our findings indicated a considerable proportion of PAD in CKD and ESKD persons particularly in those with ESKD. To develop and provide an adequate plan to clinically manage CKD patients with PAD, evidence of cost-effectiveness and clinical benefit of early detection of PAD in persons with CKD in Australia is recommended for future studies.

Serum bicarbonate and cardiovascular events in hypertensive adults: results from the Systolic Blood Pressure Intervention Trial

BACKGROUND

Low serum bicarbonate level is associated with increased mortality, but its role as a predictor of cardiovascular disease (CVD) is unclear. This study evaluates the association between serum bicarbonate concentration and CVD and whether the effect of intensive blood pressure (BP) lowering on CVD outcomes is modified by serum bicarbonate level.

METHODS

The Systolic Blood Pressure Intervention Trial (SPRINT) randomized participants to a systolic BP target <120 mmHg (intensive treatment) or <140 mmHg (standard treatment). The primary CVD outcome was a composite of nonfatal myocardial infarction (MI), acute coronary syndrome not resulting in MI, stroke, acute decompensated heart failure and CVD death. Cox proportional hazards models adjusted for demographic, clinical and laboratory characteristics were used to evaluate the association of interest in 9334 SPRINT participants (ClinicalTrials.gov: NCT01206062).

RESULTS

Over a median follow-up of 3.33 years (interquartile range 2.87-3.87 years), 618 (6.6%) participants experienced a primary CVD outcome. Participants with serum bicarbonate <22 mEq/L had a significantly higher risk of the primary CVD outcome (hazard ratio 1.54; 95% confidence interval 1.11-2.14, P = 0.01), compared with participants with bicarbonate 22-26 mEq/L. The magnitude of the CVD risk reduction with intensive BP lowering was similar across bicarbonate strata (P-value for interaction = 0.97).

CONCLUSIONS

In hypertensive individuals, serum bicarbonate level <22 mEq/L was associated with an increased CVD risk. The effect of intensive BP lowering on CVD outcomes was not modified by the serum bicarbonate level.

Serum Bicarbonate Concentration and Cause-Specific Mortality: The National Health and Nutrition Examination Survey 1999-2010

OBJECTIVE

To assess the association between serum bicarbonate concentration and cause-specific mortality in the US general population.

METHODS

A total of 31,195 individuals enrolled in the National Health and Nutrition Examination Survey between 1999 and 2010 were followed for a median 6.7 (interquartile range, 3.7-9.8) years. Cause-specific mortality was defined as cardiovascular, malignancy, and noncardiovascular/nonmalignancy causes. Cox proportional hazards adjusted for demographics, comorbidities, medications, and renal function were used to test the association between baseline serum bicarbonate and the outcomes of interest.

RESULTS

Of the 2798 participants who died, 722 had a cardiovascular- and 620 had a malignancy-related death. Compared with participants with serum bicarbonate 22 to 26 mEq/L, those with a level below 22 mEq/L had an increased hazard of all-cause and malignancy-related mortality (hazard ratio [HR], 1.54; 95% CI, 1.30-1.83; and HR, 1.46; 95% CI 1.00-2.13, respectively). The hazard for cardiovascular mortality was increased by 8% with each 1 mEq/L increase in serum bicarbonate above 26 mEq/L (HR, 1.08; 95% CI, 1.01-1.15). The findings were consistent in participants with or without chronic kidney disease, with no significant interactions observed.

CONCLUSION

In a large cohort of US adults, serum bicarbonate concentration level below 22 mEq/L was associated with malignancy-related mortality, whereas a concentration above 26 mEq/L was associated with cardiovascular mortality. Further studies to evaluate potential mechanisms for the differences in cause-specific mortality are warranted.

Screening and Risk Assessment of Coronary Artery Disease in Patients With Type 2 Diabetes: An Updated Review

Current literature indicates that there is a strong correlation between coronary artery disease (CAD) and type 2 diabetes. The arteriosclerotic progression occurs earlier and in a greater extent in the diabetic than in the non-diabetic population. In diabetic subjects, the detection of arterial disease does not always precede the development of an acute arterial incident. Herein, we reviewed studies published within the last 5 years in order to reveal the risk factors for coronary artery disease in patients with type 2 diabetes. In addition, we aimed to discuss how to diagnose in an early stage or even screen the presence of coronary artery disease in asymptomatic diabetic patients. Possible blood markers as predictors of CAD, which are mostly related to the lipidemic profile of subjects, are included in this review. Less invasive imaging methods than conventional coronary angiography, included in the article, are gradually used more in the diagnosis of CAD and show high effectiveness. Data from 23 articles with 22,350 patients having type 2 diabetes were summarized and presented descriptively.

Are low levels of serum bicarbonate associated with risk of progressing to impaired fasting glucose/diabetes? A single-centre prospective cohort study in Beijing, China

AIMS

Bicarbonate is involved in many human essential metabolic processes, but little is known about the association between serum bicarbonate and glucose metabolism. This study aims to investigate the association between serum bicarbonate and the risk of progressing to impaired fasting glucose (IFG)/diabetes mellitus (DM).

SETTING

The data were obtained from a large-scale prospective cohort study in a single health centre in Beijing.

PARTICIPANTS

A total of 5318 participants aged 18-70 years who underwent health examinations annually with baseline fasting plasma glucose (FPG) ranging from 3.9 to 5.5 mmol/L, without a history of either diabetes or concomitant chronic diseases, were enrolled in this 6-year observational study.

PRIMARY OUTCOME MEASURES

A logistic regression analysis was used to calculate ORs for progressing to IFG/DM by the category of baseline serum bicarbonate. In addition, an analysis of the receiver operating characteristic (ROC) curve for predicting IFG was performed.

RESULTS

Of the 5318 participants, 210 developed IFG after a median 2.2 years of follow-up. After adjusting for sex, age, FPG, body mass index, systolic blood pressure, serum creatinine, serum alanine aminotransferase and low-density lipoprotein cholesterol at baseline, the participants in the first (OR 4.18, 95% CI 2.42 to 7.21; p<0.001), second (OR 3.02, 95% CI 1.71 to 5.33; p<0.001) and third (OR 2.12, 95% CI 1.15 to 3.89; p=0.015) quartiles of serum bicarbonate had higher odds for progressing to IFG/DM compared with those in the highest quartile. The area under the ROC curve for predicting IFG/DM was 0.69 (95% CI 0.65 to 0.72; p<0.001).

CONCLUSIONS

Lower serum bicarbonate is associated with higher risk of the development of IFG/DM.