Low glycated hemoglobin and liver disease in the U.S. population

U-shaped association between HbA1c and all-cause mortality in CVD patients with diabetes

In this analysis, the association of baseline glycated hemoglobin (HbA1c) levels with all-cause mortality in cardiovascular disease (CVD) patients with diabetes was investigated using data from NHANES 1999-2014. Under examination were 845 CVD patients who had diabetes and were followed for a median follow-up of 7.3 years, and an all-cause mortality rate of 22.60% was observed. To examine the association between HbA1c and mortality, multivariable Cox proportional hazard models using spline models determined the non-linear association. HbA1c as a continuous variable was not associated with mortality. However, a significant association was observed when HbA1c was classified according to quartiles. Particularly, after adjustment for potential confounders, in comparison to participants with HbA1c levels below 6.2%, patients with HbA1c levels of 6.2-6.8% and 6.9-7.6% had lower risks of all-cause mortality (hazard ratio: 0.49, 95% CI: 0.30-0.80 and hazard ratio: 0.64, 95% CI: 0.39-1.03, respectively). Using restricted cubic splines, further testing confirmed the lack of a linear association and instead suggested a U-shaped relationship between HbA1c and mortality, with an optimal HbA1c target value of 6.9%. A 1-unit increase in HbA1c with HbA1c less than or equal to 6.9% was predictive of a 55% reduction in all-cause mortality compared to HbA1c levels above 6.9%, which exhibited an elevation in risk. All told, these data suggest that the relationship between HbA1c and all-cause mortality in CVD patients with diabetes is non-linear and U-shaped, and therefore may suggest that individualization of glycemic control may be beneficial for this patient population.

Anemia and its association with glycemia and transaminitis in patients with type 2 diabetes mellitus: A cross-sectional pilot study

Background and Aims

Anemia impairs glucose homeostasis, affects glycemic control, and predisposes to complications in diabetics. It correlates with oxidative stress and increases the risk of developing microvascular and macrovascular complications. However, it is an underrecognized comorbidity in diabetics. This study was conducted to assess the prevalence of anemia in diabetic patients and compare the metabolic profiles of anemic and non-anemic diabetics.

Methods

This is a cross-sectional study, conducted among type 2 diabetes (T2DM) patients, at the outpatient clinic. Patients with chronic kidney disease (CKD), known hematological disorders, and chronic inflammatory disorders were excluded.

Results

Of the 97 patients, 37 (38.14%) were found to be anemic (hemoglobin (Hb): male <13 g/dl, female <12 g/dl). The mean values of fasting blood sugar (FBS) in low and normal mean corpuscular volume (MCV) patients were 265.9 ± 43.7 mg/dl and 157.2 ± 7.2 mg/dl, respectively (P = 0.0026), and those of postprandial blood sugar (PPBS) were 370.3 ± 58.4 mg/dl and 226.3 ± 10.1 mg/dl, respectively (P = 0.0015). It was found that 6 (22.2%) of 27 patients with raised alanine aminotransferase (ALT) had anemia against 27 (45.8%) of 59 patients with normal ALT (P = 0.03). The mean Hb levels in patients with raised and normal ALT were 13.31 ± 2.3 gm% and 12.2 ± 2.0 gm% (P = 0.03), respectively.

Conclusions

Blood sugar may have a direct relationship with MCV in T2DM patients. Hb tends to relate to hepatic enzymes likely due to altered dietary patterns in anemics. Further larger studies on the effect of iron supplementation and dietary habits on glycemic control and hepatic steatosis are warranted.

Do iron homeostasis biomarkers mediate the associations of liability to type 2 diabetes and glycemic traits in liver steatosis and cirrhosis: a two-step Mendelian randomization study

BACKGROUND

Previous studies, including Mendelian randomization (MR), have demonstrated type 2 diabetes (T2D) and glycemic traits are associated with increased risk of metabolic dysfunction-associated steatotic liver disease (MASLD). However, few studies have explored the underlying pathway, such as the role of iron homeostasis.

METHODS

We used a two-step MR approach to investigate the associations of genetic liability to T2D, glycemic traits, iron biomarkers, and liver diseases. We analyzed summary statistics from various genome-wide association studies of T2D (n = 933,970), glycemic traits (n ≤ 209,605), iron biomarkers (n ≤ 246,139), MASLD (n ≤ 972,707), and related biomarkers (alanine aminotransferase (ALT) and proton density fat fraction (PDFF)). Our primary analysis was based on inverse-variance weighting, followed by several sensitivity analyses. We also conducted mediation analyses and explored the role of liver iron in post hoc analysis.

RESULTS

Genetic liability to T2D and elevated fasting insulin (FI) likely increased risk of liver steatosis (ORliability to T2D: 1.14 per doubling in the prevalence, 95% CI: 1.10, 1.19; ORFI: 3.31 per log pmol/l, 95% CI: 1.92, 5.72) and related biomarkers. Liability to T2D also likely increased the risk of developing liver cirrhosis. Genetically elevated ferritin, serum iron, and liver iron were associated with higher risk of liver steatosis (ORferritin: 1.25 per SD, 95% CI 1.07, 1.46; ORliver iron: 1.15 per SD, 95% CI: 1.05, 1.26) and liver cirrhosis (ORserum iron: 1.31, 95% CI: 1.06, 1.63; ORliver iron: 1.34, 95% CI: 1.07, 1.68). Ferritin partially mediated the association between FI and liver steatosis (proportion mediated: 7%, 95% CI: 2-12%).

CONCLUSIONS

Our study provides credible evidence on the causal role of T2D and elevated insulin in liver steatosis and cirrhosis risk and indicates ferritin may play a mediating role in this association.

Terminal trajectory of HbA1c for 10 years supports the HbA1c paradox: a longitudinal study using Health and Retirement Study data

Objectives

We aimed to assess the potential time-varying associations between HbA1c and mortality, as well as the terminal trajectory of HbA1c in the elderly to reveal the underlying mechanisms.

Design

The design is a longitudinal study using data from the Health and Retirement Study.

Setting and participants

Data were from the Health and Retirement Study. A total of 10,408 participants aged ≥50 years with available HbA1c measurements at baseline (2006/2008) were included.

Methods

Longitudinal HbA1c measured at 2010/2012 and 2014/2016 were collected. HbA1c values measured three times for their associations with all-cause mortality were assessed using Cox regression and restricted cubic splines. HbA1c terminal trajectories over 10 years before death were analyzed using linear mixed-effect models with a backward time scale.

Results

Women constitute 59.6% of the participants with a mean age of 69 years, with 3,070 decedents during the follow-up (8.9 years). The mortality rate during follow-up was 29.5%. Increased mortality risk became insignificant for the highest quartile of HbA1c compared to the third quartile (aHR 1.148, 1.302, and 1.069 for a follow-up of 8.9, 6.5, and 3.2 years, respectively) with a shorter follow-up, while it became higher for the lowest quartile of HbA1c (aHR 0.986, 1.068, and 1.439 for a follow-up of 8.9, 6.5, and 3.2 years, respectively). Accordingly, for both decedents with and without diabetes, an initial increase in HbA1c was followed by an accelerating terminal decline starting 5-6 years before death.

Conclusions and implications

The time-varying association between HbA1c and mortality mapped to the terminal trajectory in HbA1c. High and low HbA1c may have different clinical relationships with mortality. The HbA1c paradox may be partially explained by reverse causation, namely, early manifestation of death.

Longitudinal proteomics study of serum changes after allogeneic HSCT reveals potential markers of metabolic complications related to aGvHD

Even though hematopoietic stem cell transplantation (HSCT) allows successful treatment for many malignant and non-malignant disorders, its curative potential remains limited by severe side effects, including infections and other transplant-related complications such as graft-versus-host disease (GvHD). This study examined changes in serum proteome via high-performance two-dimensional gel electrophoresis (2-DE) during HSCT to search for diagnostic biomarkers for post-HSCT complications. Longitudinal proteomic analysis revealed proteins related to metabolic complications and hemolytic anemia. Retinol-binding protein 4 (RBP4), a reliable marker of insulin resistance, was identified, and is possibly associated with the onset mechanism of acute graft-versus-host disease (aGvHD) and/or skin GvHD. Although the cause of insulin resistance is not fully understood, it is thought to be associated with adipocytes inflammation induced by RBP4, iron overload and hemolytic anemia after HSCT, as observed in this study. The present study has demonstrated that insulin resistance and metabolic complications could be immediate complications after transplantation and are associated with aGvHD. The biomarkers revealed in this study are promising tools to be used for improving the early diagnosis of HSCT-associated complications, especially aGvHD, possibly even before clinical manifestations.

Association between haemoglobin A1c and all-cause and cause-specific mortality in middle-aged and older Koreans: a prospective cohort study

Background

This study aimed to examine associations between haemoglobin A1c (HbA1c) levels over time and all-cause and cause-specific mortality in middle-aged and older Koreans.

Methods

Using 16 years of follow-up data from the Korean Genome and Epidemiology Study, we analysed 9294 individuals aged 40–69 years with no history of cardiovascular disease (CVD) or cancer. Participants were divided into a known diabetes group and five groups categorized by HbA1c levels (< 5.0%, 5.0–5.4%, 5.5–5.9%, 6.0–6.4%, and ≥ 6.5%). Hazard ratios (HRs) for all-cause and cause-specific mortality associated with HbA1c levels were calculated using a conventional and a time-dependent Cox proportional hazards model. Restricted cubic spline models were fitted to investigate the relationship between continuous HbA1c levels and mortality among people without known diabetes. Subgroup analyses were performed for age, sex, smoking, hypertension, liver diseases, and red blood cell counts.

Results

During a median follow-up period of 15.7 years, there were 944 deaths, including 185 deaths from CVD, 359 from cancer, and 125 from all external causes. Compared with participants with HbA1c levels of 5.5–5.9%, multivariate-adjusted HRs and 95% confidence intervals for all-cause death of participants with levels < 5.0%, 5.0–5.4%, 6.0–6.4%, and ≥ 6.5% and participants with known diabetes were 1.84 (1.35–2.51), 1.13 (0.95–1.34), 1.30 (1.04–1.62), 1.37 (0.97–1.93), and 2.03 (1.70–2.44), respectively. The risk of cancer mortality was significantly increased in HbA1c < 5.0% (HR, 2.21; 95% CI 1.42–3.44) and known diabetes (HR, 1.60; 95% CI 1.18–2.15). When we performed diverse subgroup analyses, low HbA1c levels at baseline were strongly associated with mortality in participants with liver diseases.

Conclusions

We found U-shaped associations between HbA1c levels at baseline and over time and all-cause mortality in middle-aged and older Koreans. Additionally, the risk of cancer mortality increased both in low and high HbA1c groups, but CVD mortality increased only in high HbA1c group. In particular, people with liver diseases and low HbA1c levels had a high risk of all-cause mortality. Therefore, more careful management of these groups is suggested to identify any deteriorating health conditions.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00682-4.

Glycemic Control and Risk of Sepsis and Subsequent Mortality in Type 2 Diabetes

OBJECTIVE

To investigate the nature of the relationship between HbA1c and sepsis among individuals with type 2 diabetes, and to assess the association between sepsis and all-cause mortality in such patients.

RESEARCH DESIGN AND METHODS

We included 502,871 individuals with type 2 diabetes recorded in the Swedish National Diabetes Register and used multivariable Cox regression and restricted cubic spline analyses to assess the association between time-updated HbA1c values and sepsis occurrence between 1 January 2005 and 31 December 2015. The association between sepsis and death was examined using multivariable Cox regression analysis.

RESULTS

Overall, 14,534 (2.9%) patients developed sepsis during the study period. On multivariable Cox regression analysis, compared with an HbA1c of 48-52 mmol/mol (6.5-6.9%), the adjusted hazard ratio for sepsis was 1.15 (95% CI 1.07-1.24) for HbA1c <43 mmol/mol (6.1%), 0.93 (0.87-0.99) for HbA1c 53-62 mmol/mol (7.0-7.8%), 1.05 (0.97-1.13) for HbA1c 63-72 mmol/mol (7.9-8.7%), 1.14 (1.04-1.25) for HbA1c 73-82 mmol/mol (8.8-9.7%), and 1.52 (1.37-1.68) for HbA1c >82 mmol/mol (9.7%). In the cubic spline model, a reduction of the adjusted risk was observed within the lower HbA1c range until 53 mmol/mol (7.0%), with a hazard ratio of 0.78 (0.73-0.82) per SD; it increased thereafter (P for nonlinearity <0.001). As compared with patients without sepsis, the adjusted hazard ratio for death among patients with sepsis was 4.16 (4.03-4.30).

CONCLUSIONS

In a nationwide cohort of individuals with type 2 diabetes, we found a U-shaped association between HbA1c and sepsis and a fourfold increased risk of death among those developing sepsis.

Prognostic Value of Stress Hyperglycemia in Patients Admitted to Medical/Geriatric Departments for Acute Medical Illness

INTRODUCTION

Hyperglycemia is common in patients admitted to Italian medical/geriatric units and is associated with a poorer outcome. We tested the significance of diabetes and stress-induced hyperglycemia in clinical outcome.

MATERIALS AND METHODS

Three hundred seventy-eight consecutive patients with hyperglycemia at entry (≥ 126 mg/dl) (206 without known diabetes) were included, with a wide range of underlying diseases requiring hospital admission and independent of the presence of diabetes. Relative hyperglycemia was calculated as admission glucose divided by average glucose, estimated based of glycosylated hemoglobin. Values ≥ 1.20 were considered indicative of stress hyperglycemia (SHR). The association of SHR with outcome variables (all-cause complications, infections, non-infectious events, deaths) was tested by logistic regression analysis, adjusted for sex, BMI, age-adjusted comorbidities (Charlson index) and known diabetes.

RESULTS

During hospital stay, one or more events were registered in 96 patients (25.4%); 44 patients died in hospital, and fatality rate was borderline higher in patients without diabetes (14.6% vs. 8.1% in diabetes; P = 0.052) and nearly three times higher in patients with stress hyperglycemia (15.0%) vs. those with SHR < 1.2 (P = 0.005). Stress hyperglycemia-more common in the absence of diabetes (71% vs. 58%)-and age were the only independent prognostic factors for death. At multivariable analysis, the risks of death (OR 4.31, 95% CI 1.25-14.81), of all complications (OR 5.90, 95% CI 2.22-15.71) and of newly developed systemic infections (OR 5.67, 95% CI 1.61-19.92) were associated with stress hyperglycemia in subjects without diabetes, as was the risk in non-insulin-treated cases (OR 4.02, 95% CI 1.16-13.92; OR 5.47, 95% CI 2.21-13.52; OR 5.15, 95% CI 1.70-15.62, respectively).

CONCLUSION

The study confirms the prognostic value of stress-related hyperglycemia in patients requiring hospital admission to a geriatric/medical unit for a variety of acute medical conditions, contributing to adverse outcomes not limited to events commonly associated with hyperglycemia (e.g., infections).

Low HbA1c levels and all-cause or cardiovascular mortality among people without diabetes: the US National Health and Nutrition Examination Survey 1999-2015

OBJECTIVE

It is unclear whether relatively low glycated haemoglobin (HbA1c) levels are beneficial or harmful for the long-term health outcomes among people without diabetes. We aimed to investigate the association between low HbA1c levels and mortality among the US general population.

METHODS

This study includes a nationally representative sample of 39 453 US adults from the National Health and Nutrition Examination Surveys 1999-2014, linked to mortality data through 2015. We employed the parametric g-formula with pooled logistic regression models and the ensemble machine learning algorithms to estimate the time-varying risk of all-cause and cardiovascular mortality by HbA1c categories (low, 4.0 to <5.0%; mid-level, 5.0 to <5.7%; prediabetes, 5.7 to <6.5%; and diabetes, ≥6.5% or taking antidiabetic medication), adjusting for 72 potential confounders including demographic characteristics, lifestyle, biomarkers, comorbidities and medications.

RESULTS

Over a median follow-up of 7.5 years, 5118 (13%) all-cause deaths, and 1116 (3%) cardiovascular deaths were observed. Logistic regression models and machine learning algorithms showed nearly identical predictive performance of death and risk estimates. Compared with mid-level HbA1c, low HbA1c was associated with a 30% (95% CI, 16 to 48) and a 12% (95% CI, 3 to 22) increased risk of all-cause mortality at 5 years and 10 years of follow-up, respectively. We found no evidence that low HbA1c levels were associated with cardiovascular mortality risk. The diabetes group, but not the prediabetes group, also showed an increased risk of all-cause mortality.

CONCLUSIONS

Using the US national database and adjusting for an extensive set of potential confounders with flexible modelling, we found that adults with low HbA1c were at increased risk of all-cause mortality. Further evaluation and careful monitoring of low HbA1c levels need to be considered.

Metabolic Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder leading to paralysis, muscle atrophy, and death. Significant advances in antisense oligonucleotide treatment and gene therapy have made it possible for SMA patients to benefit from improvements in many aspects of the once devastating natural history of the disease. How the depletion of survival motor neuron (SMN) protein, the product of the gene implicated in the disease, leads to the consequent pathogenic changes remains unresolved. Over the past few years, evidence toward a potential contribution of gastrointestinal, metabolic, and endocrine defects to disease phenotype has surfaced. These findings ranged from disrupted body composition, gastrointestinal tract, fatty acid, glucose, amino acid, and hormonal regulation. Together, these changes could have a meaningful clinical impact on disease traits. However, it is currently unclear whether these findings are secondary to widespread denervation or unique to the SMA phenotype. This review provides an in-depth account of metabolism-related research available to date, with a discussion of unique features compared to other motor neuron and related disorders.

Glycaemic markers and all-cause mortality in older adults with and without diabetes: the Atherosclerosis Risk in Communities (ARIC) study

AIMS/HYPOTHESIS

There is controversy regarding the performance of HbA1c in old age. We evaluated the prognostic value of HbA1c and other glycaemic markers (fructosamine, glycated albumin, fasting glucose) with mortality risk in older adults (66-90 years).

METHODS

This was a prospective analysis of 5636 participants (31% with diagnosed diabetes, mean age 76, 58% female, 21% black) in the Atherosclerosis Risk in Communities (ARIC) study, baseline 2011-2013. We used Cox regression to examine associations of glycaemic markers (modelled in categories) with mortality risk, stratified by diagnosed diabetes status.

RESULTS

During a median of 6 years of follow-up, 983 deaths occurred. Among older adults with diabetes, 30% had low HbA1c (<42 mmol/mol [<6.0%]) and 10% had high HbA1c (≥64 mmol/mol [≥8.0%]); low (HR 1.32 [95% CI 1.04, 1.68]) and high (HR 1.86 [95% CI 1.32, 2.62]) HbA1c were associated with mortality risk vs HbA1c 42-52 mmol/mol (6.0-6.9%) after demographic adjustment. Low fructosamine and glycated albumin were not associated with mortality risk. Both low and high fasting glucose were associated with mortality risk. After further adjustment for lifestyle and clinical risk factors, high HbA1c (HR 1.81 [95% CI 1.28, 2.56]), fructosamine (HR 1.96 [95% CI 1.43-2.69]), glycated albumin (HR 1.81 [95% CI 1.33-2.47]) and fasting glucose (HR 1.81 [95% CI 1.24, 2.66]) were associated with mortality risk. Low HbA1c and fasting glucose were no longer significantly associated with mortality risk. Among participants without diabetes, associations of glycaemic markers with mortality risk were less robust.

CONCLUSIONS/INTERPRETATION

Elevated HbA1c, fructosamine, glycated albumin and fasting glucose were associated with risk of mortality in older adults with diabetes. Low HbA1c and fasting glucose may be markers of poor prognosis but are possibly confounded by health status. Our findings support the clinical use of HbA1c in older adults with diabetes. Graphical abstract.

Thiazolidinediones reduce the risk of hepatocellular carcinoma and hepatic events in diabetic patients with chronic hepatitis B

Thiazolidinediones (TZDs) improve glycaemic control and ameliorate liver steatosis, inflammation and fibrosis in patients with fatty liver disease. We aimed to study the impact of TZD and glycaemic control on the risk of hepatocellular carcinoma (HCC) and hepatic events in diabetic patients with chronic hepatitis B (CHB). We performed a retrospective cohort study on diabetic patients with CHB in 2000-2017 using a territory-wide electronic healthcare database in Hong Kong. Diabetes mellitus was identified by use of any antidiabetic medication, haemoglobin A1c (HbA1c ) ≥6.5%, fasting glucose ≥7 mmol/L in two measurements or ≥11.1 mmol/L in one measurement and/or diagnosis codes. Use of antidiabetic medications was modelled as time-dependent covariates. Of 28 999 diabetic patients with CHB, 3963 (13.7%) developed liver-related events (a composite endpoint of HCC and hepatic events) at a median (interquartile range) follow-up of 7.1 (3.7-11.8) years; 1153 patients received TZD during follow-up. After adjusted for important confounders, TZD use was associated with a reduced risk of liver-related events (adjusted hazard ratio [aHR] 0.46, 95% confidence interval [CI] 0.24-0.88; P = .019). Similar trends were observed in HCC (aHR 0.57) and hepatic events (aHR 0.35) separately. Compared to HbA1c of 6.5% at baseline, patients with HbA1c ≥7% had an increased risk of liver-related events; the risk further increased in 5795 (20.0%) patients with HbA1c ≥9% at baseline (aHR 1.14, 95% CI 1.04-1.26; P = .006). TZD use is associated with a lower risk of liver-related events in diabetic patients with CHB. Liver-related events are more common in patients with high HbA1c levels.

Glycated Hemoglobin and All-Cause and Cause-Specific Mortality Among Adults With and Without Diabetes

CONTEXT

The patterns of associations between glycated Hb (HbA1c) and mortality are still unclear.

OBJECTIVE

To explore the extent to which ranges of HbA1c levels are associated with the risk of mortality among participants with and without diabetes.

DESIGN, SETTING, AND PATIENTS

This was a nationwide, community-based prospective cohort study. Included were 15,869 participants (median age 64 years) of the Health and Retirement Study, with available HbA1c data and without a history of cancer. Cox proportional hazards regression models were used to estimate hazard ratios with 95% CIs for mortality.

RESULTS

A total of 2133 participants died during a median follow-up of 5.8 years. In participants with diabetes, those with an HbA1c level of 6.5% were at the lowest risk of all-cause mortality. When HbA1c level was <5.6% or >7.4%, the increased all-cause mortality risk became statistically significant as compared with an HbA1c level of 6.5%. As for participants without diabetes, those with an HbA1c level of 5.4% were at the lowest risk of all-cause mortality. When the HbA1c level was <5.0%, the increased all-cause mortality risk became statistically significant as compared with an HbA1c level of 5.4%. However, we did not observe a statistically significant elevated risk of all-cause mortality above an HbA1c level of 5.4%.

CONCLUSIONS

A U-shaped and reverse J-shaped association for all-cause mortality was found among participants with and without diabetes. The corresponding optimal ranges for overall survival are predicted to be 5.6% and 7.4% and 5.0% and 6.5%, respectively.

Abnormal fatty acid metabolism is a core component of spinal muscular atrophy

OBJECTIVE

Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder leading to paralysis and subsequent death in young children. Initially considered a motor neuron disease, extra-neuronal involvement is increasingly recognized. The primary goal of this study was to investigate alterations in lipid metabolism in SMA patients and mouse models of the disease.

METHODS

We analyzed clinical data collected from a large cohort of pediatric SMA type I-III patients as well as SMA type I liver necropsy data. In parallel, we performed histology, lipid analysis, and transcript profiling in mouse models of SMA.

RESULTS

We identify an increased susceptibility to developing dyslipidemia in a cohort of 72 SMA patients and liver steatosis in pathological samples. Similarly, fatty acid metabolic abnormalities were present in all SMA mouse models studied. Specifically, Smn2B/- mice displayed elevated hepatic triglycerides and dyslipidemia, resembling non-alcoholic fatty liver disease (NAFLD). Interestingly, this phenotype appeared prior to denervation.

INTERPRETATION

This work highlights metabolic abnormalities as an important feature of SMA, suggesting implementation of nutritional and screening guidelines in patients, as such defects are likely to increase metabolic distress and cardiovascular risk. This study emphasizes the need for a systemic therapeutic approach to ensure maximal benefits for all SMA patients throughout their life.

Low fasting glucose and future risks of major adverse outcomes in people without baseline diabetes or cardiovascular disease: a systematic review and meta-analysis

OBJECTIVE

To investigate the link between low fasting blood glucose levels and all-cause mortality and cardiovascular outcomes among people without baseline diabetes or cardiovascular disease.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed and Embase (1966-February 2019).

SELECTION CRITERIA

Prospective cohort studies were included for meta-analysis if they reported adjusted HRs with 95% CIs for associations between risk of all-cause mortality, stroke, major cardiovascular events, coronary heart disease and low fasting glucose levels (<4.6 mmol/L and/or 4.0 mmol/L, respectively) versus normal fasting glucose levels.

DATA EXTRACTION AND STATISTICAL ANALYSIS

Two independent reviewers extracted data from eligible studies. Heterogeneity was assessed by p value of χ² tests and I². We assessed four characteristics for each included study based on items developed by the US Preventive Task Force, as well as the modified checklist used in previous studies.

RESULTS

Eleven articles (consisting of 129 prospective cohort studies) with 2 674 882 participants without diabetes and cardiovascular disease at baseline were included in this meta-analysis. Pooled results from the random effects model showed increased risks of all-cause mortality (HR: 1.56; 95% CI 1.09 to 2.23), total stroke (HR: 1.08, 95% CI 1.03 to 1.13) and ischaemic stroke (HR: 1.06, 95% CI 1.01 to 1.10), and major cardiovascular events (HR: 1.05, 95% CI 1.03 to 1.07) among people with a fasting glucose <4.0 mmol/L, as compared with people with normal fasting glucose. The less stringent low fasting glucose level, <4.6 mmol/L, was not associated with increased risk of any endpoints.

DISCUSSION AND CONCLUSIONS

Among people without baseline diabetes or cardiovascular disease, a fasting blood glucose level of <4.0 mmol/L is associated with increased risk of all-cause mortality, major cardiovascular events and stroke.

Glycated Hemoglobin Levels in Patients with Decompensated Cirrhosis

Introduction. Aim of this study is to determine if HbA1c levels are a reliable predictor of glycemic control in patients with decompensated cirrhosis. Methods. 200 unique patients referred for liver transplantation at University of Tennessee/Methodist University Transplant Institute with a HbA1c result were included. Three glucose levels prior to the "measured" A1c (MA1c) were input into an HbA1c calculator from the American Diabetes Association website to determine the "calculated" A1c (CA1c). The differences between MA1c and CA1c levels were computed. Patients were divided into three groups: group A, difference of <0.5; group B, 0.51-1.5; and group C, >1.5. Results. 97 (49%) patients had hemoglobin A1c of less than 5%. Discordance between calculated and measured HbA1c of >0.5% was seen in 47% (n = 94). Higher level of discordance of greater than >1.5 was in 12% of patients (n = 24). Hemoglobin was an independent predictor for higher discordance (odds ratio 0.77 95%, CI 0.60-0.99, and p value 0.04). HbA1c was an independent predictor of occurrence of HCC (OR 2.69 955, CI 1.38-5.43, and p value 0.008). Conclusion. HbA1c is not a reliable predictor of glycemic control in patients with decompensated cirrhosis, especially in those with severe anemia.

What Clinical Laboratorians Should Do in Response to Extremely Low Hemoglobin A1c Results

Extremely low hemoglobin A1c (HbA1c) results below reference range are rare, and the causes and clinical implications associated with low HbA1c results are not well understood among clinical laboratorians. A case of extremely low HbA1c results was reported, in which liver cirrhosis, subacute hemorrhage and recent transfusion all contributed to the low result. This case illustrates when HbA1c should not be used as a clinically relevant diabetes marker. However, low or extremely low HbA1c (<5.0% or <4.0%) may occur in apparently healthy individuals. When this occurs, it is an independent risk factor associated with liver diseases, hospitalization, and all-cause mortality. From the clinical laboratory perspective, the clinical cause of extremely low HbA1c should be determined, and suggestions of different test utilization or increased health surveillance should be given to care providers.

High hemoglobin A1c levels within the non-diabetic range are associated with the risk of all cancers

Previous studies have reported associations between diabetes and cancer risk. However, specific association of hemoglobin A1c (HbA1c) levels with cancer risk remains inconclusive. We followed 29,629 individuals (11,336 men; 18,293 women) aged 46-80 years who participated in the Japan Public Health Center-based prospective study who had HbA1c measurements available and were cancer-free at baseline. Cancer incidence was assessed by systemic surveys. We estimated hazard ratios (HRs) for cancer risk with adjustment for age sex, geographic area, body mass index, smoking status, physical activity, alcohol, coffee, vegetable and total energy consumption, and history of cardiovascular disease. After a median follow-up of 8.5 years, 1,955 individuals had developed cancer. Higher HbA1c levels within both the non-diabetic and diabetic ranges in individuals without known diabetes were associated with overall cancer risk. Compared with individuals without known diabetes and HbA1c levels of 5.0-5.4%, the HRs for all cancers were 1.27 (95% confidence interval, 1.07-1.52); 1.01 (0.90-1.14); 1.28 (1.09-1.49); and 1.43 (1.14-1.80) for individuals without known diabetes and HbA1c levels <5.0%, 5.5-5.9%, 6.0-6.4%, and ≥6.5%, respectively, and 1.23 (1.02-1.47) for individuals with known diabetes. The lowest HbA1c group had the highest risk of liver cancer, and HbA1c levels were linearly associated with the risk of all cancers after excluding liver cancer (P for linear trend, 0.004). In conclusion, our findings corroborate the notion that glycemic control in individuals with high HbA1c levels may be important not only to prevent diabetes but also to prevent cancer.

Hb and dyslipidaemia as predicting markers of serum alanine aminotransferase elevation in Chinese adolescents

OBJECTIVE

Fe is an essential element for erythropoiesis and Hb synthesis. High Hb levels affect the blood's viscosity and are associated with cardiovascular dysfunction. The aim of the present study was to examine relationships of Hb and cardiometabolic abnormalities with the risk of alanine aminotransferase (ALT) elevation in adolescents.

DESIGN

A population-based, cross-sectional study.

SETTING

National Nutrition and Health Survey in Taiwan (2010-2011, adolescents).

SUBJECTS

Healthy adolescents aged 13-18 years.

RESULTS

In total, 1941 adolescents (963 boys and 978 girls) were entered in the study. The mean age was 15·3 (sd 0·1) years (boys, 15·3 (sd 0·1) years; girls, 15·2 (sd 0·1) years). ALT tertile cut-off points for boys were 11 and 16 U/l, and for girls were 9 and 12 U/l. Girls without dyslipidaemia and presenting in the highest quartile (Q1) of Hb (>13·6 g/dl) were 1·89 and 3·76 times more likely to have raised serum ALT (9 and >12 U/l, respectively) than the reference (lowest quartile of Hb (Q1), 12 U/l) than the reference (Q1 of Hb, 15·4 g/dl), who were 7·40 times more likely to have elevated serum ALT of >16 U/l than the reference (Q1 of Hb, <14·1 g/dl).

CONCLUSIONS

Our findings suggest that an increased Hb level is a predictor of elevated serum ALT in adolescent girls with dyslipidaemia. Our study also highlights the importance of further research to establish cut-off points for Hb and its utility in diagnosing and preventing the onset of dyslipidaemia in adolescents.

Fatty Liver and Fatty Heart—Where do They Stand in the AMIS Syndrome?

Meal-induced insulin sensitization (MIS) refers to the augmented glucose uptake response to insulin following a meal. Absence of MIS (AMIS) causes significant decrease in post-meal glucose disposal leading to postprandial hyperglycemia, hyperinsulinemia, hyperlipidemia, adiposity, increased free radical stress, and a cluster of progressive metabolic, vascular, and cardiac dysfunctions referred to as the AMIS syndrome. We tested the hypothesis that fat accumulation in the liver and heart is part of the AMIS syndrome. Questions examined in the study: (1) Is prediabetic fat accumulation in the heart and liver a component of the AMIS syndrome? (2) Is fatty liver a cause or consequence of peripheral insulin resistance? (3) Is early cardiac dysfunction in the AMIS syndrome attributable to fat accumulation in the heart? and (4) Can the synergistic antioxidant cocktail SAMEC (S-adenosylmethionine, vitamin E, and vitamin C), known to benefit MIS, affect cardiac and hepatic triglyceride levels? Four animal models of AMIS were used in aged male Sprague-Dawley rats (52 weeks ± sucrose ± SAMEC), compared with young controls (nine weeks). Fat accumulation in the heart was not significant and therefore cannot account for the early cardiac dysfunction. Hepatic triglycerides increased only in the most severe AMIS model but the small changes correlated with the much more rapidly developing peripheral adiposity. Systemic adiposity represents an early stage, whereas accumulation of cardiac and hepatic triglycerides represents a late stage of the prediabetic AMIS syndrome. Fat accumulation in the liver is a consequence, not a cause, of AMIS. SAMEC protected against the sucrose effects on whole body adiposity and hepatic lipid accumulation.

Hemoglobin a1c levels and the risk of cardiovascular disease in people without known diabetes: a population-based cohort study in Japan

High hemoglobin A1c (HbA1c) levels are strongly associated with an increased risk of cardiovascular disease (CVD) in people with and without diabetes. However, information regarding the relationship between low HbA1c levels and the risk of CVD among people without known diabetes is limited. The aim of this large-scale, prospective, population-based cohort study was to clarify the association between HbA1c levels and CVD risk among people without known diabetes.We followed-up 10,980 men and 18,079 women (46-80 years old and free of CVD and cancer at baseline) in the Japan Public Health Center-based Prospective Study. Using Cox models, we estimated the hazard ratios for CVD risk with adjustments for age, sex, geographic areas, body mass index, smoking status, sports and physical exercise, alcohol intake, systolic blood pressure, non-high-density lipoprotein cholesterol, and high-density lipoprotein cholesterol.During the median follow-up of 9.4 years, 935 CVD events (770 strokes and 165 coronary heart diseases) occurred. We observed a nonlinear association between HbA1c levels and CVD risk in participants without known diabetes. Compared with HbA1c levels of 5.0 to 5.4% (31-36 mmol/mol), the hazard ratios for CVD in participants without known diabetes were 1.50 (95% confidence interval: 1.15-1.95), 1.01 (0.85-1.20), 1.04 (0.82-1.32), and 1.77 (1.32-2.38) for HbA1c levels of <5.0% (<31 mmol/mol), 5.5 to 5.9% (37-41 mmol/mol), 6.0 to 6.4% (42-47 mmol/mol), and ≥6.5% (≥48 mmol/mol), respectively (P value for nonlinear trend: <0.001). In addition, the hazard ratio for CVD was 1.81 (1.43-2.29) in patients with known diabetes compared with participants with HbA1c levels of 5.0 to 5.4% and without known diabetes. This nonlinear relation persisted after excluding people with kidney dysfunction, liver dysfunction, anemia, body mass index <18.5 kg/m, or early events within 3 years of follow-up (P value for nonlinear trend: <0.01 for all tests).In conclusion, both low and high levels of HbA1c were associated with a higher risk of CVD in a Japanese general population without known diabetes.

Glycated hemoglobin and long-term prognosis in patients with suspected stable angina pectoris without diabetes mellitus: a prospective cohort study

OBJECTIVE

Associations of glycated hemoglobin A1c (HbA1c) levels to incident coronary and cardiovascular events among non-diabetic patients with coronary artery disease are unclear. We investigated relations of HbA1c to long-term prognosis in such patients.

METHODS

A prospective cohort of 2519 patients undergoing elective coronary angiography for suspected stable angina pectoris (SAP) was divided into pre-defined categories according to HbA1c (%) levels (<5.0, 5.0-5.6 (reference), 5.7-6.4), and followed for median 4.9 years. The primary end-point was major coronary events (including non-fatal and fatal acute myocardial infarctions, and sudden cardiac death). Secondary end-points were death from cardiovascular disease (CVD) and all-cause mortality. Hazard ratios (HRs) (95% confidence intervals [CIs]) were obtained by Cox regression.

RESULTS

Median age at inclusion was 62 years, 73% were males, median HbA1c was 5.6% and random plasma-glucose 5.4 mmol/L. After multivariate adjustment, HbA1c levels within the pre-diabetic range were not associated with risk of major coronary events, HR (95% CI): 1.13 (0.79-1.62); P=0.49, death from CVD or all-cause mortality HR (95% CI): 0.95 (0.55-1.66) and 1.04 (0.70-1.53), respectively; P≥0.85. Similarly, there was no significant association between HbA1c values within the lowest category and risk of study outcomes, (P≥0.18).

CONCLUSION

In non-diabetic patients with suspected SAP, there was no overall association between HbA1c levels and prognosis, questioning an independent role of glycemia in the pathogenesis of atherosclerotic complications in these patients.

Association between hemoglobin A1c and all-cause mortality: results of the mortality follow-up of the German National Health Interview and Examination Survey 1998

OBJECTIVE

This study examined the association of HbA1c-defined glycemic status and continuous HbA1c with all-cause mortality.

RESEARCH DESIGN AND METHODS

The study population comprised 6,299 participants (aged 18-79 years) of the German National Health Interview and Examination Survey 1998, who were followed up for mortality for an average of 11.6 years. Glycemic status was defined as known diabetes (self-reported diagnosis or intake of antidiabetic medication) and based on HbA1c levels according to American Diabetes Association diagnostic criteria as undiagnosed diabetes (≥6.5% [≥48 mmol/mol]), prediabetes with very high (6.0-6.4% [42-46 mmol/mol]) or high diabetes risk (5.7-5.9% [39-41 mmol/mol]), and normoglycemia (<5.7% [<39 mmol/mol]). Associations between glycemic status and mortality were examined by Cox regression adjusting for age, sex, education, lifestyle factors, anthropometric measures, and history of chronic diseases (reference: normoglycemia). Spline models were fitted to investigate associations between continuous HbA1c and mortality among participants without known diabetes.

RESULTS

Excess mortality risk was observed for participants with known diabetes (hazard ratio 1.41 [95% CI 1.08-1.84]) and undiagnosed diabetes (1.63 [1.23-2.17]) but not for those with high (1.02 [0.80-1.30]) or very high diabetes risk (0.87 [0.67-1.13]). Spline models revealed a U-shaped association, with lowest risk at HbA1c levels 5.4-5.6% (36-38 mmol/mol) and a significantly increased risk at ≤5.0% (≤31 mmol/mol) and ≥6.4% (≥46 mmol/mol).

CONCLUSIONS

Unlike known and undiagnosed diabetes, HbA1c levels in the prediabetic range were not associated with an increased mortality risk. The observed U-shaped relationship adds to existing evidence that not only high but also low HbA1c levels might be associated with all-cause mortality.

Type-2 diabetes and coronary heart disease: common physiopathology, viewed from autoimmunity

Two highly prevalent diseases, Type-2 diabetes mellitus and coronary heart disease (CHD), share risk factors. Excess levels of LDL-cholesterol have been overemphasized to uniformly encompass the development of CHD, and the origin of insulin resistance underlying Type-2 diabetes has not been fully elucidated. Autoimmune response has been recognized to be responsible only of a small minority of diabetes. The increasing trend in the worldwide prevalence of diabetes and the risk factors for both diseases are reviewed, the independent mediation for CHD of (central) adiposity in both diseases and the 'hypertriglyceridemic waist' phenotype are outlined. Evidence is described that serum lipoprotein (Lp)(a) concentrations, not only in excess, but also in apparently 'reduced' levels, as a result of autoimmune response, underlie both disorders and are closely related to insulin resistance.

Hyperglycemia and chronic liver diseases on risk of hepatocellular carcinoma in Chinese patients with type 2 diabetes--National cohort of Taiwan Diabetes Study

This study examined whether glycated hemoglobin A1C (HbA1C) and chronic liver diseases are associated with hepatocellular carcinoma (HCC) risk in Type 2 diabetic patients. A retrospective cohort study consisting of 51,705 patients with Type 2 diabetes aged 30 and over enrolled in the National Diabetes Care Management Program before 2004 was used in Cox proportional hazards models. HbA1C was independently associated with HCC incidence, and multivariate-adjusted hazard ratio (HR) of HCC was 1.20 (95% confidence interval, CI: 1.02-1.41) for patients with a level of HbA1c ≥ 9% compared with patients with a level of HbA1c <7% after multivariate adjustment. We observed a significant linear trend in HCC incidence with increasing HbA1c (p for trend = 0.02, HR = 1.07, 95% CI = 1.01-1.12 for every 1% increment in HbA1c). We observed significant HRs of HCC for patients with a level of HbA1c ≥ 9% with alcoholic liver damage, liver cirrhosis, HBV, HCV and any one of chronic liver diseases compared with patients with a level of HbA1c <9% and no counterpart comorbidity in the entire sample (HR = 8.63, 95% CI = 1.41-52.68; HR = 5.02, 95% CI = 3.10-8.12; HR = 2.53, 95% CI = 1.10-5.85; HR = 1.79, 95% CI = 1.01-3.17; and HR = 3.59, 95% CI = 2.56-5.02, respectively). Our results suggest significant joint associations of HbA1c ≥ 9% and chronic liver diseases. Lifestyle or treatment interventions such as maintaining a satisfactory glycemic control and chronic liver diseases may reduce the burden of HCC.

Lipid and liver abnormalities in haemoglobin A1c-defined prediabetes and type 2 diabetes

BACKGROUND AND AIMS

We aimed to investigate lipid abnormalities and liver steatosis in patients with HbA1c-defined prediabetes and type 2 diabetes compared to individuals with HbA1c-defined normoglycaemia.

METHODS AND RESULTS

Ninety-one subjects with prediabetes according to HbA1c, i.e. from 5.7 to 6.4% (39-46 mmol/mol), 50 newly diagnosed patients with HbA1c-defined type 2 diabetes (HbA1c ≥6.5% [≥48 mmol/mol]), and 67 controls with HbA1c lower than 5.7% (<39 mmol/mol), were studied. Fasting blood samples for lipid profiles, fatty liver index (FLI), bioimpedance analysis, ultrasound scan of the liver, and BARD (body mass index, aspartate aminotransferase/alanine aminotransferase ratio, diabetes) score for evaluation of liver fibrosis, were performed in all subjects. In comparison to controls, subjects with prediabetes were characterised by: lower apolipoprotein AI and HDL cholesterol levels, higher blood pressure, triglycerides levels and apolipoprotein B/apolipoprotein AI ratio, higher FLI, increased prevalence of and more severe hepatic steatosis, similar BARD score, and higher total body fat mass. In comparison to subjects with diabetes, subjects with prediabetes exhibited: similar blood pressure and apolipoprotein B/apolipoprotein AI ratio, similar FLI, reduced prevalence of and less severe hepatic steatosis, lower BARD score, increased percent fat and lower total body muscle mass. In comparison to controls, subjects with diabetes showed: lower apolipoprotein AI and HDL cholesterol levels, higher blood pressure and triglycerides levels, higher FLI, increased prevalence of and more severe hepatic steatosis, higher BARD score, and higher total body muscle mass. Moreover, HbA1c was correlated with BMI, HOMA-IR, triglycerides, HDL cholesterol, AST, and ALT.

CONCLUSIONS

Subjects with HbA1c-defined prediabetes and type 2 diabetes, respectively, are characterised by abnormalities in lipid profile and liver steatosis, thus exhibiting a severe risk profile for cardiovascular and liver diseases.

Glycated hemoglobin measurement and prediction of cardiovascular disease

IMPORTANCE

The value of measuring levels of glycated hemoglobin (HbA1c) for the prediction of first cardiovascular events is uncertain.

OBJECTIVE

To determine whether adding information on HbA1c values to conventional cardiovascular risk factors is associated with improvement in prediction of cardiovascular disease (CVD) risk.

DESIGN, SETTING, AND PARTICIPANTS

Analysis of individual-participant data available from 73 prospective studies involving 294,998 participants without a known history of diabetes mellitus or CVD at the baseline assessment.

MAIN OUTCOMES AND MEASURES

Measures of risk discrimination for CVD outcomes (eg, C-index) and reclassification (eg, net reclassification improvement) of participants across predicted 10-year risk categories of low (<5%), intermediate (5% to <7.5%), and high (≥ 7.5%) risk.

RESULTS

During a median follow-up of 9.9 (interquartile range, 7.6-13.2) years, 20,840 incident fatal and nonfatal CVD outcomes (13,237 coronary heart disease and 7603 stroke outcomes) were recorded. In analyses adjusted for several conventional cardiovascular risk factors, there was an approximately J-shaped association between HbA1c values and CVD risk. The association between HbA1c values and CVD risk changed only slightly after adjustment for total cholesterol and triglyceride concentrations or estimated glomerular filtration rate, but this association attenuated somewhat after adjustment for concentrations of high-density lipoprotein cholesterol and C-reactive protein. The C-index for a CVD risk prediction model containing conventional cardiovascular risk factors alone was 0.7434 (95% CI, 0.7350 to 0.7517). The addition of information on HbA1c was associated with a C-index change of 0.0018 (0.0003 to 0.0033) and a net reclassification improvement of 0.42 (-0.63 to 1.48) for the categories of predicted 10-year CVD risk. The improvement provided by HbA1c assessment in prediction of CVD risk was equal to or better than estimated improvements for measurement of fasting, random, or postload plasma glucose levels.

CONCLUSIONS AND RELEVANCE

In a study of individuals without known CVD or diabetes, additional assessment of HbA1c values in the context of CVD risk assessment provided little incremental benefit for prediction of CVD risk.

Low hemoglobin A(1c) in nondiabetic adults: an elevated risk state?

OBJECTIVE

To identify predictors of low hemoglobin A(1c) (HbA(1c)) (<5.0%) and to investigate the association of low HbA(1c) with cause-specific mortality and risk of liver disease hospitalization.

RESEARCH DESIGN AND METHODS

Prospective cohort study of 13,288 participants in the Atherosclerosis Risk in Communities Study. Logistic regression was used to identify cross-sectional correlates of low HbA(1c), and Cox proportional hazards models were used to estimate the association of low HbA(1c) with cause-specific mortality.

RESULTS

Compared with participants with HbA(1c) in the normal range (5.0 to <5.7%), participants with low HbA(1c) were younger, less likely to smoke, had lower BMI, lower white cell count and fibrinogen levels, and lower prevalence of hypercholesterolemia and history of coronary heart disease. However, this group was more likely to have anemia and had a higher mean corpuscular volume. In adjusted Cox models with HbA(1c) of 5.0 to <5.7% as the reference group, HbA(1c) <5.0% was associated with a significantly increased risk of all-cause mortality (hazard ratio [HR]: 1.32, 95% CI: 1.13-1.55) and of cancer death (1.47, 95% CI: 1.16-1.84). We also noted nonsignificant trends toward increased risk of death from cardiovascular causes (1.27, 95% CI: 0.93-1.75) and respiratory causes (1.42, 95% CI: 0.78-2.56). There was a J-shaped association between HbA(1c) and risk of liver disease hospitalization.

CONCLUSIONS

No single cause of death appeared to drive the association between low HbA(1c) and total mortality. These results add to evidence that low HbA(1c) values may be a generalized marker of mortality risk in the general population.