The impact of glycated hemoglobin on risk of hypertension: a Mendelian randomization study using UK Biobank

The synergistic effect of triglyceride-glucose index and HbA1c on blood pressure control in patients with hypertension: a retrospective cohort study

Triglyceride-Glucose Index (TyG index) and HbA1c are metabolic risk factors associated with insulin resistance (IR), which have been confirmed to be independently correlated with the incidence of hypertension. However, there is limited research specifically focusing on the interaction between these two metabolic risk factors in hypertensive populations. Currently, it remains unclear how the metabolic indicators TyG index and HbA1c affect BP control in individuals with hypertension. This study aims to investigate the value and interaction of TyG index and HbA1c in blood pressure (BP) control among hypertensive patients. The results are conducive to enhancing the effectiveness of clinical BP control for individuals with hypertension. This cohort study included 99,336 adults diagnosed with hypertension. Participants were grouped according to the median of TyG index and HbA1c. The main endpoint is inadequate BP control. Multivariable-adjusted risk ratios and multivariable Cox regression analysis were used to represent the relationship between BP control levels and metabolic risk factors. Finally, we evaluated the interaction between TyG index and HbA1c in the population with inadequate BP control. This study confirmed that TyG index and HbA1c, as metabolic risk factors, are independently associated with poor BP control (P < 0.05). In multivariable Cox regression analysis, it was found that TyG index and HbA1c were significantly associated with poor BP control. In the male elderly population, HbA1c was significantly associated with poor BP control (P = 0.029).

A Guide for Selection of Genetic Instruments in Mendelian Randomization Studies of Type 2 Diabetes and HbA1c: Toward an Integrated Approach

In this study we examine the instrument selection strategies currently used throughout the type 2 diabetes and HbA1c Mendelian randomization (MR) literature. We then argue for a more integrated and thorough approach, providing a framework to do this in the context of HbA1c and diabetes. We conducted a literature search for MR studies that have instrumented diabetes and/or HbA1c. We also used data from the UK Biobank (UKB) (N = 349,326) to calculate instrument strength metrics that are key in MR studies (the F statistic for average strength and R2 for total strength) with two different methods ("individual-level data regression" and Cragg-Donald formula). We used a 157-single nucleotide polymorphism (SNP) instrument for diabetes and a 51-SNP instrument (with partition into glycemic and erythrocytic as well) for HbA1c. Our literature search yielded 48 studies for diabetes and 22 for HbA1c. Our UKB empirical examples showed that irrespective of the method used to calculate metrics of strength and whether the instrument was the main one or included partition by function, the HbA1c genetic instrument is strong in terms of both average and total strength. For diabetes, a 157-SNP instrument was shown to have good average strength and total strength, but these were both substantially lesser than those of the HbA1c instrument. We provide a careful set of five recommendations to researchers who wish to genetically instrument type 2 diabetes and/or HbA1c. In MR studies of glycemia, investigators should take a more integrated approach when selecting genetic instruments, and we give specific guidance on how to do this.

Association of hemoglobin A1c with the incidence of hypertension: A large prospective study

Background

Although hemoglobin A1c (HbA1c) is closely related to diabetes, its relationship with the incidence of hypertension is still unknown, so we aimed to evaluate the relationship between HbA1c and the incidence of hypertension in the general population.

Method

In this large prospective cohort study with a median follow-up of 2 years, we included 4,074 participants from the China Health and Nutrition Survey (CHNS). Multivariate COX regression, subgroup analysis, receiver operator characteristic (ROC) curve and restricted cubic spline (RCS) were used to evaluate the relationship between HbA1c and incidental hypertension.

Results

Compared with participants without incident hypertension, participants with incident hypertension had higher levels of HbA1c (P < 0.05). In univariate COX regression analysis, HbA1c was associated with the risk of hypertension (HR: 1.161, 95% CI: 1.105-1.221, P < 0.001). In multivariate COX regression analysis adjusted for confounding variables, HbA1c was still closely related to the risk of hypertension (HR: 1.102, 95% CI: 1.006-1.206, P = 0.037). And subgroup analysis showed that the relationship between HbA1c and hypertension remained significant in female, lower than high school and non-obese subgroups (P < 0.05). ROC curve also showed that HbA1c could predict the risk of hypertension (AUC = 0.583, 95% CI: 0.568-0.598, P < 0.001). Further RCS analysis showed that HbA1c was positively correlated with the risk of hypertension (P for nonlinearity = 0.642).

Conclusion

HbA1c was linearly and positively associated with the incidence of hypertension.

Differentiating Associations of Glycemic Traits With Atherosclerotic and Thrombotic Outcomes: Mendelian Randomization Investigation

We conducted a Mendelian randomization analysis to differentiate associations of four glycemic indicators with a broad range of atherosclerotic and thrombotic diseases. Independent genetic variants associated with fasting glucose (FG), 2 h glucose after an oral glucose challenge (2hGlu), fasting insulin (FI), and glycated hemoglobin (HbA1c) at the genome-wide significance threshold were used as instrumental variables. Summary-level data for 12 atherosclerotic and 4 thrombotic outcomes were obtained from large genetic consortia and the FinnGen and UK Biobank studies. Higher levels of genetically predicted glycemic traits were consistently associated with increased risk of coronary atherosclerosis-related diseases and symptoms. Genetically predicted glycemic traits except HbA1c showed positive associations with peripheral artery disease risk. Genetically predicted FI levels were positively associated with risk of ischemic stroke and chronic kidney disease. Genetically predicted FG and 2hGlu were positively associated with risk of large artery stroke. Genetically predicted 2hGlu levels showed positive associations with risk of small vessel stroke. Higher levels of genetically predicted glycemic traits were not associated with increased risk of thrombotic outcomes. Most associations for genetically predicted levels of 2hGlu and FI remained after adjustment for other glycemic traits. Increase in glycemic status appears to increase risks of coronary and peripheral artery atherosclerosis but not thrombosis.

The association between glycosylated haemoglobin and newly diagnosed hypertension in a non-diabetic Sudanese population: a cross-sectional study

BACKGROUND

Glycosylated haemoglobin (HbA1c) is considered reliable for diagnosing and monitoring diabetes mellitus (DM). It also indicates cardiovascular complications related to DM. However, only a few studies have been conducted on this topic.

METHODS

We conducted a cross-sectional study to investigate the association between newly diagnosed hypertension and HbA1c among non-diabetic Sudanese adults. The sociodemographic characteristics of the participants in the sample were gathered using a questionnaire, and HbA1c was measured using an Ichroma machine.

RESULTS

Three hundred and eighty-four healthy participants were enrolled in this study. The median (interquartile range [IQR]) age was 56.0 (14.0) years, and 72.1% of the participants were female. The median (IQR) body mass index (BMI) was 31.2 (8.7) kg/m². One hundred and fifteen (29.9%) participants presented newly diagnosed hypertension. The results of the multivariate analysis showed that age (adjusted odd ratio [AOR] = 1.03; 95% confidence interval [CI] = 1.01‒1.05); BMI (AOR = 1.09; 95% CI = 1.05‒1.14); HbA1c levels (AOR = 2.18; 95% CI = 1.29‒3.67) was positively associated with newly diagnosed hypertension. For an HbA1c level of 5.0% or more, the sensitivity and specificity of newly diagnosed hypertension were 91.3% and 28.2%, respectively (area under the curve = 0.61; 95% CI = 0.55-0.67; P ˂ 0.001). Participants who presented HbA1c levels of 5.0% or more were found to be at higher risk for newly diagnosed hypertension (AOR = 2.53; 95% CI = 1.14‒5.61).

CONCLUSION

The results of this study indicated a high prevalence of newly diagnosed hypertension, and HbA1c levels were positively associated with newly diagnosed hypertension.

Assessing the linear and non-linear association of HbA1c with cardiovascular disease: a Mendelian randomisation study

AIMS/HYPOTHESIS

We aimed to evaluate whether genetically predicted HbA_1c has an effect on the risk of cardiovascular diseases and investigate the shape of the relationship of genetically predicted HbA_1c with cardiovascular diseases.

METHODS

We performed linear univariable, multivariable and non-linear Mendelian randomisation analyses in 373,571 white British participants (mean age 56.9) from the UK Biobank.

RESULTS

In univariable linear Mendelian randomisation analysis, a 1 mmol/mol increase in genetically predicted HbA_1c was associated with higher risk of coronary artery disease (OR 1.03, 95% CI 1.02, 1.05), stroke (OR 1.02, 95% CI 1.00, 1.05) and hypertension (OR 1.02, 95% CI 1.01, 1.03). Multivariable Mendelian randomisation adjusted for the effect of haemoglobin gave a consistent conclusion for coronary artery disease. The associations with stroke and hypertension were directionally similar but with wider CI overlapping the null. Non-linear Mendelian randomisation indicated that the shape of the effect of genetically predicted HbA_1c on cardiovascular outcomes was likely linear.

CONCLUSIONS/INTERPRETATION

The study suggests a detrimental effect of HbA_1c on coronary artery disease in both men and women, and the effect is via a glycaemic characteristic. The shape of the genetic association of HbA_1c with these cardiovascular outcomes, in particular coronary artery disease, is likely to be linear.

Fasting Blood Glucose and 2-h Postprandial Blood Glucose Predict Hypertension: A Report from the REACTION Study

INTRODUCTION

Although diabetes is associated with hypertension, whether high blood glucose levels promote hypertension remains controversial. In this study we compared the predictive power of fasting plasma glucose (FPG), 2-h postprandial blood glucose (2hPG), and glycated hemoglobin (HbA1c) for the development of hypertension.

METHODS

This study was a substudy of the REACTION study, an ongoing longitudinal cohort study investigating the relationship of prediabetes and type 2 diabetes with the risk of cancer in an urban Northern Chinese population in Beijing. Logistic regression analysis was used to calculate odds ratios (ORs) after adjustment for risk factors for hypertension, including age, sex, body mass index, and triglycerides.

RESULTS

Among the 3437 participants, 497 developed hypertension during the 4-year follow-up. The logistic regression analysis showed that elevated FPG and 2hPG levels (FPG: OR 1.529; 95% confidence interval [CI] 1.348-1.735; 2hPG: OR 1.144; 95% CI 1.100-1.191), but not HbA1c, were independent risk factors for the development of hypertension. In the highest quartile of FPG and 2hPG levels, the multivariable-corrected ORs were 2.115 (95% CI 1.612-2.777) and 2.346 (95% CI 1.787-3.080), respectively, compared with the lowest quartile. The adjusted models showed no significant correlations between quartile HbA1c levels and the development of hypertension.

CONCLUSION

Higher FPG and 2hPG levels, but not HbA1c levels, are independent risk factors for developing hypertension in an urban Northern Chinese population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01206869.

An Academic Clinician's Road Map to Hypertension Genomics: Recent Advances and Future Directions MMXX

At the dawn of the new decade, it is judicious to reflect on the boom of knowledge about polygenic risk for essential hypertension supplied by the wealth of genome-wide association studies. Hypertension continues to account for significant cardiovascular morbidity and mortality, with increasing prevalence anticipated. Here, we overview recent advances in the use of big data to understand polygenic hypertension, as well as opportunities for future innovation to translate this windfall of knowledge into clinical benefit.

Impact of glycemic traits, type 2 diabetes and metformin use on breast and prostate cancer risk: a Mendelian randomization study

Objectives

Observational studies suggest glycemic traits and type 2 diabetes are positively associated, and metformin inversely associated with breast and prostate cancer risk. However, observational studies are susceptible to unmeasured confounding while studies of metformin use are also vulnerable to immortal time bias. The use of Mendelian randomization may reduce confounding due to random allocation of relevant genetic markers at birth, and may reduce immortal time bias (for metformin-related variants analysis) since the start of exposure is at birth.

Research design and methods

We identified strong genetic predictors of fasting glucose, glycated hemoglobin, and type 2 diabetes from the Meta-Analyses of Glucose and Insulin-related traits Consortium and Diabetes Genetics Replication And Meta-analysis Consortium (n=140 595 for glucose; n=123 665 for HbA1c; n=898 130 for type 2 diabetes) and of AMPK-instrumented HbA1c reduction as a proxy of metformin and applied them to large genome-wide association studies of breast cancer (Breast Cancer Association Consortium; BCAC) and prostate cancer (Prostate Cancer Association Group to Investigate Cancer-Associated Alterations in the Genome; PRACTICAL). We used inverse variance weighting to obtain estimates. Sensitivity analyses included use of MR-Egger, weighted median, exclusion of pleiotropic instruments, and validation using UK Biobank (breast cancer only).

Results

There was no association of fasting glucose (OR 1.03 per mmol/L, 95% CI 0.85 to 1.25), HbA1c (OR 1.02 per %, 95% CI 0.73 to 1.45), or type 2 diabetes (OR 0.98 per log odds, 95% CI 0.95 to 1.01) with breast cancer in BCAC, with similar findings from UK Biobank. There was no association of fasting glucose (OR 0.93 per mmol/L, 95% CI 0.73 to 1.17), HbA1c (OR 0.90 per %, 95% CI 0.58 to 1.40) or type 2 diabetes (OR 1.02 per log odds, 95% CI 0.97 to 1.07) with prostate cancer in PRACTICAL. No strong evidence was observed for AMPK-instrumented HbA1c reduction on cancer risk.

Conclusion

Glycemic traits and type 2 diabetes unlikely cause breast and prostate cancer. Whether metformin can be repurposed for cancer prevention remains unclear.