HbA1c and Risks of All-Cause and Cause-Specific Death in Subjects without Known Diabetes: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Prediabetes as a risk factor for all-cause and cause-specific mortality: a prospective analysis of 115,919 adults without diabetes in Mexico City

BACKGROUND

Prediabetes has been associated with increased all-cause and cardiovascular mortality. However, no large-scale studies have been conducted in Mexico or Latin America examining these associations.

METHODS

We analyzed data from 115,919 adults without diabetes (diagnosed or undiagnosed) aged 35-84 years who participated in the Mexico City Prospective Study between 1998 and 2004. Participants were followed until January 1st, 2021 for cause-specific mortality. We defined prediabetes according to the American Diabetes Association (ADA, HbA1c 5.7% to 6.4%) and the International Expert Committee (IEC, HbA1c 6.0-6.4%) definitions. Cox regression adjusted for confounders was used to estimate all-cause and cause-specific mortality rate ratios (RR) at ages 35-74 years associated with prediabetes.

FINDINGS

During 2,085,392 person-years of follow-up (median in survivors 19 years), there were 6,810 deaths at ages 35-74, including 1,742 from cardiovascular disease, 892 from renal disease and 108 from acute diabetic crises. Of 110,405 participants aged 35-74 years at recruitment, 28,852 (26%) had ADA-defined prediabetes and 7,203 (7%) had IEC-defined prediabetes. Compared with those without prediabetes, individuals with prediabetes had higher risk of all-cause mortality at ages 35-74 years (RR 1.13, 95% CI 1.07-1.19 for ADA-defined prediabetes and RR 1.28, 1.18-1.39 for IEC-defined prediabetes), as well as increased risk of cardiovascular mortality (RR 1.22 [1.10-1.35] and 1.42 [1.22-1.65], respectively), renal mortality (RR 1.35 [1.08-1.68] and 1.69 [1.24-2.31], respectively), and death from an acute diabetic crisis (RR 2.63 [1.76-3.94] and 3.43 [2.09-5.62], respectively). RRs were larger at younger than at older ages, and similar for men compared to women. The absolute excess risk associated with ADA and IEC-defined prediabetes at ages 35-74 accounted for6% and 3% of cardiovascular deaths respectively, 10% and 5% of renal deaths respectively, and 31% and 14% of acute diabetic deaths respectively.

INTERPRETATION

Prediabetes is a significant risk factor for all-cause, cardiovascular, renal, and acute diabetic deaths in Mexican adults. Identification and timely management of individuals with prediabetes for targeted risk reduction could contribute to reducing premature mortality from cardiometabolic causes in this population.

FUNDING

Wellcome Trust, the Mexican Health Ministry, the National Council of Science and Technology for Mexico, Cancer Research UK, British Heart Foundation, UK Medical Research Council. Instituto Nacional de Geriatría (Mexico City).

Outcomes of Prediabetes Compared with Normoglycaemia and Diabetes Mellitus in Patients Undergoing Percutaneous Coronary Intervention: A Systematic Review and Meta-analysis

Background: Patients with prediabetes are at increased risk of coronary artery disease (CAD). However, the association between prediabetes and adverse clinical outcomes following percutaneous coronary intervention (PCI) is inconsistent, in contrast to outcomes in patients with diabetes mellitus (DM). Thus, this meta-analysis evaluated the impact of dysglycaemia on PCI outcomes. Methods: The PubMed, Embase, Cochrane, and ClinicalTrials.gov databases were systematically reviewed from inception of databases until June 2022. In 17 studies, outcomes of PCI in patients with prediabetes were compared with patients who were normoglycaemic, and patients with DM. The primary outcome was all-cause mortality at the longest follow-up. Results: Included were 12 prospective and five retrospective studies, with 11,868, 14,894 and 13,536 patients undergoing PCI in the prediabetes, normoglycaemic and DM groups, respectively. Normoglycaemic patients had a statistically lower risk of all-cause mortality, (risk ratio [RR] 0.66, 95% confidence interval [CI] 0.52-0.84), myocardial infarction (MI; RR 0.76, 95% CI 0.61-0.95) and cardiac mortality (RR 0.58, 95% CI 0.39-0.87) compared with prediabetic patients undergoing PCI at the longest follow-up. Patients with prediabetes had a lower risk of all-cause mortality (RR=0.72 [95% CI 0.53-0.97]) and cardiac mortality (RR =0.47 [95% CI 0.23-0.93]) compared with patients with DM who underwent PCI. Conclusion: Among patients who underwent PCI for CAD, the risk of all-cause and cardiac mortality, major adverse cardiovascular events and MI in prediabetic patients was higher compared with normoglycaemic patients but lower compared with patients with DM.

The association between hemoglobin A1c and all-cause mortality in the ICU: A cross-section study based on MIMIC-IV 2.0

BACKGROUND

Hyperglycemia has been reported to be associated with the outcomes of patients in the intensive care unit (ICU). However, the relationship between hemoglobin A1c (HbA1c) and long-term or short-term mortality in the ICU is still unknown. This study used the Medical Information Mart for Intensive Care (MIMIC)-IV database to investigate the relationship between HbA1c and long-term or short-term mortality among ICU patients without a diabetes diagnosis.

METHODS

A total of 3,154 critically ill patients without a diabetes diagnosis who had HbA1c measurements were extracted and analyzed from the MIMIC-IV. The primary outcome was 1-year mortality, while the secondary outcomes were 30-day mortality and 90-day mortality after ICU discharge. HbA1c levels were classified into four levels according to three HbA1c values (5.0%, 5.7%, and 6.5%). The Cox regression model was used to investigate the relationship between the highest HbA1c measurement and mortality. Finally, this correlation was validated using the XGBoost machine learning model and Cox regression after propensity score matching (PSM).

RESULTS

The study eventually included 3,154 critically ill patients without diabetes who had HbA1c measurements in the database. HbA1c levels of below 5.0% or above 6.5% were significantly associated with 1-year mortality after adjusting for covariates in Cox regression (HR: 1.37; 95% CI: 1.02-1.84 or HR: 1.62; 95% CI: 1.20-2.18). In addition, HbA1c 6.5% was linked to 30-day mortality (HR: 1.81; 95% CI: 1.21-2.71) and 90-day mortality (HR: 1.62; 95% CI: 1.14-2.29). The restricted cubic spline demonstrated a U-shaped relationship between HbA1c levels and 1-year mortality. The AUCs of the training and testing datasets in the XGBoost model were 0.928 and 0.826, respectively, while the SHAP plot revealed that HbA1c was somewhat important for the 1-year mortality. Higher HbA1c levels in Cox regression were still significantly associated with 1-year mortality after PSM for other factors.

CONCLUSIONS

The 1-year mortality, 30-day mortality, and 90-day mortality rates for critically ill patients after discharge from ICU are significantly associated with HbA1c. HbA1c < 5.0% and ≥6.5% would increase 30-day, 90-day, and 1-year mortality, while levels between 5.0% and 6.5% of HbA1c did not significantly affect these outcomes.

Unraveling female reproductive senescence to enhance healthy longevity

In a society where women often want successful careers and equal opportunities to men, the early nature of ovarian aging often forces women to make difficult life choices between career and family development. Fertility in women begins to decline after the age of 37 years and it is rare for pregnancies to occur after 45. This reproductive decline in women is inevitable and culminates in menopause, which is a major driver of age-related diseases. In a world where biomedical advances are leading to modifiable biological outcomes, it is time to focus on mitigating female reproductive senescence to maintain fertility and preserve age-related hormonal functions, with the goal of providing increased life choices and enhancing healthspan. To date, reproductive longevity research remains an understudied field. More needs to be done to unravel the biology of the ovarian follicles, which are the functional units of reproductive lifespan and are comprised of cell types including the oocyte (female gamete) and a group of specialized supporting somatic cells. Biological attempts to maintain the quality and quantity of follicles in animal models through manipulating pathways involved in aging can potentially prolong female reproductive lifespan and healthspan. Here, we summarize the molecular events driving ovarian aging and menopause and the interventional strategies to offset these events. Developing solutions to female reproductive senescence will open doors to discover ways to enhance true healthy longevity for both men and women.

Effects of recreational sports and combined training on blood pressure and glycated hemoglobin in middle-aged and older adults: A systematic review with meta-analysis

BACKGROUND

Combined resistance and aerobic training (CT) is the most suitable form of exercise training to simultaneously improve strength and cardiometabolic profile in middle-aged and older adults. Recreational sports (RS) emerge as an alternative to CT to improve these outcomes. We performed a meta-analysis on the effects of RS and CT on systolic blood pressure (SBP), diastolic blood pressure (DBP) and glycated hemoglobin (HbA1c) in middle-aged and older adults and to compare these exercise interventions to a non-exercising control group (CON).

METHODS

Search was conducted using the databases at PubMed, COCHRANE and SciELO between July and August 2020. Studies that included men and women aged ≥45 years, healthy or with values for SBP ≥130 mmHg or DBP ≥80 mmHg or with type 2 diabetes and performed RS or CT versus CON.

RESULTS

From 6017 records, 27 studies were included (9 RS and 18 CT). The analysis included 1411 participants with 55 ± 8 years. RS and CT were associated with reductions in SBP (RS: -7.2 mmHg, P = 0.03; CT: -3.6 mmHg, P < 0.001) and DBP (RS: -3.6 mmHg, P = 0.02; CT: -3.1 mmHg, P < 0.001) versus CON. Only CT was associated with a reduction in HbA1c versus CON (-0.47%; P < 0.001).

CONCLUSIONS

RS and CT are effective exercise interventions to improve BP in middle-aged and older adults. CT seems to be an excellent strategy to reduce HbA1c, and future studies are necessary to confirm the effectiveness of RS to improve HbA1c.

The U-Shape Relationship Between Glycated Hemoglobin Level and Long-Term All-Cause Mortality Among Patients With Coronary Artery Disease

Background: Although glycated hemoglobin (HbA1c) was considered as a prognostic factor in some subgroup of coronary artery disease (CAD), the specific relationship between HbA1c and the long-term all-cause death remains controversial in patients with CAD.

Methods: The study enrolled 37,596 CAD patients and measured HbAlc at admission in Guangdong Provincial People's Hospital. The patients were divided into 4 groups according to HbAlc level (Quartile 1: HbA1c ≤ 5.7%; Quartile 2: 5.7% < HbA1c ≤ 6.1%; Quartile 3: 6.1% < HbA1c ≤ 6.7%; Quartile 4: HbA1c > 6.7%). The study endpoint was all-cause death. The restricted cubic splines and cox proportional hazards models were used to investigate the association between baseline HbAlc levels and long-term all-cause mortality.

Results: The median follow-up was 4 years. The cox proportional hazards models revealed that HbAlc is an independent risk factor in the long-term all-cause mortality. We also found an approximate U-shape association between HbA1c and the risk of mortality, including increased risk of mortality when HbA1c ≤ 5.7% and HbA1c > 6.7% [Compared with Quartile 2, Quartile 1 (HbA1c ≤ 5.7), aHR = 1.13, 95% CI:1.01–1.26, P < 0.05; Quartile 3 (6.1% < HbA1c ≤ 6.7%), aHR = 1.04, 95% CI:0.93–1.17, P =0.49; Quartile 4 (HbA1c > 6.7%), aHR = 1.32, 95% CI:1.19–1.47, P < 0.05].

Conclusions: Our study indicated a U-shape relationship between HbA1c and long-term all-cause mortality in CAD patients.

Mapping intersectional inequalities in biomarkers of healthy ageing and chronic disease in older English adults

Chronic diseases and their inequalities amongst older adults are a significant public health challenge. Prevention and treatment of chronic diseases will benefit from insight into which population groups show greatest risk. Biomarkers are indicators of the biological mechanisms underlying health and disease. We analysed disparities in a common set of biomarkers at the population level using English national data (n = 16,437). Blood-based biomarkers were HbA1c, total cholesterol and C-reactive protein. Non-blood biomarkers were systolic blood pressure, resting heart rate and body mass index. We employed an intersectionality perspective which is concerned with how socioeconomic, gender and ethnic disparities combine to lead to varied health outcomes. We find granular intersectional disparities, which vary by biomarker, with total cholesterol and HbA1c showing the greatest intersectional variation. These disparities were additive rather than multiplicative. Each intersectional subgroup has its own profile of biomarkers. Whilst the majority of variation in biomarkers is at the individual rather than intersectional level (i.e. intersections exhibit high heterogeneity), the average differences are potentially associated with important clinical outcomes. An intersectional perspective helps to shed light on how socio-demographic factors combine to result in differential risk for disease or potential for healthy ageing.

Burden of disease and costs associated with type 2 diabetes in emerging and established markets: systematic review analyses

Objectives: To estimate the clinical and economic burden of type 2 diabetes (T2D) in established (EST) and emerging markets (EMG).Methods: Three systematic literature reviews were conducted in MEDLINE and Embase to capture all relevant publications reporting 1) the epidemiology of T2D and complications in T2D and 2) the economic burden of T2D and associated complications.Results: In total, 294 studies were included in this analysis. Evidence indicates a high and increasing overall prevalence of T2D globally, ranging up to 23% in EMG markets and 14% in EST markets. Undiagnosed cases were higher in EMG versus EST markets (up to 67% vs 38%), potentially due to a lack of education and disease awareness in certain regions, that could lead to important clinical and economic consequences. Poor glycemic control was associated with the development of several complications (e.g. retinopathy, cardiovascular diseases and nephropathy) that increase the risk of morbidity and mortality. Direct costs were up to 9-fold higher in patients with vs without T2D-related complications.Conclusions: The burden of T2D, related complications and inherent costs are higher in emerging versus established market countries. This review explores potential strategies to reduce costs and enhance outcomes of T2D treatment in developing countries.

Ambient air pollution exposure association with diabetes prevalence and glycosylated hemoglobin (HbA1c) levels in China. Cross-sectional analysis from the WHO study of AGEing and adult health wave 1

Over the past decades, air pollution has become one of the critical environmental health issues in China. The present study aimed to evaluate links between ambient air pollution and the prevalence of type 2 diabetes mellitus (T2DM) and the levels of glycosylated hemoglobin (HbA1c). A multilevel linear and logistic regression was used to assess these associations among 7,770 participants aged ≥50 years from the WHO Study on global AGEing and adult health (SAGE) in China in 2007-2010. The average exposure to each of pollutants (particulate matter with an aerodynamic diameter of ≤10 μm/≤2.5 μm/≤1 μm [PM₁₀/PM_2.5/PM₁] and nitrogen dioxide [NO₂]) was estimated using a satellite-based spatial statistical model. In logistic models, a 10 µg/m³ increase in PM₁₀ and PM_2.5 was associated with increased T2DM prevalence (Prevalence Odds Ratio, POR: 1.27; 95% CI: 1.11, 1.45 and POR: 1.23; 95% CI: 1.03, 1.46). Similar increments in PM₁₀, PM_2.5, PM₁ and NO₂ were associated with increase in HbA1c levels of 1.8% (95% CI: 1.3, 2.3), 1.3% (95% CI: 1.1, 1.5), 0.7% (95% CI: 0.1, 1.3), and 0.8% (95% CI: 0.4, 1.2), respectively. In a large cohort of older Chinese adults, air pollution was liked to both higher T2DM prevalence and elevated HbA1c levels.

A Translational In Vivo and In Vitro Metabolomic Study Reveals Altered Metabolic Pathways in Red Blood Cells of Type 2 Diabetes

Clinical parameters used in type 2 diabetes mellitus (T2D) diagnosis and monitoring such as glycosylated haemoglobin (HbA1c) are often unable to capture important information related to diabetic control and chronic complications. In order to search for additional biomarkers, we performed a pilot study comparing T2D patients with healthy controls matched by age, gender, and weight. By using ¹H-nuclear magnetic resonance (NMR) based metabolomics profiling of red blood cells (RBCs), we found that the metabolic signature of RBCs in T2D subjects differed significantly from non-diabetic controls. Affected metabolites included glutathione, 2,3-bisphophoglycerate, inosinic acid, lactate, 6-phosphogluconate, creatine and adenosine triphosphate (ATP) and several amino acids such as leucine, glycine, alanine, lysine, aspartate, phenylalanine and tyrosine. These results were validated by an independent cohort of T2D and control patients. An analysis of the pathways in which these metabolites were involved showed that energetic and redox metabolism in RBCs were altered in T2D, as well as metabolites transported by RBCs. Taken together, our results revealed that the metabolic profile of RBCs can discriminate healthy controls from T2D patients. Further research is needed to determine whether metabolic fingerprint in RBC could be useful to complement the information obtained from HbA1c and glycemic variability as well as its potential role in the diabetes management.

Ex ante inequality of opportunity in health, decomposition and distributional analysis of biomarkers

We use a set of biomarkers to measure inequality of opportunity (IOp) in the risk of major chronic conditions in the UK. Applying a direct ex ante IOp approach, we find that inequalities in biomarkers attributed to circumstances account for a non-trivial part of the total variation. For example, observed circumstances account for 20 % of the total inequalities in our composite measure of multi-system health risk, allostatic load. We propose an extension to the decomposition of ex ante IOp to complement the mean-based approach, analysing the contribution of circumstances across the quantiles of the biomarker distributions. Shapley decompositions show that, for most of the biomarkers, the percentage contribution of socioeconomic circumstances (education and childhood socioeconomic status), relative to differences attributable to age and gender, increase towards the right tail of the biomarker distribution, where health risks are more pronounced.

Relationship between hemoglobin A1c and serum troponin in patients with diabetes and cardiovascular events

OBJECTIVES

Diabetes mellitus is a group of metabolic disorders associated with high risk for cardiovascular disease. Although troponins are primarily clinically used for the diagnosis of acute coronary syndrome, they are also used in risk assessment in patients with acute coronary syndrome as well as in a number of other conditions. The aim of this review was to investigate the relationship between hemoglobin A1c and serum troponin in patients with diabetes and cardiovascular events.

METHODS

Hemoglobin A1c has been chosen as the best clinical indicator of glucose control and risk of micro and macrovascular complications. We investigated cardiac troponins as a group of markers of muscle injury which includes troponin T, troponin I and troponin C. Troponin T and I are specific for myocardial injury, compared to C which is specific for skeletal muscle.

RESULTS

In this review, we showed that there was a causal relation between hemoglobin A1c levels and serum troponin concentrations. Hemoglobin A1c has shown to be a positive predictive factor of incidence, mortality and morbidity of conditions such as acute coronary syndrome, arrhythmias, stroke, pulmonary embolism and other conditions that causes troponin elevation by its release in circulation.

CONCLUSIONS

Chronic hyperglycemia decreases glomerular filtration and consequently decreases troponin elimination and also by affecting the heart microcirculation it leads to microvascular damage and consequently to ischemia which contribute to troponin concentration elevation. Furthermore, correlation between hemoglobin A1c and troponin concentration manifests in their prognostic value for mortality.

Effect of a 2-hour interval between dinner and bedtime on glycated haemoglobin levels in middle-aged and elderly Japanese people: a longitudinal analysis of 3-year health check-up data

Introduction

There is a need for evidence-based measures to examine the risk factors for lifestyle-related diseases. In Japan, a 2-hour interval between dinner and sleep is recommended as a healthy practice. However, the effect of an appropriate duration between dinner and bedtime on glycated haemoglobin (HbA1c) levels remains unclear. This study aimed to identify the effect of a duration of 2 hours or shorter between dinner and bedtime on HbA1c levels in middle-aged and elderly Japanese individuals.

Methods

A longitudinal analysis of health check-up data (2012, 2013 and 2014) was performed. Lifestyle and anthropometric data of individuals aged 40–74 years who did not have any pre-diabetic and diabetic conditions were collected for multilevel analysis. Univariate analysis was performed to assess the influence of each lifestyle variable. Then, two-level random intercept models were created using statistical software SAS 9.3 (SAS Institute Inc, Cary, NC, USA).

Results

The cohort comprised 1573 individuals in 2012, two-thirds of whom were women. The mean HbA1c level was 5.20% in 2012 and 5.58% in 2013 and 2014. A total of 83 (16.1%) men and 70 (7.5%) women fell asleep within 2 hours after dinner. The influence of ensuring a 2-hour interval between dinner and bedtime did not have a remarkable effect on increasing HbA1c levels. The regression coefficient of 2-hour interval and HbA1c levels over time was −0.02 (p=0.45). Smoking (p=0.013), alcohol consumption (p=0.010) and higher body mass index (BMI) (p<0.001) may have influenced HbA1c trends.

Conclusion

Durations of 2 hours or shorter between dinner and bedtime did not influence HbA1c changes in middle-aged and elderly Japanese people. Instead, the focus should be on maintaining a normal BMI and abstaining from smoking and consuming alcohol to ensure stable HbA1c patterns in the long term.

Does intake of bread supplemented with wheat germ have a preventive role on cardiovascular disease risk markers in healthy volunteers? A randomised, controlled, crossover trial

OBJECTIVE

Intake of whole grains is associated with a reduced risk of cardiovascular disease (CVD). This evidence is also strong for bran alone, but findings about germ are conflicting. Our aim was to elucidate the role of germ in primary prevention of cardiovascular events, and therefore, a staple food was selected for 6 g of germ supplementation. This corresponds to sixfold increase in the global mean consumption of germ, while preserving the sensory proprieties of refined bread which is crucial for consumer's acceptance.

DESIGN

Randomised, double-blinded, crossover, controlled clinical trial with 15-week follow-up comprising a 2-week run-in, two intervention periods of 4 weeks each and a 5-week washout period.

SETTING

A single centre in the north of Portugal.

PARTICIPANTS

55 eligible healthy adults (mean age of 34 years and body mass index between 19 and 38 kg/m²) were randomly assigned.

INTERVENTIONS

The study consisted of two intervention periods including daily intake of refined wheat bread enriched with 6 g of wheat germ and control (non-enriched bread).

OUTCOMES

Changes in fasting cholesterol and triglycerides, fasting and postprandial glucose, insulin sensitivity and C reactive protein.

RESULTS

We observed no significant effect of daily intake of wheat germ on cholesterol and triglycerides levels, on postprandial glucose response and on insulin sensitivity. Incremental area under curve glucose and homeostasis model assessment for insulin resistance did not change, suggesting that 6 g of wheat germ have no effect on glucose metabolism. No effect was also observed in the subgroup of participants who complied with the protocol (n=47).

CONCLUSIONS

The absence of alterations on lipid and glucose profiles suggests that germ up to 6 g/day may have no preventive effect on CVD risk. However, it is important to investigate other food vehicles that can accommodate higher doses of wheat germ in future studies.

TRIAL REGISTRATION NUMBER

NCT02405507.

Development of type 2 diabetes mellitus in people with intermediate hyperglycaemia

BACKGROUND

Intermediate hyperglycaemia (IH) is characterised by one or more measurements of elevated blood glucose concentrations, such as impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and elevated glycosylated haemoglobin A1c (HbA1c). These levels are higher than normal but below the diagnostic threshold for type 2 diabetes mellitus (T2DM). The reduced threshold of 5.6 mmol/L (100 mg/dL) fasting plasma glucose (FPG) for defining IFG, introduced by the American Diabetes Association (ADA) in 2003, substantially increased the prevalence of IFG. Likewise, the lowering of the HbA1c threshold from 6.0% to 5.7% by the ADA in 2010 could potentially have significant medical, public health and socioeconomic impacts.

OBJECTIVES

To assess the overall prognosis of people with IH for developing T2DM, regression from IH to normoglycaemia and the difference in T2DM incidence in people with IH versus people with normoglycaemia.

SEARCH METHODS

We searched MEDLINE, Embase, ClincialTrials.gov and the International Clinical Trials Registry Platform (ICTRP) Search Portal up to December 2016 and updated the MEDLINE search in February 2018. We used several complementary search methods in addition to a Boolean search based on analytical text mining.

SELECTION CRITERIA

We included prospective cohort studies investigating the development of T2DM in people with IH. We used standard definitions of IH as described by the ADA or World Health Organization (WHO). We excluded intervention trials and studies on cohorts with additional comorbidities at baseline, studies with missing data on the transition from IH to T2DM, and studies where T2DM incidence was evaluated by documents or self-report only.

DATA COLLECTION AND ANALYSIS

One review author extracted study characteristics, and a second author checked the extracted data. We used a tailored version of the Quality In Prognosis Studies (QUIPS) tool for assessing risk of bias. We pooled incidence and incidence rate ratios (IRR) using a random-effects model to account for between-study heterogeneity. To meta-analyse incidence data, we used a method for pooling proportions. For hazard ratios (HR) and odds ratios (OR) of IH versus normoglycaemia, reported with 95% confidence intervals (CI), we obtained standard errors from these CIs and performed random-effects meta-analyses using the generic inverse-variance method. We used multivariable HRs and the model with the greatest number of covariates. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.

MAIN RESULTS

We included 103 prospective cohort studies. The studies mainly defined IH by IFG5.6 (FPG mmol/L 5.6 to 6.9 mmol/L or 100 mg/dL to 125 mg/dL), IFG6.1 (FPG 6.1 mmol/L to 6.9 mmol/L or 110 mg/dL to 125 mg/dL), IGT (plasma glucose 7.8 mmol/L to 11.1 mmol/L or 140 mg/dL to 199 mg/dL two hours after a 75 g glucose load on the oral glucose tolerance test, combined IFG and IGT (IFG/IGT), and elevated HbA1c (HbA1c5.7: HbA1c 5.7% to 6.4% or 39 mmol/mol to 46 mmol/mol; HbA1c6.0: HbA1c 6.0% to 6.4% or 42 mmol/mol to 46 mmol/mol). The follow-up period ranged from 1 to 24 years. Ninety-three studies evaluated the overall prognosis of people with IH measured by cumulative T2DM incidence, and 52 studies evaluated glycaemic status as a prognostic factor for T2DM by comparing a cohort with IH to a cohort with normoglycaemia. Participants were of Australian, European or North American origin in 41 studies; Latin American in 7; Asian or Middle Eastern in 50; and Islanders or American Indians in 5. Six studies included children and/or adolescents.Cumulative incidence of T2DM associated with IFG5.6, IFG6.1, IGT and the combination of IFG/IGT increased with length of follow-up. Cumulative incidence was highest with IFG/IGT, followed by IGT, IFG6.1 and IFG5.6. Limited data showed a higher T2DM incidence associated with HbA1c6.0 compared to HbA1c5.7. We rated the evidence for overall prognosis as of moderate certainty because of imprecision (wide CIs in most studies). In the 47 studies reporting restitution of normoglycaemia, regression ranged from 33% to 59% within one to five years follow-up, and from 17% to 42% for 6 to 11 years of follow-up (moderate-certainty evidence).Studies evaluating the prognostic effect of IH versus normoglycaemia reported different effect measures (HRs, IRRs and ORs). Overall, the effect measures all indicated an elevated risk of T2DM at 1 to 24 years of follow-up. Taking into account the long-term follow-up of cohort studies, estimation of HRs for time-dependent events like T2DM incidence appeared most reliable. The pooled HR and the number of studies and participants for different IH definitions as compared to normoglycaemia were: IFG5.6: HR 4.32 (95% CI 2.61 to 7.12), 8 studies, 9017 participants; IFG6.1: HR 5.47 (95% CI 3.50 to 8.54), 9 studies, 2818 participants; IGT: HR 3.61 (95% CI 2.31 to 5.64), 5 studies, 4010 participants; IFG and IGT: HR 6.90 (95% CI 4.15 to 11.45), 5 studies, 1038 participants; HbA1c5.7: HR 5.55 (95% CI 2.77 to 11.12), 4 studies, 5223 participants; HbA1c6.0: HR 10.10 (95% CI 3.59 to 28.43), 6 studies, 4532 participants. In subgroup analyses, there was no clear pattern of differences between geographic regions. We downgraded the evidence for the prognostic effect of IH versus normoglycaemia to low-certainty evidence due to study limitations because many studies did not adequately adjust for confounders. Imprecision and inconsistency required further downgrading due to wide 95% CIs and wide 95% prediction intervals (sometimes ranging from negative to positive prognostic factor to outcome associations), respectively.This evidence is up to date as of 26 February 2018.

AUTHORS' CONCLUSIONS

Overall prognosis of people with IH worsened over time. T2DM cumulative incidence generally increased over the course of follow-up but varied with IH definition. Regression from IH to normoglycaemia decreased over time but was observed even after 11 years of follow-up. The risk of developing T2DM when comparing IH with normoglycaemia at baseline varied by IH definition. Taking into consideration the uncertainty of the available evidence, as well as the fluctuating stages of normoglycaemia, IH and T2DM, which may transition from one stage to another in both directions even after years of follow-up, practitioners should be careful about the potential implications of any active intervention for people 'diagnosed' with IH.

Relative contributions of preprandial and postprandial glucose exposures, glycemic variability, and non-glycemic factors to HbA 1c in individuals with and without diabetes

BACKGROUND/OBJECTIVE

There is substantial interest in dietary approaches to reducing postprandial glucose (PPG) responses, but the quantitative contribution of PPG to longer-term glycemic control (reflected in glycated hemoglobin, HbA_1c) in the general population is not known. This study quantified the associations of preprandial glucose exposure, PPG exposure, and glycemic variability with HbA_1c and estimated the explained variance in HbA_1c in individuals with and without type 2 diabetes (T2D).

SUBJECTS/METHODS

Participants in the A1c-Derived Average Glucose (ADAG) study without T2D (n = 77) or with non-insulin-treated T2D and HbA_1c<6.5% (T2D_{HbA1c < 6.5%}, n = 63) or HbA_1c ≥ 6.5% (T2D_{HbA1c ≥ 6.5%}, n = 34) were included in this analysis. Indices of preprandial glucose, PPG, and glycemic variability were calculated from continuous glucose monitoring during four periods over 12 weeks prior to HbA_1c measurement. In linear regression models, we estimated the associations of the glycemic exposures with HbA_1c and calculated the proportion of variance in HbA_1c explained by glycemic and non-glycemic factors (age, sex, body mass index, and ethnicity).

RESULTS

The factors in the analysis explained 35% of the variance in HbA_1c in non-diabetic individuals, 49% in T2D_{HbA1c < 6.5%}, and 78% in T2D_{HbA1c ≥ 6.5%}. In non-diabetic individuals PPG exposure was associated with HbA_1c in confounder-adjusted analyses (P < 0.05). In the T2D_{HbA1c < 6.5%} group, all glycemic measures were associated with HbA_1c (P < 0.05); preprandial glucose and PPG accounted for 14 and 18%, respectively, of the explained variation. In T2D_{HbA1c ≥ 6.5%}, these glycemic exposures accounted for more than 50% of the variation in HbA_1c and with equal relative contributions.

CONCLUSIONS

Among the glycemic exposures, PPG exposure was most strongly predictive of HbA_1c in non-diabetic individuals, suggesting that interventions targeting lowering of the PPG response may be beneficial for long-term glycemic maintenance. In T2D, preprandial glucose and PPG exposure contributed equally to HbA_1c.

A low-carbohydrate survey: Evidence for sustainable metabolic syndrome reversal

Background: Metabolic syndrome has become a significant problem, with the American Diabetes Association estimating the cost of diabetes and pre-diabetes in the United States alone to be $322 billion per year. Numerous clinical trials have demonstrated the efficacy of low-carbohydrate diets in reversing metabolic syndrome and its associated disorders.Aim: This study was designed to examine how voluntary adherents to a low-carbohydrate diet rate its effectiveness and sustainability using an online survey.Setting and methods: The 57-question survey was administered online and shared internationally via social media and ‘low-carb’ communities. Where appropriate, chi-squared tests and paired t-tests were used to analyse the responses.Results: There were 1580 respondents. The majority of respondents had consumed less than 100 g of carbohydrates per day for over a year, typically for reasons of weight loss or disease management. There was a reported decrease in waist circumference and weight with a simultaneous decrease in hunger and increase in energy level. Of those who provided laboratory values, the majority saw improvements in their HbA1c, blood glucose measurements, and lipid panel results. There was a reduction in usage of various medications, and 25% reported medication cost savings, with average monthly savings of $288 for those respondents. In particular, the usage of pain relievers and anti-inflammatories dropped with a simultaneous decreased rating of pain and increase in mobility.Conclusion: We conclude that low-carbohydrate diets are a sustainable method of metabolic syndrome reversal in a community setting.

Glycated haemoglobin A1c as a risk factor of cardiovascular outcomes and all-cause mortality in diabetic and non-diabetic populations: a systematic review and meta-analysis

OBJECTIVE

To examine the relationship between glycated haemoglobin A1c (HbA1c) levels and the risk of cardiovascular outcomes and all-cause mortality based on data from observational studies and to determine the optimal levels of HbA1c for preventing cardiovascular events and/or mortality in diabetic and non-diabetic populations.

REVIEW METHODS

We systematically searched Medline, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews and Web of Science databases, from inception to July 2016, for observational studies addressing the association of HbA1c levels with mortality and cardiovascular outcomes. Random effects models were used to compute pooled estimates of HR and respective 95% CI for all-cause mortality, cardiovascular mortality and risk of cardiovascular events, separately for people with and without diabetes.

RESULTS

Seventy-four published studies were included in the systematic review, but only 46 studies could be incorporated in the meta-analysis. In both diabetic and non-diabetic populations, there was an increase in the risk of all-cause mortality when HbA1c levels were over 8.0% and 6.0%, respectively. The highest all-cause mortality in people with diabetes was HbA1c above 9.0% (HR=1.69; 95% CI 1.09 to 2.66) and in those without diabetes was HbA1c above 6.0% (HR=1.74; 95% CI 1.38 to 2.20). However, both diabetic and non-diabetic populations with lower HbA1c levels (below 6.0% HR=1.57; 95% CI 1.14 to 2.17 and below 5.0% HR=1.19; 95% CI 1.04 to 1.36, respectively) had higher all-cause mortality. Similar pooled estimates were found when cardiovascular mortality was the outcome variable.

CONCLUSION

HbA1c is a reliable risk factor of all-cause and cardiovascular mortality in both diabetics and non-diabetics. Our findings establish optimal HbA1c levels, for the lowest all-cause and cardiovascular mortality, ranging from 6.0% to 8.0% in people with diabetes and from 5.0% to 6.0% in those without diabetes.

The effects of physical activity interventions on glycated haemoglobin A1c in non-diabetic populations: a protocol for a systematic review and meta-analysis

INTRODUCTION

Epidemiological evidence suggests that physical activity has a positive effect on reducing glycated haemoglobin A1c (HbA1c) levels not only in diabetics, but also in healthy subjects. Moreover, a positive association of HbA1c levels with cardiovascular disease and mortality in non-diabetic populations has recently been reported. This is a protocol for a systematic review and meta-analysis aiming to estimate the effects of physical activity on glycaemic control measured by HbA1c levels in non-diabetic populations; and to determine which type of physical activity has a greater influence on glycaemic control.

METHODS AND ANALYSIS

The search will be conducted using MEDLINE, EMBASE, the Cochrane Library and Web of Science databases from inception to mid-2017. Randomised controlled trials, non-randomised experimental studies and controlled pre-post studies written in English, Portuguese, French or Spanish will be included. The Cochrane Collaboration's tool and The Quality Assessment Tool for Quantitative Studies will be used to assess the risk of bias for studies included in the systematic review. Standardised pre-post intervention mean differences of HbA1c will be calculated as the primary outcome. Subgroup analyses will be performed based on the characteristics of physical activity intervention and population included in the studies.

ETHICS AND DISSEMINATION

This systematic review will synthesise evidence on the association of physical activity and HbA1c in non-diabetic populations. This study is important from the clinical and public health point because it will estimate the effect of physical activity on the glycemic control, and it will also examine which is the type of physical activity that should be recommended for preventing type 2 diabetes and its complications. The results will be disseminated by publication in a peer-reviewed journal. Ethical approval will not be required because the data used for this systematic review will be obtained from published studies and there will be no concerns about privacy.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42016050991.

Oxidized LDL but not total LDL is associated with HbA1c in individuals without diabetes

OBJECTIVE

This study investigates the association between HbA1c, LDL and oxi-LDL in individuals without diabetes (DM).

METHODS

One hundred and ninety-six individuals, without DM, were enrolled and divided into three groups according to HbA1c and fasting plasma glucose values. HbA1c, oxi-LDL, LDL, and other biochemical measurements of lipid profile were also carried out.

RESULTS

oxi-LDL levels showed significant differences among all groups and group 3 presented higher values [34U/L (27-46); 44U/L (37-70); and 86U/L (49-136); p<0.001; for groups 1, 2 and 3, respectively]. There was also a significant difference in oxi-LDL/HDL and oxi-LDL/LDL ratios among all groups (p<0.001). There was no significant difference in total cholesterol (TC), triglycerides and LDL values among groups. HbA1c showed moderate positive associations with oxi-LDL (r=0.431; p<0.001), oxi-LDL/HDL ratio (r=0.423, p<0.001), and oxi-LDL/LDL ratio (r=0.359, p<0.001). There were lower associations between HbA1c and TC (r=0.142; p=0.048), triglycerides (r=0.155; p=0.030), LDL (r=0.148; p=0.039), non-HDL (r=0.192; p=0.007) and Apo B (r=0.171, p<0.001). The positive associations between HbA1c and oxi-LDL, oxi-LDL/HDL and oxi-LDL/LDL ratios remained significant even after adjustment by multiple linear regression analysis for the variables alcohol consumption, use of medicine, BMI, and age.

CONCLUSIONS

oxi-LDL levels are significantly associated with HbA1c in non-diabetic individuals. However, the levels of traditional atherogenic lipids only showed a weak association with HbA1c levels. Those at high risk of developing DM or cardiovascular disease have higher levels of oxi-LDL. These data favor to the use of HbA1c as a biomarker to identify individuals at risk of developing complications even in non-diabetic glycemic levels.

HbA1c-Based Score Model for Predicting Death Risk in Patients with Hepatocellular Carcinoma and Type 2 Diabetes Mellitus

Aim. To establish a new score model to predict risk of death in patients with hepatocellular carcinoma and type 2 diabetes mellitus. Methods. This was a retrospective study of 147 patients with hepatocellular carcinoma and type 2 diabetes mellitus who came to Beijing Ditan Hospital between October 2008 and June 2013. Univariate and multivariate logistic regression analysis was performed to obtain the independent factors associated with death risk. A new score model was devised according to these factors. Results. A prediction score model composed of HbA1c, NLR, age, and CTP class was devised, which ranged from 0 to 7. AUROC of the score was 0.853 (P < 0.001, 95% CI: 0.791-0.915). Scores 0-2, 3-4, and 5-7 identified patients as low-, medium-, and high-risk categories. The cumulative survival rate was 93.6%, 83.0%, and 74.5% in the low-risk group in 1, 2, and 3 years, while it was 64.0%, 46.0%, and 26.0% in the medium-risk group, whereas it was 24.0%, 12.0%, and 6.0% in the high-risk group, respectively. The cumulative survival rate was significantly higher in the low-risk group than that in the medium-risk group and high-risk group (P < 0.001). Conclusion. The HbA1c-based score model can be used to predict death risk in patients with hepatocellular carcinoma and type 2 diabetes mellitus.

Association of Family History of Type 2 Diabetes with Prostate Cancer: A National Cohort Study

Background

Personal history of type 2 diabetes mellitus (T2DM) is associated with a lower incidence of prostate cancer, but the underlying mechanisms are largely unknown. We hypothesized that genetic factors that are involved in the development of T2DM might protect against prostate cancer.

Methods

We used a few Swedish registers, including the Swedish Multigeneration Register and the Cancer Register, to examine the risk of prostate cancer among men with a family history of T2DM. Standardized incidence ratios were used to calculate the relative risk.

Results

The overall risk of prostate cancer among men with a familial history of T2DM was 0.87 (95% CI: 0.86–0.89) as compared to matched controls. The risk was even lower for those multiple affected relatives with T2DM, and it was 0.86 for those with two affected relatives and 0.67 for those with three and more affected relatives.

Conclusion

Family history of T2DM was associated with a lower incidence of prostate cancer, and the risk was even lower for those with more than one affected relative. Our study strongly suggests that genetic factors or shared familial factors, such as obesity, that contributed to T2DM may protect against prostate cancer.