Update on pre-diabetes: Focus on diagnostic criteria and cardiovascular risk

Is pre-diabetes a predictor of events in patients with atrial fibrillation?

BACKGROUND

Diabetes mellitus (DM) increases the probability of presenting atrial fibrillation (AF) and it is a predictor of its ischemic stroke. There is limited information of the association between glycated hemoglobin (HbA1c) levels and ischemic, embolic or bleeding events in patients with pre-DM and AF.

METHODS

To investigate whether the presence of pre-DM in patients with AF predicts ischemic or bleeding events, myocardial infarction or mortality, we performed a retrospective study with a final cohort of 2993 non-diabetic patients with AF and data of glycated hemoglobin (HbA1c). We divided the cohort in two groups: those with normal glucose (n = 1351) and those with pre-diabetes (n = 1642). Incidence rates were calculated as the number of events per 100 person-years and were then compared between groups. Competitive hazard regression analysis for non-fatal events(death as the competing event) and conventional Cox regression for mortality were performed.

RESULTS

There was not difference between groups for incidence rates of the different events per 100 person-years. Even considering HbA1c as continuous variable, the unadjusted analysis showed no relation between levels of HbA1c and more risk of events. This association remained not significant after adjustment for CHA2DS2-VASc score, HAS-BLED score and anticoagulation therapy.

CONCLUSION

In this study of 2993 non-diabetic patients with new-onset AF, we have not found an association between HbA1c and worse prognosis when it is in the range of pre-diabetes.

School-based Study of the Prevalence and Associated Factors of Prediabetes Among Adolescents in Kano, Nigeria

Background

Prediabetes and diabetes are important metabolic public health problems, especially among adolescents. However, they are being given little or no attention, especially in Sub-Saharan Africa (SSA). Prediabetes increases the risk of developing type 2 diabetes mellitus (T2DM) and cardiovascular diseases.

Objective

To determine the prevalence of prediabetes and its associated factors among adolescents in Kano, northwest, Nigeria.

Methods

This was a cross-sectional study of 650 secondary school students aged 10-19 years in Tarauni LGA of Kano state. A self-administered questionnaire was used to obtain the socio-demographic data and family history of diabetes of the participants. Each participant had his/her FBS and OGTT measured. Prediabetes was defined using the ISPAD criteria (FBS of 5.6-6.9mmol/L and 2HPP glucose level of 7.8-11.0mm). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined for the FBG test against the OGTT test. Bivariate and multivariate logistic regressions were done to ascertain the associated factors of prediabetes.

Results

There were 372 females and 278 males. The age range was 10-19 years with a mean 14.9±1.8 years. The prevalence of prediabetes using FBG was 5.5% while using OGTT was 8.9%, while 0.6% of students had combined IFG/IGT. FBG had a sensitivity of 7%, specificity of 95%, PPV of 11% and a NPV of 91%. Male gender (AOR=2.56, C.I= 1.25 - 5.23) and socioeconomic class (AOR= 3.36, C.I = 1.32 - 8.54) were found to be associated with IFG while positive family history of diabetes (AOR= 0.39, C.I = 0.18 - 0.84) was associated with IGT.

Conclusion

Prediabetes is common among the study population and the sex-specific prevalence rate was higher among males. Higher socioeconomic class and a positive family history of diabetes were significant associations.

Decreased Sestrin levels in patients with type 2 diabetes and dyslipidemia and their association with the severity of atherogenic index

PURPOSE

We earlier reported that Sestrin2 regulates monocyte activation and atherogenic events through AMPK-mTOR nexus under high-glucose and dyslipidemic conditions. However, the statuses of Sestrins in diabetes and dyslipidemia are not known. We report here on the status of Sestrins and their association with diabetic dyslipidemia and atherosclerosis.

METHODS

Individuals with normal glucose tolerance (NGT) (n = 46), dyslipidemia (n = 42), and patients with Type 2 diabetes with (n = 41) and without dyslipidemia (n = 40) were recruited from a tertiary diabetes centre, Chennai, India to study the mRNA expression levels of Sestrins (1, 2, and 3) in monocytes by RT-qPCR. Serum levels of Sestrins were measured using ELISA. Atherogenic index of plasma was calculated as log (triglyceride/HDL).

RESULTS

mRNA expressions of Sestrin1 and Sestrin3 were significantly reduced in monocytes under dyslipidemic conditions but not in diabetes condition. Interestingly, Sestrin2 mRNA expression was significantly reduced in all disease conditions including dyslipidemia, and diabetes with and without dyslipidemia. Sestrin2 mRNA levels were negatively correlated with glycemic and lipid parameters and plasma atherogenic index. Furthermore, circulatory Sestrin2 was also found to be significantly decreased in dyslipidemia (415.2 ± 44.7 pg/ml), diabetes (375 ± 45 pg/ml), and diabetes with dyslipidemia (319.2 ± 26.3 pg/ml) compared to NGT (706.3 ± 77 pg/ml) and negatively correlated with glycemic, lipid parameters, and plasma atherogenic index.

CONCLUSION

We report for the first time that Sestrins levels are significantly decreased in diabetes and dyslipidemic conditions. More strikingly, Sestrin2 had a strong association with atherogenic risk factors and severity of atherogenic index and we suggest that Sestrin2 may be used as a biomarker for assessing atherogenesis.

Novel molecular markers of cardiovascular disease risk in type 2 diabetes mellitus

Diabetes represents the leading risk factor for the development of cardiovascular disease (CVD). Chronic hyperglycemia and/or acute post-prandial changes in blood glucose determine an increase in reactive oxygen species (ROS), which play a fundamental role in endothelial dysfunction and in the nuclear transport of pro-atherogenic transcription factors that activate the "inflammasome". In addition, the glycemic alteration favors the formation and stabilization of atherosclerotic plaque through the mechanism of non-enzymatic glycation of different molecules, with the establishment of the so-called "advanced glycosylation end products" (AGE). Laboratory information provided by the level of biomarkers could make a quantitative and qualitative contribution to the clinical process of screening, prediction, prevention, diagnosis, prognosis and monitoring of cardiovascular (CV) risk linked to diabetes. This review describes the importance of specific biomarkers, with particular focus on novel ones, for stratifying and management of diabetes CV risk.

Assessing Cardiovascular Risk in Patients with Diabetes: An Update

The globalization of the Western lifestyle has resulted in increase of diabetes mellitus, a complex, multifactorial disease. Diabetes mellitus is a condition often related to the disorders of the cardiovascular system. It is well established that three quarters of diabetics, aged over 40, will die from cardiovascular disease and are more likely than non-diabetics to die from their first cardiovascular event. Therefore, it is of paramount importance to individualize treatment via risk stratification. Conditions that increase cardiovascular risk in people with diabetes include age more than 40 years, male gender, history of relative suffering from premature CHD, blood pressure and high LDL levels, presence of microalbuminuria, obstructive sleepapnea, erectile dysfunction and other conditions.

Several models have been developed in order to assess cardiovascular risk in people with and without diabetes. Some of them have been proven to be inadequate while others are widely used for years. An emerging way of risk assessment in patients with diabetes mellitus is the use of biomarkers but a lot of research needs to be done in this field in order to have solid conclusions.

Expression and clinical significance of miR-1 and miR-133 in pre-diabetes

Pre-diabetes represents an intermediate state of altered glucose metabolism between normal glucose levels and type 2 diabetes mellitus (T2D), and is considered a significant risk factor for the development of T2D and related complications. Early detection of pre-diabetes may allow for the use of timely and effective treatment strategies to prevent its progression. Circulating microRNAs (miRNAs/miRs) that reflect changes in diabetes-related tissues, including the pancreas, liver, skeletal and heart muscle, and adipose tissue are promising biomarkers of disease progression. In our previous study, it was demonstrated that the cardiac and skeletal muscle specific miR-1 and miR-133 are upregulated in the blood of patients with T2D and cardiovascular disease. Since both miRNAs have been shown to be implicated in insulin resistance, an important feature of pre-diabetes, we hypothesised that their expression may be increased prior to clinical diagnosis of T2D, and may thus serve as biomarkers for pre-diabetes. The expression levels of circulating miRNAs were evaluated by reverse transcription-quantitative PCR in whole blood samples from 55 subjects, including 28 pre-diabetes individuals with impaired fasting glucose (FG) and impaired glucose tolerance, and 27 healthy controls. The individuals with pre-diabetes exhibited significantly higher expression levels of miR-1 and miR-133 compared with the controls (P<0.05). Target prediction search revealed that both miR-1 and miR-133 target several pathways involved in the pathophysiology of diabetes. Pearson's correlation analysis revealed that the two miRNAs were positively correlated with blood glucose parameters, including FG, 2-h oral glucose tolerance test and glycated haemoglobin A1c levels, as well as with insulin resistance (P<0.05). Multivariate logistic regression analysis revealed that the two miRNAs were significantly and directly associated with pre-diabetes, and this association remained significant after adjustment for several confounding variables (P<0.05). Moreover, linear regression analysis showed that the Homeostatic Model Assessment-Insulin Resistance was the only significant predictor to be significantly associated with both miRNAs (P<0.05). In discriminating pre-diabetes individuals from healthy controls, the area under the curves (AUCs) of the receiver operating characteristic curves (ROCs) were 0.813 and 0.810 for miR-1 and miR-133 respectively (P<0.05). Despite the relatively small number of participants, the present study showed for the first time that circulating levels of miR-1 and miR-133 were increased in individuals with pre-diabetes, and they were associated with important features of pre-diabetes. Thus, they may serve as clinical biomarkers for the early-stages of T2D.

The Risk Threshold for Hemoglobin A1c Associated With Albuminuria: A Population-Based Study in China

BACKGROUND

Diabetic kidney disease (DKD) is a kind of common microvascular complication of diabetes. This study aims to explore the possible links between blood sugar level and albuminuria, providing the exact cut point of the "risk threshold" for blood glucose with DKD.

METHODS

The relationship between blood glucose and albuminuria was modeled using linear and logistic regression in the REACTION study cohorts (N= 8932). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression model. Two-slope linear regression was used to simulate associations between blood glucose and ACR.

RESULTS

We found that the increase in ACR was accompanied by increased HbA1c, with a turning point at 5.5%. The positive correlation remained highly significant (P<0.001) when adjusted for age, sex, marital status, education, smoking status, drinking status, BMI, waistline, SBP and DBP. In subgroup analyses including gender, obesity, hypertension, and smoking habits, the relationship was significant and stable.

CONCLUSIONS

We determined a risk threshold for HbA1c associated with albuminuria in a Chinese population over the age of 40. HbA1c ≥ 5.5% was positively and independently associated with ACR. These results suggest the necessity of early blood glucose control and renal function screening for DKD in at-risk populations.

Arterial hypertension and diastolic blood pressure associate with aortic stenosis

OBJECTIVES

Due to age-related differences in aortic valve structure, it is likely that the pathophysiology of aortic stenosis (AS) and associated risk factors differ between age groups. Here we prospectively studied the influence of traditional cardiovascular risk factors on AS development requiring surgery among patients without concomitant coronary artery disease (CAD) and stratified for age.

DESIGN

This study included 322 patients, who had prior to surgery for AS participated in population-based surveys, and 131 of them had no visible CAD upon preoperative coronary angiogram. For each case, we selected four referents matched for age, gender, and geographic area. To identify predictors for surgery, we used multivariable conditional logistic regression with a model including arterial hypertension (or measured blood pressure and antihypertensive medication), cholesterol levels, diabetes, body mass index (BMI), and smoking.

RESULTS

In patients without CAD, future surgery for AS was associated with arterial hypertension and elevated levels of diastolic blood pressure in patients younger than 60 years at surgery (odds ratio [95% confidence interval]), (3.40 [1.45-7.93] and 1.60 [1.09-2.37], respectively), and with only impaired fasting glucose tolerance in patients 60 years or older at surgery (3.22 [1.19-8.76]).

CONCLUSION

Arterial hypertension and elevated diastolic blood pressure are associated with a risk for AS requiring surgery in subjects below 60 years of age. Strict blood pressure control in this group is strongly advocated to avoid other cardiovascular diseases correlated to hypertension. If hypertension and elevated diastolic blood pressure are risk factors for developing AS requiring surgery need further investigations. Notably, elevated fasting glucose levels were related to AS requiring surgery in older adults without concomitant CAD.

Prognostication of clinical outcomes in diabetes mellitus: Emerging role of cardiac biomarkers

Type 2 diabetes mellitus (T2DM) remains substantial health problem and one of the most prevalent metabolic diseases worldwide. The impact of T2DM on CV mortality and morbidity is embedded through a nature evolution of the disease and is modulated by numerous risk factors, such as hypertension, obesity, dyslipidemia. There is large body of evidence regarding use of the cardiac biomarkers to risk stratification at higher CV risk individuals who belongs to general population and cohort with established CV disease. Although T2DM patients have higher incidence of cardiac and vascular complications than the general population, whether cardiac biomarkers would be effective to risk stratification of the T2DM is not fully understood. The aim of the review is to summarize our knowledge regarding clinical implementation of cardiac biomarkers in risk assessment for T2DM patients. The role of natriuretic peptides, soluble ST2, galectin-3, growth differentiation factor-15, and cardiac troponins are widely discussed.

Correlation between DXA and laboratory parameters in normal weight, overweight, and obese patients

OBJECTIVE

The aim of this study was to review the existence and types of correlations between body composition densitometric parameters and laboratory values associated to cardiometabolic risk.

METHODS

We retrospectively analyzed data from 316 individuals in the weight range from normality to super-obesity, submitted to total body dual-energy x-ray absorptiometry (DXA) scans and routine biochemistry at S.Orsola-Malpighi Hospital from June 2010 to March 2014. The study included 182 women, 45.8 ± 13.4 y of age, with a body mass index (BMI) of 31.5 (± 11) kg/m² (group F) and 134 men, 45.4 ± 13.6 y of age, with a BMI of 27.6 (± 7.8) kg/m² (group M). All patients underwent whole-body scan (Lunar iDXA, GE Healthcare, Madison, WI, USA) and laboratory analysis (blood fasting glucose, total cholesterol, high-density lipoprotein cholesterol, tricylglycerides [TGs], aspartate aminotransferase, and alanine aminotransferase). Correlation between laboratory values and total body and regional fat mass (including visceral adipose tissue [VAT] and subcutaneous adipose tissue in the android region), and lean mass parameters were analyzed with linear and stepwise regressions analysis (significance limit, P < 0.05). Receiver operating characteristic curves were performed to assess the accuracy of the best-fit DXA parameter (VAT) to identify at least one laboratory risk factor.

RESULTS

In both groups, BMI and densitometric parameters showed a linear correlation with fasting blood glucose and TG levels and an inverse correlation with high-density lipoprotein cholesterol (P < 0.05), whereas no correlation was observed with total cholesterol levels. The only densitometric parameter retained in the final model of stepwise multiple regression was VAT for fasting blood glucose (group F: β = 0.4627, P < 0.0001; group M: β = 0.6221, P < 0.0001) and TG levels (group F: β = 0.4931, P < 0.0001; group M: β = 0.1990, P < 0.0261) independently of BMI. The optimal cutoff points of VAT to identify the presence of at least one laboratory risk factor were >1395 g and >1479 cm³ for men and >1281 g and >1357 cm³ for women.

CONCLUSIONS

DXA analysis of VAT is associated with selected laboratory parameters used for the evaluation of cardiometabolic risk and could be per se a helpful parameter in the assessment of clinical risk.

Evaluation of the longitudinal deformation of the left ventricular myocardium in subjects with impaired fasting glucose with and without increased glycated hemoglobin

OBJECTIVE

Prediabetes comprises a heterogeneous group because of the poor concordance of its definition. The aim of our study was to evaluate the longitudinal deformation of the left ventricular (LV) myocardium at the two opposite ends of the prediabetes spectrum as defined by fasting blood sugar and glycated hemoglobin (HbA1c).

METHODS

Eighty consecutive subjects in a cross-sectional single-center study with impaired fasting glucose (IFG) (100-126 mg/dL) and without significant epicardial coronary artery stenosis seen on selective coronary angiography were included in our study and were divided into two groups based on their HbA1c levels (<5.7% and 5.7%-6.4%). The longitudinal deformation of the LV myocardium was compared between the two groups using two-dimensional speckle-tracking echocardiography (2DSTE).

RESULTS

The Student t-test, Mann-Whitney U test, or X2 test was used for data analysis, whichever was appropriate. The systolic strain (-16.1%±2.0 vs. -16.8%±2.4; p=0.214), systolic strain rate (-1.3±0.2 s-1 vs. -1.4±0.2 s-1; p=0.403), and early and late-diastolic strain rates (1.4±0.3 s-1 vs. 1.5±0.3 s-1; p=0.456 and 0.9±0.1 s-1 vs. 1.0±0.2 s-1; p=0.684, respectively) of the LV myocardium were not statistically different between the IFG subjects with and without increased HbA1c as detected using 2DSTE.

CONCLUSION

The longitudinal deformation of the LV myocardium as detected using 2DSTE in the subjects without significant epicardial coronary artery stenosis was not statistically significantly different between the IFG subjects with and without increased HbA1c.

Cardiac biomarkers in diabetes mellitus: New dawn for risk stratification?

Type 2 diabetes mellitus (T2DM) remains a leading cause of cardiovascular (CV) events and diseases worldwide. The aim of the review is to summarize our knowledge regarding clinical implementation of the biomarker-based strategy of the CV risk assessment in T2DM patient population. There is large body of evidence regarding use of the cardiac biomarkers to risk stratification at higher CV risk individuals who belongs to general population and cohort with established CV disease. Although T2DM patients have higher incidence of macrovascular and microvascular CV complications than the general population, whether cardiac biomarkers would be effective to risk stratification of the T2DM is not fully understood. The role of natriuretic peptides, galectin-3, interleukins, growth differentiation factor-15, as well as biomarkers of endothelial dysfunction are widely discussed. In conclusion, future directions, which associate with discovering of novel biomarkers and their best combinations to provide additional predictive information beyond other traditional CV risk factors, are discussed.

Lipopolysaccharide-binding protein (LBP) reverses the amyloid state of fibrin seen in plasma of type 2 diabetics with cardiovascular co-morbidities

Type 2 diabetes (T2D) has many cardiovascular complications, including a thrombotic propensity. Many such chronic, inflammatory diseases are accompanied (and may be exacerbated, and possibly even largely caused) by amyloid fibril formation. Recognising that there are few strong genetic associations underpinning T2D, but that amyloidogenesis of amylin is closely involved, we have been seeking to understand what might trigger the disease. Serum levels of bacterial lipopolysaccharide are raised in T2D, and we recently showed that fibrin(ogen) polymerisation during blood clotting can be affected strongly by LPS. The selectivity was indicated by the regularisation of clotting by lipopolysaccharide-binding protein (LBP). Since coagulopathies are a hallmark of T2D, we wondered whether they might too be caused by LPS (and reversed by LBP). We show here, using SEM and confocal microscopy, that platelet-poor-plasma from subjects with T2D had a much greater propensity for hypercoagulability and for amyloidogenesis, and that these could both be reversed by LBP. These data imply that coagulopathies are an important feature of T2D, and may be driven by ‘hidden’ LPS. Given the prevalence of amyloid formation in the sequelae of diabetes, this opens up novel strategies for both the prevention and treatment of T2D.

Proteomic approach to detect changes in hippocampal protein levels in an animal model of type 2 diabetes

In our previous study, we demonstrated that type 2 diabetes affects blood-brain barrier integrity and ultrastructural morphology in Zucker diabetic fatty (ZDF) rats at 40 weeks of age. In the present study, we investigated the possible candidates for diabetes-related proteins in the hippocampus of ZDF rats and their control littermates (Zucker lean control, ZLC), by using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF). Approximately 2756 protein spots were detected by 2D-DIGE, and an increase or decrease of more than 1.4-fold was observed for 13 proteins in the hippocampal homogenates of ZDF rats relative to those of ZLC rats. Among these proteins, we found four proteins whose levels were significantly lower in the hippocampi of ZDF rats than in those of ZLC rats: glial fibrillary acidic protein (GFAP), apolipoprotein A-I preprotein (apoAI-P), myelin basic protein (MBP), and rCG39881, isoform CRA_a. Among these proteins, apoAI-P protein levels were decreased most prominently in ZDF rats than in ZLC rats, based on Western blot analysis. In addition, immunohistochemical and Western blot studies demonstrated that MBP, not GFAP, immunoreactivity and protein levels were significantly decreased in the hippocampus of ZDF rats compared to ZLC rats. In addition, ultrastructural analysis showed that ZDF rats showed myelin degeneration and disarrangement in the hippocampal tissue. These results suggest that chronic type 2 diabetes affects hippocampal function via reduction of MBP and apoAI-P levels as well as disarrangement of myelin.