Biological variation of cardiovascular risk factors in patients with diabetes

Biological variation of cardiovascular biochemical markers in patients with Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a well-established risk factor for cardiovascular diseases. We aimed to identify the biological variation of ten cardiovascular biochemical markers in T2DM patients to aid in their interpretation.

METHODS

Blood samples for evaluating ten biomarkers were collected biweekly from 23 T2DM patients (10 men, 13 women) for three months. The analytical variability and variations of within-subject (CV_I) and between-subject (CV_G) levels were calculated, as well as the analytical performance specifications, reference change value (RCV), and index of individuality (II).

RESULTS

The levels of total cholesterol (CHOL), apolipoprotein A (apoA), homocysteine (HCY), high-sensitivity troponin T (hsTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP) differed between males and females (P < 0.05). The CV_Is or CV_Gs of the biomakers were higher than those of healthy participants in Westgard online database, except for hsTnT. Triglyceride (TG), lipoprotein (a) [Lp(a)] and NT-proBNP had relatively high CV_I, CV_G and RCV, whereas CHOL, high-density lipoprotein cholesterol (HDL-C), apoA and HCY showed low variation. Moreover, the II of HDL-C, LP(a), apoA, HCY and hsTnT was <0.6 and other biochemical markers was between 0.6 and 1.4.

CONCLUSION

The cardiovascular biochemical markers in T2DM patients showed higher CV_I or CV_G, except for hsTnT. ApoA had the lowest CV_I and CV_G values. Population-based reference intervals should be used with caution in clinical decision-making for T2DM patients.

Three-Variate Longitudinal Patterns of Metabolic Control, Body Mass Index, and Insulin Dose during Puberty in a Type 1 Diabetes Cohort: A Group-Based Multitrajectory Analysis

OBJECTIVE

To analyze the interrelationship of metabolic control, age- and sex-adjusted body mass index, and daily insulin dose and to identify heterogeneous multivariate developmental curves from childhood to young adulthood in a large cohort of children with type 1 diabetes (T1D) STUDY DESIGN: Data were extracted from the diabetes follow-up registry DPV. Longitudinal data from 9239 participants with T1D age 8-18 years with diabetes duration ≥2 years and ≥5 years of follow-up were analyzed. We applied group-based multitrajectory modeling to identify latent groups of subjects following similar developmental curves across outcomes (hemoglobin A1c [HbA1c], age/sex-standardized body mass index [BMI-SDS], daily insulin dose per kg). Group number was based on Bayes information criterion and group size (≥5%).

RESULTS

The group-based multitrajectory approach revealed 5 heterogeneous 3-variate trajectories during puberty. Individuals with stable good metabolic control, high-normal increasing BMI-SDS, and rising insulin dose patterns were classified as group 1 (33%). Group 2 (20%) comprised youths with intermediate-increasing HbA1c, low BMI-SDS, and steeply increasing insulin dose trajectories. Group 3 (11%) followed intermediate-rising HbA1c and high-normal increasing BMI-SDS developmental curves, while insulin dose increased steeply. In group 4 (14%), both high-increasing HbA1c and insulin dose trajectories were observed, while BMI-SDS was stable-normal. Group 5 (22%) included subjects with intermediate-rising HbA1c patterns, high-increasing BMI-SDS, and increasing insulin dose patterns.

CONCLUSIONS

This study identified 5 distinct 3-variate curves of HbA1c, BMI-SDS, and insulin dose during puberty among youths with T1D. This approach demonstrates a considerable heterogeneity highlighting the importance of personalized medical care.

Evaluation of biological variation of glycated hemoglobin and glycated albumin in healthy Chinese subjects

Background

Glycated hemoglobin (HbA1c) and glycated serum albumin (GSA) are used to evaluate the mean blood glucose levels. To ensure safe clinical application of HbA1c and GSA, reliable biological variation (BV) data are required. The aim of this research was to define the BV of HbA1c and GSA employing stringent rules.

Methods

Blood samples were drawn from 19 healthy subjects (10 females, nine males) once per week for 5 weeks. All samples were analyzed using enzymatic method for GSA and HPLC for HbA1c. The data were assessed for outliers, normality and variance homogeneity, and coefficient of variation (by ANOVA) for BV. Sex‐stratified BV including within‐subject (CV_I) and between‐subject (CV_G) was defined for HbA1c and GSA.

Results

The following estimates for BV values for CV_I and CV_G, respectively, were GSA: 1.23% and 4.67%, Alb: 0.75% and 3.18%, and HbA1c: 0.12% and 2.91%. The RCV of GSA was 3.61%, and HbA1c was 1.41%. And the II was 0.26 for GSA, and 0.07 for HbA1c, both of them less than 0.6. According to the 95% CI, the CV_I of HbA1c was statistically different between females and males. And both the CV_G of HbA1c and GSA were statistically different between females and males.

Conclusion

All CV_I and CV_G estimates were lower than those reported in the online BV database. And there is a significant difference between males and females. Analytical performance specifications derived from BV of this research can be applied internationally.

Assessing the impact of the diet on cardiometabolic outcomes: are multiple measurements post-intervention necessary?

The purpose of this study was to examine how using the mean of two consecutive measurements vs. one measurement post-treatment influences the sample size required to detect changes in cardiometabolic risk factors in dietary studies. For a given statistical power, using the mean of two measurements taken on consecutive days post-treatment instead of a single measurement significantly reduces the sample size required to observe changes in triglyceride, total apolipoprotein B100, and C-reactive protein concentrations in the context of a supplementation study. In the context of a controlled-feeding study, this gain is seen only in the case of change in triglyceride concentrations.

HbA1c, systolic blood pressure variability and diabetic retinopathy in Asian type 2 diabetics

BACKGROUND

The aim of the present study was to examine the association between variability in HbA1c or systolic blood pressure (SBP) and diabetes-specific moderate retinopathy in Asians with type 2 diabetes (T2D).

METHODS

A retrospective study was conducted of 172 cases of moderate diabetic retinopathy (DR) cases and 226 controls without DR, matched for age, sex, and ethnicity. Serial HbA1c and SBP (range 3-6 readings) over the 2 years prior to photographic screening of DR were collected. Intrapersonal mean and SD values for HbA1c (iM-HbA1c and iSD-HbA1c) and SBP (iM-SBP and iSD-SBP) were derived. Moderate DR was assessed from digital retinal photographs and defined as levels >43 using the Early Treatment Diabetic Retinopathy Study scale.

RESULTS

Cases of moderate DR had higher iM-HbA1c (8.2 % vs 7.3 %; P = 0.001), iSD-HbA1c (1.22 vs 0.64; P = 0.001), iM-SBP (136.8 vs 129.6 mmHg; P = 0.001) and iSD-SBP (13.3 vs 11.1; P = 0.002) than controls. In the multivariate regression model adjusted for age, gender, ethnicity, duration of diabetes, SBP, and HbA1c, iM-HbA1c and iM-SBP were significantly associated with moderate DR (odds ratio [OR] 1.80, 95 % confidence interval [CI] 1.37-2.36; and OR 1.03, 95 % CI 1.01-1.05, respectively). Neither iSD-HbA1c nor iSD-SBP were associated with moderate DR. When stratified by HbA1c <7 %, only iSD-SBP remained significantly associated with moderate DR (OR 1.11, 95 % CI 1.01-1.21).

CONCLUSION

In a cohort of Asian patients with T2D, both higher mean HbA1c levels and SBP, but not their variability, were associated with moderate DR. Among those with good glycemic control, wider variability of SBP is associated with moderate DR.

Variability of triglyceride levels and incidence of microalbuminuria in type 2 diabetes

BACKGROUND

Experimental and clinical studies have shown a strong association between hypertriglyceridemia and diabetic nephropathy. A variability of triglyceride (TG) levels has been reported in diabetes.

OBJECTIVES

To investigate the relationship of TG variability with the incidence of microalbuminuria (albumin excretion rate > 20 μg/min), in patients with type 2 diabetes.

METHODS

A longitudinal, retrospective, observational study was performed on a consecutive series of 457 normoalbuminuric outpatients, with measurements of HbA1c, lipids and microalbuminuria thrice per year with 6.8-year follow-up. TG variability, defined as standard deviation of TG (TG-SD) and TG-SD adjusted for the number of visits was calculated. A nested case-control sensitivity analysis was performed to validate the results of the primary cohort study.

RESULTS

Incident microalbuminuria (N = 124, 27.1%) was associated with higher median TG-SD (33.6 mg/dL vs 29.0 mg/dL, P < .05) and TG-SD adjusted for the number of visits (31.4 mg/dL vs 26.7 mg/dL, P < .05). At multivariate (Cox) analysis, logTG-SD and adj-logTG-SD were significant predictors of incident microalbuminuria (hazard ratio 2.1 [1.1-4.2], P = .028 and 1.5 [1.1-3.3], P = .042, respectively). In the case-control analysis, time spent with TG > 150 mg/dL during the follow-up was significantly higher in cases vs controls (27.2 ± 19 vs 16.7 ± 12.5 months, P < .05) with hazard ratio 2.0 (1.1-5.1), P < .05, for adj-logTG-SD.

CONCLUSIONS

A higher intraindividual TG variability is a predictor of incident microalbuminuria in type 2 diabetes. In addition, time of exposure to elevated TG levels (>150 mg/dL) predicts incident microalbuminuria.

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.

Associations of Plasma Kynurenines With Risk of Acute Myocardial Infarction in Patients With Stable Angina Pectoris

Objective—

Enhanced tryptophan degradation, induced by the proinflammatory cytokine interferon-γ, has been related to cardiovascular disease progression and insulin resistance. We assessed downstream tryptophan metabolites of the kynurenine pathway as predictors of acute myocardial infarction in patients with suspected stable angina pectoris. Furthermore, we evaluated potential effect modifications according to diagnoses of pre-diabetes mellitus or diabetes mellitus.

Approach and Results—

Blood samples were obtained from 4122 patients (median age, 62 years; 72% men) who underwent elective coronary angiography. During median follow-up of 56 months, 8.3% had acute myocardial infarction. Comparing the highest quartile to the lowest, for the total cohort, multivariable adjusted hazard ratios (95% confidence intervals) were 1.68 (1.21–2.34), 1.81 (1.33–2.48), 1.68 (1.21–2.32), and 1.48 (1.10–1.99) for kynurenic acid, hydroxykynurenine, anthranilic acid, and hydroxyanthranilic acid, respectively. The kynurenines correlated with phenotypes of the metabolic syndrome, and risk associations were generally stronger in subgroups classified with pre-diabetes mellitus or diabetes mellitus at inclusion ( P int ≤0.05). Evaluated in the total population, hydroxykynurenine and anthranilic acid provided statistically significant net reclassification improvements (0.21 [0.08–0.35] and 0.21 [0.07–0.35], respectively).

Conclusions—

In patients with suspected stable angina pectoris, elevated levels of plasma kynurenines predicted increased risk of acute myocardial infarction, and risk estimates were generally stronger in subgroups with evidence of impaired glucose homeostasis. Future studies should aim to clarify roles of the kynurenine pathway in atherosclerosis and glucose metabolism.

HbA1c variability as an independent risk factor for diabetic retinopathy in type 1 diabetes: a German/Austrian multicenter analysis on 35,891 patients

Objective

This study aimed to analyze the effect of HbA_1c variability on the occurrence of diabetic retinopathy in type 1 diabetes patients.

Patients and Methods

35,891 patients with childhood, adolescent or adult onset of type 1 diabetes from a large multicentre survey, the German/Austrian prospective documentation system (DPV), were analysed. Cox proportional hazard models were used to examine whether intra-individual HbA_1c variability expressed as variation coefficient is an independent risk factor for the occurrence of diabetic retinopathy.

Results

Kaplan-Meier curves stratified by median HbA_1c and variation coefficient revealed that retinopathy-free survival probability is lower when both median HbA_1c and HbA_1c variability are above the 50^th percentile. Cox regression models confirmed this finding: After adjustment for age at diabetes onset, gender and median HbA_1c, HbA_1c variability was independently associated with the occurrence of diabetic retinopathy. Time-covariate interactions used to model non-proportionality indicated an effect decreasing with duration of diabetes for both median HbA_1c and HbA_1c variability. Predictive accuracy increased significantly when adding HbA_1c variability to the Cox regression model.

Conclusions

In patients with type 1 diabetes, HbA_1c variability adds to the risk of diabetic retinopathy independently of average metabolic control.