Hyperinsulinemia and the development of ST-T electrocardiographic abnormalities. An 11-year follow-up study

Association of insulin resistance and glycemic measures with major abnormal electrocardiogram in older Chinese: Cross-sectional analysis based on the Guangzhou Biobank Cohort study

AIMS

To examine whether insulin resistance (IR) and glycemic measures were associated with major abnormal electrocardiogram (MA-ECG) and its specific abnormalities in the general population.

METHODS

Twelve-lead ECG measurements were performed on 21,720 participants without cardiovascular disease (5,918 men) from the Guangzhou Biobank Cohort Study. The participants were aged 50 years or above (mean age 61.6, standard deviation 7.1 years). Logistic regression was used to assess the associations of IR and glycemic measures with MA-ECG and specific abnormalities.

RESULTS

Ln-fasting insulin was significantly associated with MA-ECG and ST-T abnormalities (adjusted odds ratio = 1.52, 95 % confidence interval = 1.15-2.02 and 1.83, 1.37-2.45, respectively, for per standard deviation), which were stronger than those of TyG index with MA-ECG (1.08, 1.04-1.13) and ST-T abnormalities (1.16, 1.11-1.22). Ln-fasting insulin had association with Q wave abnormalities (3.19, 1.52-6.67). The association of TyG index with prolonged QTc varied by sex and obesity (P for interaction ≤ 0.01). Participants with diabetes had stronger associations of ln-fasting plasma glucose with ECG abnormalities than those without.

CONCLUSIONS

IR and glycemic measures were associated with MA-ECG, ischemia and prolonged QTc in older Chinese, especially in women, those with obesity, and those with diabetes. These findings underscore the importance of regular evaluations for these groups.

Obesity and Cardiovascular Disease: A Scientific Statement From the American Heart Association

The global obesity epidemic is well established, with increases in obesity prevalence for most countries since the 1980s. Obesity contributes directly to incident cardiovascular risk factors, including dyslipidemia, type 2 diabetes, hypertension, and sleep disorders. Obesity also leads to the development of cardiovascular disease and cardiovascular disease mortality independently of other cardiovascular risk factors. More recent data highlight abdominal obesity, as determined by waist circumference, as a cardiovascular disease risk marker that is independent of body mass index. There have also been significant advances in imaging modalities for characterizing body composition, including visceral adiposity. Studies that quantify fat depots, including ectopic fat, support excess visceral adiposity as an independent indicator of poor cardiovascular outcomes. Lifestyle modification and subsequent weight loss improve both metabolic syndrome and associated systemic inflammation and endothelial dysfunction. However, clinical trials of medical weight loss have not demonstrated a reduction in coronary artery disease rates. In contrast, prospective studies comparing patients undergoing bariatric surgery with nonsurgical patients with obesity have shown reduced coronary artery disease risk with surgery. In this statement, we summarize the impact of obesity on the diagnosis, clinical management, and outcomes of atherosclerotic cardiovascular disease, heart failure, and arrhythmias, especially sudden cardiac death and atrial fibrillation. In particular, we examine the influence of obesity on noninvasive and invasive diagnostic procedures for coronary artery disease. Moreover, we review the impact of obesity on cardiac function and outcomes related to heart failure with reduced and preserved ejection fraction. Finally, we describe the effects of lifestyle and surgical weight loss interventions on outcomes related to coronary artery disease, heart failure, and atrial fibrillation.

Resting heart rate and impaired glucose regulation in middle-aged and elderly Chinese people: a cross-sectional analysis

Background

Elevated resting heart rate (RHR) has been reported to be associated with metabolic syndrome and type 2 diabetes. The aim of this study was to explore whether a positive relationship exists between RHR and impaired glucose regulation (IGR) among middle-aged and older Chinese individuals.

Methods

We conducted a cross-sectional analysis that included a total of 9898 subjects (3194 men and 6704 women) in a Chinese population. The RHRs were derived from ECG recordings, and the subjects were stratified based on RHR quartiles.

Results

RHR levels were significantly higher in the subjects with isolated impaired fasting glucose (i-IFG), isolated impaired glucose tolerance (i-IGT), IFG + IGT and diabetes than in those with normal glucose regulation. When multivariate logistic regression analyses were performed, the odds ratios were substantially higher for the subjects with IGR (odds ratio 2.19, 95% confidence interval 1.85–2.58) in the fourth RHR quartile compared with those in the first quartile after adjustment for potential confounding covariates, and the corresponding OR for the combined IGR and type 2 diabetes group was 2.56 (95% CI 2.20–2.98, p < 0.001). Multiple regression analyses demonstrated that RHR was significantly associated with fasting plasma glucose, 2-h OGTT plasma glucose and A1c.

Conclusions

Our cross-sectional findings provide evidence that high RHR is associated with existing IGR among middle-aged and older Chinese individuals.

Effect of interactions between C peptide levels and insulin treatment on clinical outcomes among patients with type 2 diabetes mellitus

BACKGROUND

A recently halted clinical trial showed that intensive treatment of type 2 diabetes mellitus was associated with increased mortality. Given the phenotypic heterogeneity of diabetes, therapy targeted at insulin status may maximize benefits and minimize harm.

METHODS

In this longitudinal cohort study, we followed 503 patients with type 2 diabetes who were free of cardiovascular disease from 1996 until data on mortality and cardiovascular outcomes were censored in 2005. Phenotype-targeted therapy was defined as use of insulin therapy in patients with a fasting plasma C peptide level of 0.2 nmol/L or less and no insulin therapy in patients with higher C peptide levels.

RESULTS

The mean age of the cohort was 54.4 (standard deviation 13.1) years, and 56% were women. The mean duration of diabetes was 4.6 years (range 0-35.9 years). Of the 503 patients, 110 (21.9%) had a low C peptide level and 111 (22.1%) were given insulin. Based on their C peptide status, 338 patients (67.2%) received phenotype-targeted therapy (non-insulin-treated, high C peptide level [n = 310] or insulin-treated, low C peptide level [n = 28]), and 165 patients (32.8%) received non-phenotype-targeted therapy (non-insulin-treated, low C peptide level [n = 82] or insulin-treated, high C peptide level [n = 83]). Compared with the insulin-treated, low-C-peptide referent group, the insulin-treated, high-C-peptide group was at a significantly higher risk of cardiovascular events (hazard ratio [HR] 2.85, p = 0.049) and death (HR 3.43, p = 0.043); the risk was not significantly higher in the other 2 groups. These differences were no longer significant after adjusting for age, sex and diabetes duration.

INTERPRETATION

Patients with low C peptide levels who received insulin had the best clinical outcomes. Patients with normal to high C peptide levels who received insulin had the worst clinical outcomes. The results suggest that phenotype-targeted insulin therapy may be important in treating diabetes.

Hyperfibrinogenemia and metabolic syndrome in type 2 diabetes: a population-based study

BACKGROUND

It has been hypothesized that fibrinogen clusters with several components of the metabolic syndrome, thus increasing its cardiovascular risk. The aims of the present study were to assess in a large population-based cohort of patients with type 2 diabetes (1) variables associated with fibrinogen and (2) the relationship between hyperfibrinogenemia, a number of components of the metabolic syndrome, and coronary heart disease (CHD).

METHODS

We identified a cross-sectional, population-based cohort of 1574 patients with type 2 diabetes using multiple sources of ascertainment. Components of the metabolic syndrome were hypertension (systolic blood pressure > or = 160 mmHg and/or diastolic blood pressure > or = 95 mmHg and/or treatment with antihypertensive drugs), dyslipidemia (tryglicerides >2.82 mmol/l and/or HDL-cholesterol <1.03 mmol/l), hyperuricemia (uric acid >416 micromol/l) and increased albumin excretion rate (AER > or = 20 microg/min).

RESULTS

Fibrinogen increases with age, HbA(1c), smoking, hypertension and a number of components of the metabolic syndrome, even after adjustment for confounders. Prevalence of CHD increases linearly across quartiles of fibrinogen (from 26.1 to 40.6%, p=0.046). However, in logistic regression, after adjustment for both confounders and known risk factors for CHD, the role of fibrinogen is no more significant, whereas ORs for HbA(1c) between 6.8 and 8.8% and >8.8% vs values <6.8% are, respectively, 1.91 (95% CI 1.36-2.69) and 1.56 (1.07-2.27).

CONCLUSIONS

This population-based study shows that fibrinogen increases with age, HbA(1c), smoking, hypertension and a number of components of the metabolic syndrome, independent of major confounders. We also found that poor blood glucose control was associated with CHD.

Clustering of cardiovascular risk factors in hyperinsulinemia in Japanese without diabetes

Clustering of cardiovascular risk factors in hyperinsulinemia was investigated in 247 Japanese subjects without diabetes. After adjustment for age and sex, the highest quartile of the summed values of insulin concentrations after oral glucose loading showed high odds ratios (OR; 95% confidence intervals) for the prevalence of cardiovascular risk factors: OR = 2.02 (1.07-3.83) for hypertension, 3.91 (1.82-8.40) for hypertriglyceridemia, 2.41 (1.30-4.46) for low high-density lipoprotein cholesterol, 2.41 (1.28-4.51) for impaired glucose tolerance, and 3.58 (1.44-8.88) for high uric acid. Two or more of these factors were clinically elevated in 50% of those in the highest quartile of the summed values of insulin, compared to 16-28% of those in the lower three quartiles. These findings were slightly attenuated after further adjustment for body mass index and sum of skinfolds. In conclusion, multiple risk factors for cardiovascular disease existed in the subjects with hyperinsulinemia in Japanese without diabetes.