The relationship of hospital admission and fatality from myocardial infarction to glycohaemoglobin levels

Prognostic value of HbA1c for in-hospital and short-term mortality in patients with acute coronary syndrome: a systematic review and meta-analysis

Background

HbA1c, the most commonly used indicator of chronic glucose metabolism, is closely associated with cardiovascular disease. However, the relationship between HbA1c and the mortality of acute coronary syndrome (ACS) patients has not been elucidated yet. Here, we aim to conduct a systematic review assessing the effect of HbA1c on in-hospital and short-term mortality in ACS patients.

Methods

Relevant studies reported before July 2019 were retrieved from databases including PubMed, Embase, and Central. Pooled relative risks (RRs) and the corresponding 95% confidence interval (CI) were calculated to evaluate the predictive value of HbA1c for the in-hospital mortality and short-term mortality.

Results

Data from 25 studies involving 304,253 ACS patients was included in systematic review. The pooled RR of in-hospital mortality was 1.246 (95% CI 1.113–1.396, p: 0.000, I² = 48.6%, n = 14) after sensitivity analysis in studies reporting HbA1c as categorial valuable. The pooled RR was 1.042 (95% CI 0.904–1.202, p: 0.57, I² = 82.7%, n = 4) in random-effects model for studies reporting it as continuous valuable. Subgroup analysis by diabetic status showed that elevated HbA1c is associated increased short-term mortality in ACS patients without diabetes mellitus (DM) history and without DM (RR: 2.31, 95% CI (1.81–2.94), p = 0.000, I² = 0.0%, n = 5; RR: 2.56, 95% CI 1.38–4.74, p = 0.003, I² = 0.0%, n = 2, respectively), which was not the case for patients with DM and patients from studies incorporating DM and non-DM individuals (RR: 1.16, 95% CI 0.79–1.69, p = 0.451, I² = 31.9%, n = 3; RR: 1.10, 95% CI 0.51–2.38), p = 0.809, I² = 47.4%, n = 4, respectively).

Conclusions

Higher HbA1c is a potential indicator for in-hospital death in ACS patients as well as a predictor for short-term mortality in ACS patients without known DM and without DM.

Causes and consequences of hyperglycemia in critical illness

PURPOSE OF REVIEW

This article reviews recent epidemiologic and intervention studies addressing the impact of hyperglycemia on morbidity and mortality in critically ill patients. It also discusses a growing body of literature examining why elevated blood glucose occurs in hospitalized patients without previously recognized diabetes.

RECENT FINDINGS

Hyperglycemia is highly prevalent in the intensive care unit. Numerous observational studies have demonstrated the association between hyperglycemia and adverse outcomes, independent of pre-existing diabetes. Intervention trials of insulin therapy are limited but overall demonstrate that glucose lowering significantly improves outcomes. The ideal target for blood glucose and the population that would benefit most from intervention remain controversial. Less frequently studied than the consequences, the causes of hyperglycemia occurring during critical illness remain unclear. Although glucose abnormalities in hospitalized patients have traditionally been explained by mediators of stress, a growing body of evidence has examined whether underlying defects in glucose metabolism may also be important contributors.

SUMMARY

In general, evidence suggests that hyperglycemia is a potentially correctable abnormality that has deleterious effects in critically ill individuals. Hyperglycemic patients without previously recognized diabetes appear to be particularly vulnerable, and thus further examination of the mechanisms underlying the development of elevated blood glucose is warranted.

Prognostic value of admission plasma glucose and HbA in acute myocardial infarction

OBJECTIVE

Stress hyperglycaemia increases the risk of mortality after acute myocardial infarction in diabetic and in non-diabetic patients. We aimed to determine the contribution of admission plasma glucose and HbA(1c) on post-acute myocardial infarction prognosis.

PATIENTS AND METHODS

Admission plasma glucose and HbA(1c) were simultaneously measured in all patients consecutively hospitalized for acute myocardial infarction. Patient survival was measured on 5 and 28 days after admission. Patients were defined as having 'previously diagnosed diabetes' (personal history of diabetes defined using ADA 1997 criteria), 'no diabetes', those without previously diagnosed diabetes and HbA(1c) below 6.5%, or 'possible diabetes', i.e. those without previously diagnosed diabetes and HbA(1c) above 6.5%.

RESULTS

Of the 146 patients included, four had died by day 5 and 14 by day 28. Admission plasma glucose was higher in patients who had died by day 28 (11.7 +/- 5.8 vs. 8.0 +/- 3.3 mmol/l, P = 0.002), whereas HbA(1c) was not (6.4 +/- 1.9 vs. 6.1 +/- 0.8%, NS). Admission plasma glucose was significantly higher in those who had died by day 28 after adjustment on HbA(1c). A multivariate analysis, including sex, age and heart failure prior to acute myocardial infarction, showed that admission plasma glucose concentration was an independent predictor of survival after acute myocardial infarction. Twenty-seven of the patients had previously diagnosed diabetes and 119 had no history of diabetes. Eleven were found to have possible diabetes. Admission plasma glucose was significantly higher in previously diagnosed diabetes (11.1 +/- 5.6) than in the other groups: 7.7 +/- 2.9 in non-diabetes, 8.2 +/- 2.1 in possible diabetes (P < 0.0001). The relationship between HbA(1c)-adjusted admission plasma glucose and mortality after acute myocardial infarction was also found in the non-diabetes group.

CONCLUSIONS

Admission plasma glucose, even after adjustment on HbA(1c), is a prognostic factor associated with mortality after acute myocardial infarction. Acute rather than the chronic pre-existing glycometabolic state accounts for the prognosis after acute myocardial infarction.

Elevated glycated haemoglobin in non-diabetic patients is associated with an increased mortality in myocardial infarction

Diabetes is associated with increased mortality following acute myocardial infarction compared to the general population. Elevated glycated haemoglobin (HbA1c) in diabetic patients is also associated with increased mortality following acute myocardial infarction, while mild elevation in HbA1c are associated with impaired glucose tolerance. The aim of this study was to determine the influence of HbA1c on outcome of acute myocardial infarction in 253 non-diabetic patients, 46 of whom died in one year. In univariate analysis, risk factors for death included smoking, glucose, cholesterol and HbA1c. In logistic regression analysis HbA1c was an independent risk factor for death. Over one-third of the fatality group had an HbA1c in the highest quartile, compared to one-fifth of the surviving group (p = 0.02). Elevated HbA1c is a risk marker for short-term mortality following acute myocardial infarction in non-diabetic subjects.

Association of early-onset coronary heart disease in South Asian men with glucose intolerance and hyperinsulinemia

BACKGROUND

Rates of coronary heart disease are higher in South Asians (Indians, Pakistanis, and Bangladeshis) settled overseas than in other ethnic groups. We tested the hypothesis that this excess risk results from metabolic disturbances associated with insulin resistance.

METHODS AND RESULTS

There were 1,421 South Asian men and 1,515 European men aged 40-69 years in London examined in the Southall Study. Prevalence of ischemic ECG abnormalities was higher in South Asians than in Europeans (17% versus 12%, p < 0.001), with an excess of major Q waves (Minnesota codes 1-1 or 1-2) in younger South Asian men (p = 0.01 for the age-ethnicity interaction). Major Q waves were strongly associated with glucose intolerance and hyperinsulinemia in younger South Asians; these factors accounted statistically for 73% of major Q waves in those aged 40-54 years. Age-standardized prevalence of a positive history of coronary heart disease was similar in South Asians and Europeans (8.5% versus 8.2%, NS), and positive history without Q waves was not associated with glucose intolerance or hyperinsulinemia in South Asians. Smoking rates and average plasma cholesterol were lower in South Asians than in Europeans; in a logistic model controlling for smoking and cholesterol, the odds ratio for major Q waves in South Asians compared with Europeans was 2.4 (95% CI, 1.5-3.8). Adjusting for glucose intolerance and hyperinsulinemia reduced this ratio to 1.5 (95% CI, 0.9-2.5).

CONCLUSIONS

These results are consistent with the hypothesis that insulin resistance underlies the high coronary risk in South Asian people and strengthen the evidence for a fundamental role of this metabolic pattern in the etiology of coronary heart disease.

Misclassification of diabetic subjects may account for the increased vascular risk of impaired glucose tolerance: the Islington Diabetes Survey

We have studied the associations of macrovascular disease and hypertension with impaired glucose tolerance in a recall sample of 223 subjects selected from a population aged greater than or equal to 40 years who had been screened for diabetes using two separate glucose tolerance tests. Blood pressure was higher in subjects with diabetes, but not in those with impaired glucose tolerance, than in normals. Coronary heart disease, based on ECG criteria and history, was more frequent both in subjects with impaired glucose tolerance (odds ratio 1.94, 95% CI 1.02-3.69) and those with diabetes (odds ratio 3.88, 95% CI 1.33-11.97) than in normals, but the excess in the impaired glucose tolerance group was reduced, and was no longer significant, when adjusted for other variables (odds ratio 1.29, 95% CI 0.62-2.66). Peripheral vascular disease was more frequent in subjects with diabetes, but not in those with impaired glucose tolerance. When the subjects with impaired glucose tolerance on a single test were reclassified according to the results of a separate glucose tolerance test, the prevalence of coronary heart disease increased significantly with increasing degrees of glucose intolerance. Subjects with impaired glucose tolerance on both tests had an adjusted odds ratio of coronary heart disease of 0.90 (95% CI 0.42-1.94) compared with normal subjects. The excess of macrovascular disease in subjects with impaired glucose tolerance may result, at least in part, from the admixture of 'false negative diabetics' in that class.