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Coronary heart disease incidence and cardiovascular mortality in Busselton with reference to glucose and insulin
Insights
Elevated one-hour serum insulin levels are linked to increased cardiovascular disease risk in men over 60. This finding suggests insulin may be an independent predictor of heart disease mortality, particularly in older males.
Area of Science:
- Epidemiology
- Cardiovascular Medicine
- Metabolic Syndrome
Background:
- Cardiovascular disease (CVD) remains a leading cause of mortality globally.
- Identifying novel risk factors beyond traditional ones like hypertension and hypercholesterolemia is crucial for effective prevention strategies.
- The role of glucose metabolism and insulin response in CVD pathogenesis requires further elucidation.
Purpose of the Study:
- To investigate the association between baseline one-hour post-oral glucose load serum insulin and blood sugar levels with the incidence of coronary heart disease (CHD) and cardiovascular mortality.
- To determine if these metabolic markers predict cardiovascular risk independently of established risk factors.
- To examine potential age- and sex-specific differences in the relationship between insulin, glucose, and cardiovascular outcomes.
Main Methods:
- A population-based cohort study in Busselton, Australia, initiated in 1966.
- Measurement of blood sugar and serum insulin levels one hour after an oral glucose load.
- Assessment of conventional cardiovascular risk factors at baseline.
- Follow-up for six-year incidence of CHD and 12-year mortality from CHD and all cardiovascular diseases.
- Calculation of risk ratios using upper 20th percentile values for baseline variables.
Main Results:
- In men aged 60-69, elevated one-hour serum insulin was strongly associated with increased CHD incidence and cardiovascular mortality (risk ratios 2.0-2.4).
- This association between higher serum insulin and cardiovascular mortality persisted in men of all ages and appeared independent of other major risk factors.
- Elevated blood pressure and serum cholesterol were significant predictors in younger subjects (<60 yr).
- A noticeable association between very high blood sugar (≥200 mg/100 ml) and cardiovascular endpoints was observed in individuals aged 60 and over (risk ratios 2.2-2.6).
- No significant association between serum insulin and CHD or cardiovascular disease was found in females.
Conclusions:
- Elevated one-hour serum insulin levels are a significant predictor of coronary heart disease incidence and cardiovascular mortality in middle-aged and older men.
- Serum insulin may represent an independent cardiovascular risk factor, particularly in males.
- The findings highlight the importance of considering glucose metabolism and insulin dynamics in cardiovascular risk assessment, especially in older male populations.
Abstract:
In the 1966 study of the population of Busselton, Australia, blood sugar and serum insulin levels were measured one hour after an oral glucose load, in addition to the conventional cardiovascular risk factors. The six-year incidence of coronary heart disease (CHD) and the 12-yr mortality from CHD and from all cardiovascular diseases is described in relation to the initial baseline variables measured using the upper 20th percentile values (age-specific and sex-specific) to define the risk ratios. In younger subjects (ages less than 60 yr), elevated blood pressure levels for both sexes (risk ratios from 2.9 to 5.2) and elevated serum cholesterol concentrations for males (risk ratios from 3.0 to 3.3) were strong predictors of cardiovascular risk. In men aged 60 to 69 yr, those with upper range one-hour serum insulin concentrations showed marked associations with the six-year incidence of CHD, the 12-yr mortality from CHD, and the 12-yr mortality from all cardiovascular diseases (risk ratios were 2.0, 2.3, and 2.4, respectively). The relationship of elevated serum insulin and cardiovascular mortality persisted when males of all ages were analyzed, and it appeared to be independent of the other major risk factors. In females, no association between serum insulin and CHD or cardiovascular disease could be found. Although the age and sex specific upper 20th percentile values for one-hour blood sugar concentrations showed a low grade association in patients with subsequent cardiovascular disease end points, more noticeable risk ratios were demonstrated at the higher blood sugar level of 200 mg/100 ml or greater (in the age group 60 yr and over, risk ratios were 2.2 in males and 2.6 in females.