Glycosylated hemoglobin A₁c (HbA₁c) was measured as a marker for impaired glucose metabolism in a population survey performed in a farming community, Tanushimaru. Subjects were 1084 males and 1083 females aged over 40 who participated in this population survey in 1989.
Subjects were divided into two groups according to HbA₁c level (HbA₁c≤6.0 versus HbA₁c>6.0). The prevalence of cardiovascular risk factors in each HbA₁c group was analyzed by age and sex.
The results were as follows ;
1) In both men and women, obesity (BMI≥26) was significantly more frequent in the “high” HbA₁c group (HbA₁c>6.0).
2) In men, frequency of hypertension (systolic blood pressure over 160mmHg and/or diastolic blood pressure over 95mmHg) were significantly higher in the “high” HbA₁c group.
3) In women, hypercholesterolemia (T. cho≥220mg/dl) were significantly more frequent in the “high” HbA₁c group.
Clinically, it has been well known that impaired glucose metabolism is closely associated with cardiovascular risk factors. From the analysis of this field survey data, it was concluded that a high prevalence of various cardiovascular risk factors was present in the “high” HbA₁c group. Hypertension in men and hypercholesterolemia in women, in particular, showed high relative risks even after adjustment for age.

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This study performed in a manufacturing plant in Toyama prefecture, consisted of two parts. First, results of health examinations for cardiovascular diseases of 1980 and 1989 among industrial workers were compared between occupational categories. Second, the renults from a questionnaire surveying life style, such as dietary habit, carried out in 1990 were compared between occupational categories.
Subjects were 461 males aged 35-44 years old in 1980 who were examined in both 1980 and 1989. They were classified into four categories by their occupation in 1990- “managerial officer”, “special technician and clerical worker”, “light or medium, physical intensity laborer”, and “heavy physical intensity laborer”.
1. In 1989, significant differences between occupational categories and proportions of borderline blood pressure or hypertension were observed, despite no differences seen in 1980. Among those classified as managerial officers increased from 13.3% in 1980 to 33.4% in 1989, a prevalence that was significantly higher than the other groups.
In 1989, levels of serum cholesterol, β-lipoprotein and triglyceride were highest in the managerial officer group and lowest in the high physical intensity laborer group levels being almost identical between the groups in 1980.
2. Comparing dietary habits between occupational categories, the intake frequencies of main protein-rich food such as egg, meat and fish were lower in the managerial officer group and specialized technician and clerical worker group than the two laborer groups.The intake of cereals was lower in the managerial officer group also.
Other items of life style such as alcohol intake, smoking, sleep and exercise showed no difference between occupational categories.
These results suggest that occupation influenced the results of health examinations for cardiovascular diseases through unknown factors. Though the difference of life style such as dietary habit was suspected as one of those factors, the analysis of the results from the questionnaire of dietary habit and other lifestyle did not support the hypothesis.

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Levels of serum lipids and apoproteins by sex and age and their relationship to hypertension were studied in 916 participants (male 369, female 547) in a medical examination for the inhabitants of a rural area of Hokkaido Prefecture, Japan, conducted in 1989. Sex and age differences of serum lipids including apoproteins were noted, and comparison between groups with and without hypertension (diastolic pressure≥90mmHg) were performed. The hypertensive group consisted of 97 males and 136 females. In females hypertensives showed siginificantly higher levels of triglyceride ; apoprotein A-II, B, C-II, C-III and E ; than the normotensive group ; while there were no differences seen in males. Stepwise multiple regression analysis with the independent varibles of sex, age, smoking, drinking, obesity, triglyceride and apoprotein showed that sex, age, obesity, triglyceride and apoprotein were significantly related to blood pressure.

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A total of 2, 164 unselected consecutive clinical cases with essential hypertension who had been almost continuously treated with available depressor agents were followed for 30 years or until death. About 90% of the initial cases were successfully followed to the end of the study.
Twenty-one factors generally considered as risk factors of hypertension were subjected to multiple regression analysis to determine prognostic factors. This analysis demonstrated that initially noted obesity was an indepeddent predictor of long-term survival. Furthermore, survival rates of thin patients were relatively lower than those of other patients.
These results suggest that it is not necessarily appropriate to advise hypertensive patients who are slightly to moderately overweight to lose weight.

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In order to understand trends in circulatory diseases. Changes in health status levels of a factory worker population were studied. Health status levels used were “normal”, “moderately abnormal” and “treatment required”. The cohort was comprised of 3, 644 printing or paper manufacturingworkers who had complete records of annual health examinations from 1980 to 1990.
The group was divided into 7 birth cohorts with the birth-year range being 5 years, and the change of health statuslevel was observed. Studied were blood pressure, urine test, lipid metabolism, liver function, diabetes mellitus, heart disease and overall evaluation for disease.
Blood pressure abnormality increased with age and this relation closely followed Gompertz' law. Birth year appeared not to contribute to blood pressure. Nevertheless, the later the birth year, the number of “treatment required” subjects was less for workers with birh years between 1930 and 1940. The later the birth year, the greater number of “moderate blood pressure abnormality” subjects were observed among those who were born in 1941 or later and who were 45 years of age or younger.
For blood lipids and liver function, later birth cohorts experienced an increase in numbers of “moderately abnormal” subjects in younger ages than earlier birth cohorts. Among specific items, triglyceride and gamma -GTP abnormality were the dominant abnormalities.
Also, later birth cohorts experienced on increase in numbers of “treatment required” subjects of younger ages with the proportion of the “treatment required” group reaching 10 % in the younger ages, and stablising there after. Among workers with birth years between 1930 and 1935. the later birth cohorts have a higher proportion in the “treatment for heart disease required” group, while later birth cohorts have a lower proportion among the workers who were born in 1936 or later.

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All cases of stroke and acute myocardial infarction (AMI) occurring between April 1, 1988 to March 31, 1991 were registered for all residents of Okinawa prefecture. There were 4756 stroke and 1059 AMI cases during the period, for a crude annual incidence rate, per 100, 000 population aged 40 years or older, of 337 for stroke and 76 for AMI. The age-adjusted annual incidence of stroke tended to be higher in agricultural-fishery areas than commercial-industrial areas. For AMI, commercial-industrial areas tended to be higher. The incidence of cerebral hemorrhage was significantly higher in the agricultural-fishery areas than in the other areas. Ratios of stroke/AMI were 4.1 in commercial-industrial areas, and 5.0 in agricultural-fishery areas. For cerebral infarction/cerebral hemorrhage, ratios were 1.6 for commercial-industrial, and 1.3 for agricultural-fishery.
These results indicate an environmental variation in the incidence of stroke and AMI.

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