A total of 41 patients with hypertension were identified in a survey of 732 healthy factory workers. Twenty-three of these individuals were receiving antihypertensive medication, whereas 18 cases were newly discovered. Plasma glucose and insulin responses to oral glucose and fasting plasma triglyceride (TG), cholesterol, and high-density-lipoprotein (HDL) cholesterol concentrations of these 41 individuals were compared with those of 41 other factor workers, with normal blood pressure, matched with the hypertensive group in terms of gender, age, degree of obesity, job in the factory, and leisure-time activity. Patients with hypertension had significantly higher plasma glucose (P less than 0.05) and insulin (P less than 0.05) concentrations in response to oral glucose, as well as a higher plasma TG concentration (P less than 0.05). Similar findings were obtained when the treated and untreated hypertensive groups were analysed separately and compared with their respective control groups. However, there were no differences between the treated and untreated hypertensive groups. Ninety per cent of the normotensive group had a plasma insulin concentration of less than 500 pmol l-1 2 h after the glucose load. Using this value as the criterion for definition of hyperinsulinaemia, 41% of the patients with high blood pressure were hyperinsulinaemic. In addition to meeting this cut-off point, the patients with hypertension and hyperinsulinaemia were also glucose intolerant and dyslipidaemic. In conclusion, approximately 50% of an unselected group of patients with hypertension were hyperinsulinaemic. Insulin levels were comparable in treated and untreated patients with high blood pressure, and hyperinsulinaemic patients also tended to be glucose intolerant and dyslipidaemic.

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The effect of age on glucose tolerance, as differentiated from the effects of obesity, work and leisure physical activity, family history of diabetes, and the use of drugs known to adversely affect glucose tolerance and/or insulin secretion, has been analyzed in 732 factory workers aged 22 to 73 years. Glucose tolerance, as evaluated by the plasma glucose response to 75 g of oral glucose deteriorated with age, associated with an increase in plasma insulin levels. However, the age-related decrease in glucose tolerance also correlated significantly with degree of obesity, leisure-time physical activity, and the use of potential diabetogenic drugs. Partial correlation coefficients were calculated to define the effect of age per se on glucose tolerance, controlling for the presence of these other age-related variables. When this was done, the degree of correlation between age and glucose tolerance was reduced, particularly in women, to where it became of marginal statistical significance. The effect of age on insulin response was affected to a greater degree by age-related variables, and was no longer statistically significant when these other factors were taken into consideration. These data suggest that the elevation in plasma glucose and insulin levels associated with age are to a certain extent due to age-related environmental factors, and the deterioration in glucose tolerance with age is relatively modest in magnitude in a generally healthy population.

In people with type 2 diabetes, variations in the proportion of fat and carbohydrates of the diet, within the relatively narrow ranges recommended by different nutritional guidelines, significantly impact on the metabolic profile and markers of low-grade inflammation. The data support the potential for reducing the intake of fat and added sugars, preferring complex, slowly absorbable, carbohydrates.

The cluster of changes subsumed under the heading of syndrome X are closely associated with hyperinsulinaemia (and presumably insulin resistance), and can be discerned irrespective of degree of obesity.