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Although an increased plasma non-esterified fatty acid (NEFA) concentration has been shown to increase insulin resistance (Randle cycle), decrease insulin secretion and increase hepatic gluconeogenesis, the effect of NEFA on the deterioration of glucose tolerance has not been studied prospectively in Caucasian subjects. Therefore, we investigated whether plasma NEFA may be regarded as predictors of deterioration of glucose tolerance in subjects with normal (NGT, n = 3671) or impaired (IGT, n = 418) glucose tolerance who were participants in the Paris Prospective study. The subjects were first examined between 1967 and 1972 and underwent two 75-g oral glucose tolerance tests 2 years apart with measurements of plasma glucose, insulin and NEFA concentrations. Glucose tolerance deteriorated from NGT to IGT or non-insulin-dependent diabetes (NIDDM) in 177 subjects and from IGT to NIDDM in 32 subjects. In multivariate analysis, high fasting plasma NEFA in NGT subjects and high 2-h plasma NEFA and low 2-h plasma insulin concentrations in IGT subjects were significant independent predictors of deterioration along with older age, high fasting and 2-h plasma glucose concentrations and high iliac to thigh ratio. When subjects were divided by tertiles of plasma NEFA concentration at baseline, there was an increase in 2-h glucose concentration with increasing NEFA in the subjects who did not deteriorate, but no effect of plasma NEFA in those who deteriorated. In subjects with IGT who deteriorated compared with those who did not 2-h plasma insulin concentration was lower but there was no evidence that this resulted from an effect of plasma NEFA. Our data suggest that a high plasma NEFA concentration is a risk marker for deterioration of glucose tolerance independent of the insulin resistance or the insulin secretion defect that characterize subjects at risk for NIDDM.

The aim of this study was to compare the causes of death and parameters related to alcohol consumption, between subjects diagnosed as diabetic, clinically by their general practitioner, or glucose intolerant and in particular as diabetic, using the epidemiological criteria of an abnormal glucose level following an oral glucose tolerance test. The subjects in this study were 7035 working men, aged between 44 and 55 years, who attended the first follow-up examination of the Paris Prospective Study, between 1968 and 1973. They were classified as 'clinically diagnosed diabetic' or, following an oral glucose tolerance test and the World Health Organisation criteria, as having 'oral glucose tolerance test diagnosed diabetes', impaired glucose tolerance or normoglycaemia. The relative risk of death by cirrhosis, in comparison with the normoglycaemic group, was 21 (95% confidence interval: 9.1-49) in the group diagnosed diabetic by the oral glucose tolerance test, significantly different (p less than 0.02) from the group diagnosed diabetic clinically 3.1 (0.41-24); factors indicative of excessive alcohol consumption at baseline differed accordingly. In contrast, the relative risks for death by coronary heart disease were similar, 2.1 (1.0-4.1) and 2.7 (1.4-5.4) respectively; all of the factors defining the insulin resistance 'Syndrome X' (hyperglycaemia, hyperinsulinaemia, hypertension, hyperlipidaemia and also central obesity) and predictive of coronary heart disease were elevated in both groups of diabetic subjects. 'Diabetes', as diagnosed by the oral glucose tolerance test, might be the consequence of excessive alcohol consumption which could lead to insulin resistance, then to coronary heart disease, as well as to alcohol-related diseases.

The Paris Prospective Study is a long-term, large-scale study of the factors predicting coronary heart disease. The first follow-up examination included, for subjects not known as having diabetes mellitus, a 75 g oral glucose tolerance test with measurement of plasma insulin and glucose levels, fasting and 2 h post-load. Between 1968 and 1973, 6903 men aged 43-54 years were thus examined. Causes of death were ascertained within this group after 15 years of mean follow-up. The baseline variables were tested as predictors of death from coronary heart disease by a Cox regression analysis. Significant independent predictors of coronary heart disease death were: systolic blood pressure, number of cigarettes per day, plasma cholesterol level, and 2 h post-load plasma insulin level when entered as a categorical variable (below or above 452 pmol/l. i.e. the lower limit of the fifth quintile of the distribution). This dichotomization was performed to account for the non-linear univariate distribution of deaths with increasing post-load insulin values. Fasting plasma insulin level was not an independent predictor of death by coronary heart disease over this long-term follow-up. Levels of blood glucose were not significant independent predictors of death by coronary heart disease when plasma insulin levels were included in the model. The same applied to abnormalities of glucose tolerance when the 125 men with known non-insulin-treated diabetes at baseline were added to the group. Under the assumption that hyperinsulinaemia is a marker of insulin resistance, the results are consistent with the hypothesis that insulin resistance is associated with a higher risk of coronary heart disease mortality. However, it is doubtful that circulating insulin per se is a direct cause of arterial complications.

The Paris Prospective Study is a long-term investigation of the incidence of coronary heart disease in a large population of working men. The first follow-up examination involved 7,038 men, aged 43-54 years. Subjects with impaired glucose tolerance or diabetes (n = 943) were selected from the total population for a separate analysis of coronary heart disease mortality risk factors. During a mean follow-up of 11 years, 26 of these 943 subjects with abnormal glucose tolerance died from coronary heart disease. Univariate analysis showed that plasma triglyceride level (p less than 0.006), plasma cholesterol level (p less than 0.02), and plasma insulin level both fasting and 2-h post-glucose load (p less than 0.02), were significantly higher in subjects who died from coronary heart disease compared to those who did not. In multivariate regression analysis using the Cox model, plasma triglyceride level was the only factor positively and significantly associated with coronary death. The distribution of plasma triglyceride levels was clearly higher for the subjects who died from coronary heart disease compared to those who did not die from this cause or were alive at the end of the follow-up. This new epidemiological evidence that hypertriglyceridaemia is an important predictor of coronary heart disease mortality in subjects with impaired glucose tolerance or diabetes suggests a possible role of dyslipidaemia in the excessive occurrence of atherosclerotic vascular disease in this category of subjects.