To study the prevalence and determinants of glucose intolerance in a general Caucasian population. A random sample of 50- to 74-year old Caucasians (n = 2,484) underwent oral glucose tolerance tests. Multiple regression analyses were performed to study the association of 2-h postload plasma glucose values with potential determinants. Prevalence of known and newly detected diabetes and impaired glucose tolerance was 3.6, 4.8, and 10.3%, respectively. In women, but not in men, the association of body mass index with 2-h glucose was fully accounted for by the waist-to-hip ratio. Maternal history of diabetes was twice as prevalent as paternal history, but paternal history only was associated with 2-h glucose. In addition, paternal history was a stronger determinant in men than in women. An independent positive association with 2-h plasma glucose was found for alcohol use of > 30 g/day in women and for intake of total protein, animal protein, and polyunsaturated fatty acids in men. An independent inverse association with 2-h plasma glucose was demonstrated for height (both sexes), alcohol use of < or = 30 g/day (both sexes), energy intake (in men), and, unexpectedly, current smoking (in men). The prevalence of diabetes in elderly Caucasians was 8.3%. In men, dietary habits may unfavorably influence glucose tolerance independent of obesity.