We studied the hypothesised effects of baseline levels of life satisfaction and of job satisfaction on the incidence of diabetes. Participants were 2,305 apparently healthy men and women who underwent routine health checks at two points in time, about 20 months apart. New cases of diabetes (N = 104) were defined based on fasting glucose value > 125, or glycosylated hemoglobin value > 6.5, or self-reported physician diagnosis of diabetes and taking medications to treat it. Life satisfaction was measured using the scale constructed by Diener et al. (1985) while job satisfaction was assessed based on the Survey of Working Conditions. In the analyses, we controlled for socio-demographic predictors, for known physiological and behavioral precursors of diabetes, and for depressive symptoms. There was support for our hypothesis that the higher the baseline levels of life satisfaction, the lower the incidence of diabetes. However, job satisfaction did not predict the incidence of diabetes. We obtained the same results when limiting the analysis to new cases of diabetes based on objective criteria only and when using as predictors both life and job satisfaction. We suggest that life satisfaction could be a protective factor reducing the risk of diabetes.