The present investigation examined effects of diets containing different proportions of macronutrients on longevity in two substrains of normotensive Wistar rats--Wistar Kyoto (WKY), the most widely accepted normotensive control for spontaneously hypertensive rats (SHR) and Munich Wistar rats (WAM as designated here). Each substrain was divided into five dietary groups composed of 15 rats each. Compared to a baseline diet composed of near equal calories of sucrose, fat, and protein, the remaining four diets were high sucrose-low protein, high sucrose-low fat, low sucrose-high protein, and low sucrose-high fat. Significantly higher systolic blood pressures were found in the two groups of WKY and WAM ingesting the high sucrose diets compared to the other three groups. The high sucrose groups were also hyperinsulinemic. Although only the group of WKY consuming the high sucrose-low fat diet showed a significantly shortened lifespan, the lifespan of WKY positively correlated with systolic blood pressure when data from all dietary groups were combined. WKY and WAM with an average systolic blood pressure exceeding 150 mm Hg had a significantly shorter lifespan than the rats with lower average blood pressure. Accordingly, elevated systolic blood pressure, especially when the blood pressure exceeds 150 mm Hg, significantly shortens lifespan.