To ascertain the effects on blood glucose and plasma insulin levels of divided meals in diabetes, we measured both plasma levels in mild diabetic patients and in normal subjects after a breakfast. Division of the breakfast into two portions of standard composition separated by 30 min improved blood glucose levels in diabetic patients considerably, but division in which the first portion was high in protein produced a blood glucose response almost identical to that of normal subjects. Division of the meal into two balanced portions also improved the insulin response similarly for diabetic patients, but division in which the first portion was high in protein improved it so markedly that it brought the diabetic insulin response almost in line with the insulin response of the normal controls. We conclude, therefore, that the best meal for mild diabetic patients is a divided meal with the first portion containing as much protein as practicable.