Diet, medication, and exercise are the three keys to controlling diabetes, the authors say, and too little attention has been paid to exercise. Far from sapping the diabetic's strength, regular workouts on the tennis court, in the swimming pool, or on the ski slopes will stimulate the body to more efficient use of glucose and may even lower the insulin-dependent patient's daily requirement. Aside from that immediate gain there are other rewards--a feeling of well-being, better weight control, improved heart rate, circulation, and so on. The authors interviewed 150 diabetic patients, including professional athletes like Bill Talbert and Ron Santo, all of whom described the positive results they had experienced with exercise. The authors caution against too much too soon, advise a thorough checkup before changing one's routine, and remind the patient that identification and emergency rations should always be at hand in case of an insulin shock emergency. They also describe the urine- and blood-sugar testing devices a patient can carry along. They point out, too, that there is still resistance to the idea of exercise from those who conceive of the diabetic as an invalid. The authors' spirited and often witty survey should do much to counter such resistance as well as inspire confidence in the more open-minded patient and his family.