A complicated explanation of diabetes in medicalese--only just redeemed by the simple, explicit exercise program. Cantu is, curiously, a neurosurgeon and a sports medicine specialist; his additional interest, in diabetes, came after his wife was diagnosed as having the disease. He makes two basic points: diet and exercise can prevent diabetes; exercise ""is critical to the management"" of the disease because it lowers blood sugar, controls weight, and improves general health. Cantu begins by discussing--shakily--the three-pronged treatment of diabetes with diet, exercise, and insulin: ""Diabetes is a condition characterized by a relative insulin deficiency resulting in an abnormal full-hormone response. . . ."" His description of ""The Metabolism of Insulin Use and Exercise"" is equally difficult to decipher (exercise seems to affect the body's sensitivity to insulin); but then things lighten up. Advice on choosing a physician to guide an exercise program pointedly asks ""is your doctor physically passive,"" or obese? Cantu's graded exercise regimens are not only detailed and safe, but complete with instructions on adjusting insulin dosage and administration. For those with a good background knowledge of their disease, then, a specific exercise regimen not found elsewhere. Others--seeking also the reasons to exercise--will find the June Biermann-Barbara Toohey Diabetic's Sports and Exercise Book (1976) a better introduction to the subject.