There's just not that much around in hard cover to help the diabetic patient or parent of a diabetic child let the sunshine into laboratory kitchens replete with scales and/or tables of equivalents. Euell Gibbons, with a number of distinctive cookbooks to his credit, invaded the galley of his diabetic brother Joe, diddled with ingredient exchanges and the all-important ""gram"" measure, came up with a system of converting standard recipes. It isn't really easy and it doesn't sound easy, but Mr. Gibbons has a way of prodding the reader to acquire the knack. There are sections on camping foods, jams and jellies (with the heavy use of pectin), freezing food, and a long treatise on the diabetic child. Throughout Mr. Gibbons insists on high-quality fresh foods, care, patience and imagination. There are also chapters concerning the demands of the disease and the importance of a healthy attitude. The use of calcium cyclamate tablets is somewhat controversial, but this material should of course be routinely checked by the doctor. However, these clever recipes could be immensely useful and cheering.