Donuts Not the Answer To the Editor: I was very glad to see Gregory Smith's article (1/89, p. 39) on blood sugar levels and job safety. The article bears out our personal research and experience in this area. Getting enough rest and maintaining a consistent level of blood sugar will insure the best possible performance in any area. His suggestions on how to do this, however, contain a major but common enough mistake. He suggests that coffee and sugary snacks are "high in energy" and will help you to maintain an even blood sugar level. This is not correct! Sugary snacks and coffee get into the blood stream very quickly. This indeed creates a burst of energy. Unfortunately the sense of