This study has 3 major aims which are all designed to understand the mechanism that causes cognitive deterioration during mild hypoglycemia in children with IDDM and to assess a possible therapeutic strategy to prevent this cognitive deterioration. This study is also designed to verify the experimental insulin glucose clamp paradigm used to assess responses to hypoglycemia. The study will measure mental efficiency before, during and after an episode of mild and slightly more severe hypoglycemia of different durations. Counterregulatory hormones will be measured and blood will be drawn for measurement of glucose transporters on the red blood cells. In addition, estimations of "mental reserve" with a comprehensive neuropsychological test battery will be performed prior to the insulin glucose clamp. Assessment will be made of possible central neuropathy using auditory brain stem evoked potential. Lactate measures will be made during the induced hypoglycemia nad in Aim 2 the efficency of intravenous lactate in preventing hypoglycemia associated cognitive dysfunction will be evaluated.