Diabetic hyperosmolar coma is characterized by the appearance of a diabetic metabolic state in middle age, lack of ketosis, osmolarity of the plasma greater than 350 milliosmoles, psychic and neurological disturbances, increased occurrence of secondary diseases, arterial thromboses, azotemia. The mortality is 30-60%. The pathogenesis is still uncertain in many respects, consequently the suggestions for therapy are varied. The authors have found the following procedure useful: rapid compensation of sodium deficit, restoration of water balance, normalization of the composition of body fluids by reference to continuous laboratory investigation.