Complex sentence: Milder forms have occasionally been detected by investigation of family members of infants with severe forms, adults with the mildest degrees of congenital hyperinsulinism may simply have a decreased tolerance for prolonged fasting.
Split into simpler sentences: Milder forms have occasionally been detected by investigation of family members of infants with severe forms. Adults with the mildest degrees of congenital hyperinsulinism may simply have a decreased tolerance for prolonged fasting.