Advancement Of Dawn Phenomenon

"dawn phenomenon"is a term used to describe hyperglycemia or an increase in the amount of insulin needed to maintain normoglycemia, occurring in the absence of antecedent hypoglycemia or poor control of blood glucose, during the early morning hours. According to recent study, type 1 and type 2 diabetes mellitus patients are identical in the frequency and magnitude of dawn phenomenon. General, a person could be diagnosed as"dawn phenomenon"whose blood glucose during dawn period is elevated by 5·1~12·2mmol/L than the overnight without routine basal insulin rate changing; or overnight blood glucose is stable but fasting hyperglycemia in 5~9 o'clock; or basal insulin rate increases by more than 50% in the early morning than the last night. The exact biochemical pathways of dawn phenomenon are unknown, and many hormones may be involved, such as growth hormone, glucocorticoid , glucagons, etc. At present, adjusting the type, amounts and time of insulin precisely is considered to be the feasible management, the best way is continuous subcutaneous insulin infusion (CSII); or increasing the dose of intermediate-acting insulins or long-acting insulins before sleeping; or regular insulin subcutaneous inject at 3:00 in the morning; or moving the insulin therapy from pre-breakfast to 6:00 in the morning, to shorten the time of hyperglycemia. Taking orally low dose dimethylbiguanide before sleeping can play an important role in relieving or eliminating the dawn phenomenon. Somatostatin or somatostatin receptor 2 agonist can inhibit the nocturnal secreting peak of growth hormone and glucagon, therefore avoid dawn phenomenon. It also works well to prescribe cyproheptadine for a patient with dawn phenomenon.