The investigation of dawn phenomenon in patients with insulin-dependent diabetes and normal subjects

Dawn phenomenon was investigated in 10 patients with insulin-dependent diabetes（IDDM） and 10 normal subjects. BG, GG, GH, F and ACTH levels were determined hourly during the peroid from 2400 to 0800 in all subjects, INS determined in the normal subjects. The results showed that a tendency of BG increase between 0500 to 0800 was present in 9 of 10 cases of IDDM, 8 of 10 normal subjects, but only in 8 cases of IDDM their BG increased markedly＞=2.5mmol/L （P＜0.01）. In the other cases the BG increases by less than I mmol/l（P＜0.05）. It suggested that the dawn phenomenon （increase value of BG in early morning more than I mmol/1） was found only in IDDM（80%）. We conclude that the pathogenesis of dawn phenomenon in IDDM may be related to oversecretion of F, GH and GG secondery to intracellular hypoglucemia due to lack of insulin.