Role of IGF binding protein-1 in the dawn phenomenon and glycemic control in children and adolescents with IDDM.
OBJECTIVE
To clarify the involvement of IGF binding protein (IGFBP)-1 in the dawn rise in plasma glucose and in the overall glycemic control in patients with IDDM.


METHODS
Seventy patients with IDDM were divided into three groups according to pubertal development. Blood samples were obtained for measuring plasma glucose, IGFBP-1, and free insulin at 2200, 0500, and 0700 over a 2-day period. Levels of HbA1c, IGF-1, and IGFBP-3 were determined at 0700. Urinary growth hormone (GH) was collected overnight. To examine its frequency, the dawn phenomenon was defined on the basis of the following: 1) change in plasma glucose from 0500 to 0700, 2) plasma glucose level at 0700, and 3) no antecedent hypoglycemia.


RESULTS
There was a statistically significant link between the dawn changes in plasma glucose and IGFBP-1 (r = 0.37, P < 0.01). The former was not related to the change in free insulin or to the overnight urinary GH level. In stepwise regression analyses, plasma glucose at 0700 = 0.03 IGFBP-1 (P < 0.01) + 0.525 HbA1c (P < 0.01) + 3.696 (R2 = 51%). Approximately half of the patients in each group exhibited the dawn phenomenon; 38% of patients with HbA1c < 8% also showed the dawn phenomenon.


CONCLUSIONS
We have demonstrated a statistically significant link between the morning risk in IGFBP-1 and plasma glucose. The free fraction of IGF-1 modulated by acute changes in IGFBP-1 may play a direct role. The dawn phenomenon may occur regardless of pubertal stage or glycemic control in children and adolescents with IDDM.
Kobayashi
K
K
Department of Pediatrics, Yamanashi Medical University, Japan.
Amemiya
S
S
Sawanobori
E
E
Higashida
K
K
Ishihara
T
T
Kobayashi
K
K
Kato
K
K
Nakazawa
S
S
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism*; D002648:Child; D002940:Circadian Rhythm; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood / Q000378:metabolism*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007564:Japan; D008297:Male; D011627:Puberty / Q000097:blood / Q000378:metabolism; D012016:Reference Values
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D006442:Glycated Hemoglobin; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I