Demonstration of a dawn phenomenon in normal human volunteers

• Published in: Diabetes (New York, N.Y.) Vol. 33; no. 12; pp. 1150 - 1153
• Main Authors: BOLLI, G. B, DE FEO, P, DE COSMO, S, PERRIELLO, G, VENTURA, M. M, CALCINARO, F, LOLLI, C, CAMPBELL, P, BRUNETTI, P, GERICH, J. E
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01.12.1984
• Subjects: Adult; Biological and medical sciences; Blood Glucose - physiology; C-Peptide - analysis; Circadian Rhythm; Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 2 - blood; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Epinephrine - blood; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Growth Hormone - blood; Homeostasis; Humans; Hydrocortisone - blood; Insulin - blood; Male; Medical sciences; Norepinephrine - blood; Epinephrine; Human; Glucagon; Steroid hormone; Secretion; STH; Use; Peptide hormone; Cortisol; Glucose; Circadian rhythm; Experimental study; Insulin; C-Peptide; Time dependent phenomenon; Protein hormone; Norepinephrine
• ISSN: 0012-1797; 1939-327X
• DOI: 10.2337/diab.33.12.1150

To ascertain whether the dawn phenomenon occurs in nondiabetic individuals and, if so, whether it is due to an increase in glucose production or a decrease in glucose utilization, we determined plasma concentrations of glucose, insulin, C-peptide, and counterregulatory hormones, as well as rates of glucose production, glucose utilization, and insulin secretion at one-half-hourly intervals between 1:00 and 9:00 a.m. in eight normal volunteers. After 5:30 a.m., plasma glucose, insulin, and C-peptide concentrations all increased significantly; rates of glucose production, glucose utilization, and insulin secretion also increased (all P less than 0.05). Plasma cortisol, epinephrine, and norepinephrine increased significantly from nocturnal nadirs between 4:00 and 6:30 a.m. Plasma growth hormone, which had increased episodically between 1:00 and 4:30 a.m., decreased thereafter nearly 50% (P less than 0.05). Plasma glucagon did not change significantly throughout the period of observation. These results indicate that a dawn-like phenomenon, initiated by an increase in glucose production, occurs in nondiabetic individuals. Thus, early morning increases in plasma glucose concentrations and insulin requirements observed in IDDM and NIDDM may be an exaggeration of a physiologic circadian variation in hepatic insulin sensitivity induced by antecedent changes in catecholamine and/or growth hormone secretion.