dawn phenomenon

phenomenon /phe·nom·e·non/ (fĕ-nom´ĕ-non) pl. phenom´ena   any sign or objective symptom; an observable occurrence or fact.

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booster phenomenon  on a tuberculin test, an initial false-negative result due to a diminished amnestic response, becoming positive on subsequent testing.

dawn phenomenon  the early morning increase in plasma glucose concentration and thus insulin requirement in patients with type 1 diabetes mellitus.

Koebner's phenomenon  a cutaneous response seen in certain dermatoses, manifested by the appearance on uninvolved skin of lesions typical of the skin disease at the site of trauma, on scars, or at points where articles of clothing produce pressure.

Marcus Gunn's pupillary phenomenon  with unilateral optic nerve or retinal disease, a difference between the pupillary reflexes of the two eyes; on the affected side there is abnormally slight contraction or even dilatation of the pupil when a light is shone in the eye.

no-reflow phenomenon  when cerebral blood flow is restored following prolonged global cerebral ischemia, there is initial hyperemia followed by a gradual decline in perfusion until there is almost no blood flow.

Somogyi phenomenon  a rebound phenomenon occurring in diabetes: overtreatment with insulin induces hypoglycemia, thus initiating hormone release; this stimulates lipolysis, gluconeogenesis, and glycogenolysis, which in turn cause rebound hyperglycemia and ketosis.

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dawn phenomenon (dôn)

n.

The occurrence of abrupt increases in fasting levels of plasma glucose concentrations between the hours of 5 and 9 a.m., without preceding hypoglycemia, especially in diabetic patients receiving insulin therapy.

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dawn phenomenon

Etymology: ME, daunen + Gk, phainomenon, anything seen

a tendency for persons with type 1 diabetes mellitus to experience hyperglycemia upon awakening in the morning because of increased cortisol and growth hormone secretion in the predawn hours. Compare Somogyi effect (phenomenon).

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dawn phenomenon

Diabetology Early morning hyperglycemia not preceded by hypoglycemia, linked to ↑ insulin requirements in type 1 DM, possibly due to nocturnal pulses of hGH; DP also occurs in insulin-pump users receiving continuous subcutaneous insulin infusion, who are presumed to be euglycemic; DP is attributed to residual endogenous insulin or insulin-like molecules. Cf Somogyi phenomenon, Subcutaneous insulin resistance syndrome.