Diabetes Care, Vol 4, Issue 6 579-585, Copyright © 1981 by American Diabetes Association
The dawn phenomenon, an early morning glucose rise: implications for diabetic intraday blood glucose variation
MI Schmidt, A Hadji-Georgopoulos, M Rendell, S Margolis and A Kowarski
Eleven insulin-dependent (type I) diabetic subjects were studied during a
24-h period to assess intraday blood glucose (BG) variation and related
free insulin (FI) levels. Ten patients exhibited the dawn phenomenon, a
rise in early morning fasting blood glucose (123 +/- 81.1 m/dl; mean +/-
SD). This increase was positively and significantly correlated with the
morning postprandial BG peak (r = 0.723; P = 0.012). FI/BG ratios were
highest during the night (0.717 and 0.666 at 2200 and 0400 h, respectively)
and lowest during the early morning (0.294 at 0800 h) (P less than 0.01).
Three of the four observed hypoglycemic episodes occurred during the period
when free insulin levels were high relative to BG. We conclude that the
dawn phenomenon contributed directly and significantly to the BG maximum
and indirectly, in some cases, to nocturnal hypoglycemia. It thus played an
important role in the intraday blood glucose variation of such patients.