Diabetes Care, Vol 16, Issue 12 1551-1556, Copyright © 1993 by American Diabetes Association
Prior feeding alters the response to the 50-g glucose challenge test in pregnancy. The Staub-Traugott effect revisited
GF Lewis, C McNally, JD Blackman, KS Polonsky and WM Barron
Department of Medicine, University of Chicago, Illinois.
OBJECTIVE--To examine the effect of prior meal ingestion on the glucose,
insulin, and C-peptide response to a 50-g glucose challenge test in the
third trimester of pregnancy. RESEARCH DESIGN AND METHODS--Ten pregnant
women with gestational diabetes mellitus and 12 nondiabetic pregnant
control subjects matched for age and weight underwent a 50-g glucose
challenge test on three occasions within a 2-wk period, in random order. On
one occasion the test was administered in the fasting state (fasting
glucose challenge test), on a second occasion the test was administered 1 h
after ingestion of a standard mixed meal (1-h postprandial study), and on a
third occasion the test was administered 2 h after ingestion of a standard
mixed meal (2-h postprandial study). RESULTS--In the control subjects, the
plasma glucose level 1 h after ingestion of 50 g of glucose was higher in
the fasting study (7.8 +/- 0.4 mM, 7 of 12 subjects with glucose > or =
7.8 mM) than in the 1-h postprandial study (6.7 +/- 0.3 mM, 3 of 12
subjects with glucose > or = 7.8 mM) and the 2-h postprandial study of
(6.3 +/- 0.4 mM, 3 of 12 with glucose > or = 7.8 mM) (P < 0.01). In
the postprandial studies of control subjects, insulin and C-peptide levels
were higher at the time of ingestion of the 50 g of glucose, but the early
(1 h) insulin secretory response was less than in the fasting study. In the
diabetic patients, glucose levels 1 h after 50-g glucose ingestion were
similar in the fasting study (10.5 +/- 0.4 mM, no subjects with glucose
value < 7.8 mM) and the 1-h postprandial study (11.0 +/- 0.6 mM, 1
subject with glucose < 7.8 mM), but was lower in the 2-h postprandial
study (9.3 +/- 0.3 mM, 1 subject with glucose < 7.8 mM) (P < 0.03).
In contrast to the control subjects, the insulin secretory response to 50 g
of oral glucose was greater in the two postprandial studies than in the
fasting study. CONCLUSIONS--We have reached the following conclusions. 1)
In nondiabetic gravidas, plasma glucose concentrations 1 h after ingestion
of a 50-g oral glucose load are higher if administered in the fasting state
compared with the postprandial state. 2) During normal pregnancy the
Staub-Traugott Effect, i.e., improved glucose disposal after successive
glucose load administrations, occurs and appears to be caused by mechanisms
other than enhanced insulin secretion with successive glucose loads. 3) The
effect of the prandial state on plasma glucose response to the 50-g glucose
challenge test used to screen for gestational diabetes mellitus may be of
sufficient magnitude to significantly alter the operating characteristics,
i.e., sensitivity and specificity, of this test.