Oral glucose tolerance tests (OGTTs) with 75 g glucose were performed in 20 healthy pregnant Nigerian women in each trimester of pregnancy and the puerperium; 34 nonpregnant control subjects matched for age and parity were also studied. The blood glucose levels from fasting to 60 min were lower in pregnant subjects, but the 90- and 120-min values were higher. The highest blood glucose values were observed in the first trimester with an apparent improvement in glucose tolerance in the second and third trimesters. This observation is strikingly different from the established pattern of OCTT in pregnant Caucasian women. With pooled data from OGTT results in the three trimesters for the 20 pregnant women (60 OGTTs), a statistically derived criterion (based on mean + 2SD approximated to the nearest 5) for the interpretation of OGTT in pregnant Nigerian women was devised. This criterion defines the upper limits of normal for venous wholeblood glucose in pregnant Nigerian women during an OGTT with a 75-g glucose load as follows: fasting, 90; 30 min, 135; 60 min, 150; 90 min, 145; and 120 min, 125 mg/dl. These values are lower than those recommended for pregnant women by the National Diabetes Data Group (O'Sullivan and Mahan criteria) and the World Health Organization. The results from this study underscore the need for caution regarding uncritical application of data from one racial or ethnic group to others.

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