Response to Fraser

In relation to our recent paper (1) on third trimester glucose levels in nondiabetic pregnant women, Dr. Fraser (2) reports some data on glucose profiles from nondiabetic nonobese pregnant women in the third trimester. We believe that these data are interesting first because there are few contributions on this topic and second because Dr. Fraser’s study relies on glucose profiles consisting of 17 determinations per day. However, there are some important differences in the two studies. Our study involved 51 pregnant women undergoing home glucose self-monitoring throughout the third trimester, whereas Dr. Fraser’s study relates to a smaller group of women who were hospitalized and investigated only at 29 and 35 weeks, therefore showing the same limiting factors (which were quoted in our manuscript) of all previous investigations on this subject.

In our study, we found a slight but progressive increase of glycemia throughout the third trimester, as assessed by comparing overall glucose values from glucose profiles between 28 and 38 weeks, whereas Dr. Fraser could not find any deterioration of glycemia during the third trimester. In this respect, it is noteworthy that, despite this trend of deterioration, the difference between overall glucose values at 28 and 38 weeks was not statistically significant in our study. Perhaps the failure to demonstrate deterioration in Dr. Fraser’s investigation arises from the shorter time period considered (6 weeks). In addition, if we look at overall glucose values found in our study group between 28 and 34 weeks or between 30 and 36 weeks, this tendency of deterioration is much less evident. A comparison between our results and Dr. Fraser’s findings is not possible because they used plasma glucose determinations, whereas we used blood glucose fingersticks. However, it seems that Dr. Fraser’s results somewhat support our findings by confirming that glycemia at the 1-h postprandial time point in the third trimester of pregnancy is well below the currently accepted thresholds for a tight metabolic control in diabetic pregnancy and does not exceed 105 mg/dl.

Regarding the issue of factors possibly causative of macrosomia in diabetic pregnancy despite good metabolic control, we believe, in agreement with Jovanovic (3), that “macrosomia despite normoglycemia” is often “macrosomia because of undetected hyperglycemia.” Actually, postprandial glycemic peaks can be very high in diabetic women and may not be identified on routine glucose monitoring, but our study, providing a true definition of normoglycemia in nondiabetic pregnancy, suggests an additional possibility, “macrosomia because of undertreated hyperglycemia.”