Third Trimester Maternal Glucose Levels From Diurnal Profiles in Nondiabetic Pregnancies: Correlation With Sonographic Parameters of Fetal Growth: A response to Parretti et al. and Jovanovic

doi:10.2337/diacare.25.6.1104

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Letters: Comments and Responses
Letter

Third Trimester Maternal Glucose Levels From Diurnal Profiles in Nondiabetic Pregnancies: Correlation With Sonographic Parameters of Fetal Growth

A response to Parretti et al. and Jovanovic

Robert Fraser, MD, FRCOG

University of Sheffield, Sheffield, U.K.

Parretti et al. (1) report an important study in which diurnalprofiles performed on home blood-glucose monitoring were relatedto sonographic parameters of fetal growth. They imply in theirintroduction that the number of published studies concerningnormoglycemia in nondiabetic pregnancies are few, a point thatis also made by Jovanovic (2) in the accompanying editorialentitled "What is so bad about a big baby?"

Table 1 shows the diurnal plasma glucose profiles at 29 and35 weeks gestation on identical diets from the subjects of ourrandomized controlled trial of low and relatively high dietaryfiber diets given to women selected as being of normal weightand known to be nondiabetic (3). This study was published in1983. In the original publication, two arms of the trial containing12 and 13 subjects, respectively, were published separatelyfor comparative purposes but have been combined for the purposeof this letter. Meals were taken as follows: breakfast beforeadmission, midmorning snack at 1030 h, mid-day meal at 1200h, midafternoon snack at 1515 h, evening meal at 1730 h, andsupper at 2130 h. In these healthy women there was no deteriorationin glucose homeostasis between 29 and 35 weeks gestation whenstudied on identical test meals (3).

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Table 1— Diurnal plasma glucose profiles (mg/dl) at different gestational ages

In an earlier review (4) of factors possibly causative of macrosomiain the fetus of diabetic women, despite apparently good diabeticcontrol, I raised three hypotheses that might explain how glucosecould cause such an effect. The first hypothesis quoted Jovanovicet al. (5), stating that the postprandial glycemic peaks maybe particularly high in diabetic pregnancy. However, these peaksmay not be recorded on routine testing, a suggestion that hasreceived further support in a recent publication from the Northof England (6). The second hypothesis suggested that duringovernight fasting, minor variations of fasting glycemia mighthave a disproportionate effect on fetal insulinization and growth.We provided some evidence to support this hypothesis in ourown publication, again from nondiabetic women selected for bodyweight and studied in relation to fetal insulinization and neonatalanthropometry (7). This revealed a positive correlation betweenmaternal fasting glucose in the third trimester and birth weight.The third hypothesis to explain macrosomia, despite good controlin the diabetic mother, was that idiosyncracy might be operatingin terms of transplacental glucose kinetics in individual maternalfetal pairs with different rates of glucose transfer, despitesimilar maternal glycemic levels. This latter hypothesis remainsunder investigation in our laboratory.

Footnotes

Address correspondence to Robert Fraser, MD, FRCOG, AcademicUnit of Obstetrics and Gynaecology, The Jessop Wing, Tree RootWalk, Sheffield S10 2SF. E-mail: r.b.fraser{at}sheffield.ac.uk.

References

Parretti E, Mecacci F, Papini M, Cioni R, Carignani L, Mignosa M, La Torre P, Mello G: Third-trimester maternal glucose levels from diurnal profiles in nondiabetic pregnancies. Diabetes Care 24:1319–1323, 2001[Abstract/Free Full Text]
Jovanovic L: What is so bad about a big baby? Diabetes Care 24:1317–1318, 2001[Free Full Text]
Fraser RB, Ford FA, Milner RDG: A controlled trial of a high dietary fibre intake in pregnancy: effects on plasma glucose and insulin levels. Diabetologia 25:238–241, 1983[Medline]
Fraser R: Diabetic control in pregnancy and intrauterine growth of the fetus. Br J Obstet Gynaecol 102:275–277, 1995[Medline]
Jovanovic-Peterson L, Peterson CM, Reed GF, Metzger BE, Mills JL, Knopp RH, Aarons JH: Maternal postprandial glucose levels and infant birthweight: the Diabetes in Early Pregnancy Study: the National Institute of Child Health and Human Development-Diabetes in Early Pregnancy Study. Am J Obstet Gynecol 164:103–111, 1991[Medline]
Kyne-Grzebalski D, Wood L, Marshall SM, Taylor R: Episodic hyperglycaemia in pregnant women with well-controlled type 1 diabetes mellitus: a major potential factor underlying macrosomia. Diabet Med 16:702–706, 1999[Medline]
Soltani-K H, Bruce C, Fraser R B: Observational study of maternal anthropometry and fetal insulin. Arch Dis Child Fetal Neonatal Ed 81:F122–F124, 1999[Medline]