Received on June 14, 2005
Accepted on August 22, 2005

Endocrinology and Metabolism

Increased Plasma Pro-B-Type Natriuretic Peptide in Infants of Women with Type 1 Diabetes

¹ Departments of Clinical Biochemistry, Obstetrics, University of Copenhagen, Copenhagen, Denmark
² Department of Clinical Biochemistry, University of Copenhagen, Copenhagen, Denmark
³ Departments of Clinical Biochemistry, University of Copenhagen, Copenhagen, Denmark
⁴ Department of Obstetrics, University of Copenhagen, Copenhagen, Denmark
⁵ Department of Endocrinology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
⁶ Clinical Biochemistry, University of Copenhagen, Copenhagen, Denmark

^* To whom correspondence should be addressed. E-mail: Larsbo{at}rh.dk.

Background: Up to 40% of newborn infants of women with type 1 diabetes have echocardiographic signs of cardiomyopathy. Increased plasma concentrations of B-type natriuretic peptide (BNP) and its precursor (proBNP) are markers of cardiac failure and hypoxia in adults. In this study, we investigated whether plasma concentrations of proBNP and/or BNP are increased in infants of women with type 1 diabetes.

Methods: Plasma BNP and proBNP were measured with RIAs. The proBNP assay measures both intact proBNP and NH₂-terminal fragments derived from this precursor, whereas the BNP assay measures only BNP-32 and not proBNP.

Results: Infants of women with diabetes and hemoglobin A_1c (Hb A_1c) 6.2% before delivery had a higher median plasma proBNP concentration (31 pmol/L; interquartile range, 21-47 pmol/L; n = 16) than infants of healthy women [16 (9-32) pmol/L; n = 21; P = 0.01]. Infants of women with diabetes and Hb A_1c <6.2% (n = 15) had intermediate values. The plasma BNP and proBNP concentrations were closely associated (r² = 0.80; P <0.0001); within the group of infants of women with diabetes and Hb A_1c 6.2%, both correlated with the degree of fetal stress during labor.

Conclusions: Maternal diabetes and suboptimal metabolic control may affect the fetal heart and may predominantly stimulate proBNP secretion in conjunction with perinatal stress.