ORIGINAL ARTICLE

Intrauterine programming of urinary calcium and magnesium excretion in children born to mothers with insulin dependent diabetes mellitus

M Z Mughal¹, J A Eelloo¹, S A Roberts², S Sibartie¹, M Maresh³, C P Sibley⁴ and J E Adams⁵

¹ Department of Paediatric Medicine, St Mary’s Hospital for Women and Children, Manchester, UK
² Biostatistics Group, Division of Epidemiology and Health Sciences, University of Manchester, Manchester, UK
³ Department of Obstetrics and Gynaecology, St Mary’s Hospital for Women and Children
⁴ Academic Unit of Child Health, The Medical School, University of Manchester, St Mary’s Hospital for Women and Children
⁵ Clinical Radiology, Imaging Science and Biomedical Engineering, The Medical School, University of Manchester

Correspondence to:
Correspondence to:
Dr Mughal
Department of Paediatric Medicine, St Mary’s Hospital for Women and Children, Hathersage Road, Manchester M13 0JH, UK; zulf.mughal{at}cmmc.nhs.uk

Background: Offspring of diabetic rats have reduced urinary calcium and magnesium excretion compared with offspring of controls; these differences persist up to16 weeks after birth, a time equivalent to young adulthood in humans.

Objectives: To test the hypothesis that urinary calcium and magnesium excretion would be lower in children born to mothers with insulin dependent diabetes mellitus (ChMIDDM) than those born to non-diabetic mothers.

Methods: Concentrations of calcium, magnesium, sodium, and creatinine were measured in first void spot urine samples collected from 45 (28 male; median age 9.6 years) ChMIDDM and 127 (58 male; median age 11.3 years) controls. Analysis of covariance was used to test for differences in urinary calcium to creatinine ratios (UCa/Cr), magnesium to creatinine ratios (UMg/Cr), and log sodium to creatinine ratios (logUNa/Cr) between controls and ChMIDDM after allowing for the effects of sex and age.

Results: UCa/Cr (difference –0.10, 95% confidence interval (CI) –0.19 to –0.01; p = 0.03) and UMg/Cr (difference –0.15, 95% CI –0.22 to –0.08; p<0.0001) were lower in ChMIDDM than controls. However, logUNa/Cr did not differ between ChMIDDM and controls (difference –0.14, 95% CI –0.33 to 0.05; p = 0.1). The daily estimated intake of magnesium, sodium, and protein were significantly higher and that of calcium non-significantly higher in ChMIDDM than controls. In ChMIDDM, UCa/Cr and UMg/Cr were not related to diabetic control of mothers.

Conclusions: Results of this study provide the first evidence that in humans, as in rats, there is modification of renal Ca and Mg handling in ChMIDDM, which persists well into childhood.

Abbreviations: ChMIDDM, children born to mothers with insulin dependent diabetes mellitus; Cr, creatinine; HbA_1c, haemoglobin A_1c; IDDM, insulin dependent diabetes mellitus; SDS, standard deviation scores; UCa/Cr, urinary calcium to creatinine ratio; UMg/Cr, urinary magnesium to creatinine ratio; UNa/Cr, urinary sodium to creatinine ratio

Keywords: pregnancy; diabetes mellitus; urine; minerals; kidney

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