Differences in umbilical cord insulin and birth weight in non-diabetic pregnancies of women from different ethnic groups in New Zealand

Abstract

SummaryMany ethnic groups at high risk of non-insulin-dependent diabetes mellitus are hyperinsulinaemic by early adult life. This study assessed whether such hyperinsulinaemia is present at birth. Cross sectional comparisons of maternal biochemistry, umbilical cord biochemistry and neonatal anthropometry were made between one 'low risk' and three 'high risk' ethnic groups, without diabetes in pregnancy in Auckland, New Zealand. The study comprised 123 European, Polynesian (Maori and Pacific Islands) and Indian normal pregnancies. Indian mothers were the smallest, with the highest insulin and non-esterified fatty acid concentrations. Polynesian mothers were the most obese with a higher fructosamine concentration. From these pregnancies, Indian neonates were smaller, slimmer, with the highest cord triglyceride (0.6mmol/I vs 0.4mmol/1, p <0.01), and lowest cord insulin concentrations (7.1 mU/1 vs 8.6 mUff (European), 9.2 mU/1 (Polynesian), p < 0.05). Polynesian babies had a high cord insulin: C-peptide ratio (52.5 mU/nmol vs 44.4 mU/ nmol (European), 44.1 mU/nmol (Indian), p = 0.05). Although reduced intrauterine growth may contribute to the excess of diabetes and heart disease in Indians, it cannot explain the excess of diabete s in Polynesians. Exposure to minor relative maternal hyperglycaemia in the mother and abnormal neonatal insulin handling (as demonstrated by the higher insulin: C-peptide ratio) may be of long-term significance in Polynesians. [Diabetologia (1994) 37: 930-936] Key words Insulin, C-peptide, fructosamine, triglyceride, birthweight, fatty acid, non-insulin-dependent diabetes mellitus.The pathogenesis of NIDDM remains obscure. Two risk factors which have been identified for future NIDDM diabetes are previous gestational diabetes [1] and belonging to certain ethnic groups [2]. In prospective studies, NIDDM is preceded by a moderate elevation in plasma glucose in spite of a high plasma insulin [3,4]. Non-diabetic relatives of NIDDM patients [5] and ethnic groups at high risk of NIDDM

Adiposity and Hyperinsulinemia in Indians Are Present at Birth

“…The difference between Indian and European babies disappeared when corrected for birth weight. The difference in the two studies may be due to exclusion in the New Zealand study of mothers and babies more likely to be insulin resistant (17).…”

Relationship between maternal glycaemia and birth weight in glucose‐tolerant women from different ethnic groups in New Zealand

“…At the time, we postulated an ‘obesity driven fuel mediated teratogenesis’. We have also previously found that compared with European and South Asians, babies from Polynesian glucose‐tolerant women have relatively higher umbilical cord insulin concentrations and insulin:C‐peptide ratio [16] and leptin concentrations [17]. At the time, the focus was on the maternal fuel supply as measured by plasma concentrations of glucose, non‐esterified fatty acids and triglycerides (the latter also being shown to be associated with larger babies [18]).…”