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To study the effects on the fetus of variations in maternal glucose tolerance, a 25 g rapid intravenous glucose tolerance test was performed at or about 32 weeks gestation in 917 randomly selected nondiabetic women with singleton pregnancies. The results were withheld from the patients and their obstetricians and paediatricians, and no treatment or advice was offered. Fasting plasma glucose and indices of glucose disposal (including a new index which we have termed "summed glucose") were distributed unimodally, with no evidence of a separate pathological group towards the diabetic end of the distributions. Significant associations were found between maternal glucose metabolism and various measures of neonatal nutrition and morbidity, including the incidence of congenital malformations and morbidity related to asphyxia, suggesting that variations within the normal range in maternal glucose metabolism can influence growth and development in the fetus. These relationships were continuous throughout the range of maternal glucose tolerance and were not of predictive value in individual cases.

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A collaborative study compared methods for measuring glycosylated haemoglobin in seven laboratories in the United Kingdom. No satisfactory standard for general use was found. Satisfactory internal quality control systems were in use for each assay which allowed the maintenance of a normal range in each participating laboratory. No satisfactory quality control system suitable for general use could be identified. Costs and convenience of the assays are reported. The technical problems with each type of assay and precautions for their use were identified, such as the need for standardization in incubation times, the practicability of automation of colorimetric assays, and the precision of pH needed for buffers in column separation methods. The relevance of the technical problems to interpretation of measurements is also considered. It is concluded that laboratories measuring glycosylated haemoglobin should maintain a normal range, use 'in-house' quality controls to monitor assay performance and keep clinical colleagues informed of the findings and of any changes in methodology that might affect the interpretation of results.

No abstract