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SUMMARY.Fasting glycosylated haemoglobin was analysed in 535 consecutive patients having an oral 75 g glucose tolerance test for diagnostic purposes. A reference range for fasting glycosylated haemoglobin was established from patients with a non-diabetic glucose tolerance test as defined by the World Health Organisation Expert Committee on Diabetes Mellitus. The predictive value of a glycosylated haemoglobin of over 10·0% (mean normal + 3 SD) for detecting a diabetic glucose tolerance test was 89% but sensitivity was only 43%.A raised glycosylated haemoglobin is useful for confirming the diagnosis of diabetes mellitus in patients with long-standing hyperglycaemia but glycosylated haemoglobin is within the reference range in many patients with newly developed diabetes or other minor abnormalities of glucose tolerance. The glucose tolerance test must remain the test of choice in these patients.

The composition of serum seromucoid, the protein fraction of serum not precipitated by 0.6 M perchloric acid, has been shown to vary with the technique of preparation. Immunochemical examination revealed that 91.5% of the protein present in the seromucoid fraction of serum was alpha 1 acid glycoprotein, the remainder consisting of alpha 1 antitrypsin, alpha 1 antichymotrypsin, beta 2 glycoprotein, haemopexin, albumin, and pre-albumin. Serum alpha 1 acid glycoprotein concentration determined by radial immunodiffusion correlated well with serum seromucoid concentration although the former was usually 0.4 g/l lower. The determination of serum alpha 1 acid glycoprotein by an immunological method is more precise than the seromucoid method and is not subject to interference from other proteins.

Hourly measurements of bile acids, bacterial flora, and pH were made from gastric aspirates collected over 24 hours in subjects taking a controlled diet. Significantly higher concentrations of total bile acids were found following truncal vagotomy and antrectomy (TV+A), 2.73±1.16 SEM mmol/l, than after truncal vagotomy and pyloroplasty (TV+P), 0.88±0.56 mmol/l (p<0.002), and controls, 0.43±0.22 mmol/l (p<0.002). These observations were due to differences in nocturnal reflux only. Free secondary bile acids were identified more frequently after TV+A (19% of aspirates) than TV+P (6%) or controls (2%).Streptococcus faecalis andVeillonella spp, the principal organisms known to deconjugate and hydrolyze bile acids, were present in 65% of aspirates after TV+A compared with 35% after TV+P, and 33% of the controls. Mean pH values were 5.12 after TV+A, 2.82 after TV+P, and 2.14 in the controls. We conclude that antrectomy is associated with a greater incidence of duodenal reflux and a more suitable environment for the formation of secondary bile acids than vagotomy and pyloroplasty or in normal subjects.

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