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The value of adding serum glucose assay to the ‘biochemical profile’ was assessed by a detailed follow-up of all inpatients with serum glucose concentrations of 10 mmol/l or more. After excluding patients who were on intravenous glucose infusions or were known to be diabetic. 1 in 10 was found to have unsuspected diabetes by further blood glucose measurements, glucose tolerance tests, and clinical assessment. The incidence was 0·8% of all inpatients receiving a biochemical profile, and in a full year 64 diabetics would be detected. The extra cost of laboratory tests was only £20 for each diabetic detected.

The diagnosis of gamma heavy-chain disease can be made only by immunochemical analysis of serum and urine. The case reported here demonstrates the importance of diligent observation of routine electrophoretic patterns, followed by immunoelectrophoresis where indicated for the identification of abnormal bands.

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 100% (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.