The aim of the study was to examine nocturnal blood glucose profiles in Type 1 diabetic patients on multiple (greater than or equal to 4) daily insulin injections, Nocturnal blood glucose profiles were evaluated in 31 patients collecting blood samples half-hourly from 23.00 till 07.30 h, while they were asleep, Nocturnal episodes of hypoglycaemia (blood glucose <3.0 mmol l(-1)) occurred in 29% of these nights; 67% of episodes were asymptomatic. In the early night (23.00-01.00 h), five episodes occurred with a median duration of a h. In the early morning (04.00-07.30 h) seven episodes occurred with a median duration of 3 h. No hypoglycaemia was noted from 01.00 to 04.00 h. Bedtime glucose levels appeared to predict 'early night' hypoglycaemia but not 'early morning' hypoglycaemia; Fasting glucose levels <5.5 mmol l(-1) were indicative of preceding 'early morning' hypoglycaemia. There was a large intra-individual variation in nocturnal blood glucose profiles. It is concluded that daily monitoring of bedtime and fasting blood glucose levels may be both more reliable and convenient for the prevention of nocturnal hypoglycaemia than periodic testing of blood glucose at 03.00h as is often advised. Setting a target of >5.5 mmol l(-1) for fasting blood glucose may decrease the frequency of nocturnal hypoglycaemia.
