Day-to-day variation of continuously monitored glycaemia: a further measure of diabetic instability.

Abstract

Differences between paired blood glucose values during two successive 24-h periods of continuous blood glucose analysis were investigated during 22 studies in seven unstable diabetics, three stable diabetics, and three normal subjects. The absolute means (without regard to sign) of daily differences (MODD) were high in unstable diabetics (36.6 to 158.1 mg/100 ml), intermediate in stable diabetics (10.2 to 35.1 mg/100 ml), and low in normals (6.2 to 8.2 mg/100 ml). MODD was a measure of the blood glucose changes resulting from day-to-day variation in response to therapy that was kept as constant as possible. When therapy was deliberately intensified through the use of four daily injections of short-acting insulin, MODD decreased in five of six such experiments. In two diabetics retested at intervals of 5 to 7 months without change in insulin regimen, MODD values remained similar. MODD quantifies another characteristic of blood glucose behaviour, the between-day variability; this is an important complement of the mean amplitude of glycaemic excursions (MAGE, a measure of within-day variability) and of the mean blood glucose concentration, MBG (the overall level of glycaemia during the variability measurements).