Need stable diabetics mix their insulins?

Ten insulin-dependent diabetics taking twice-daily mixtures of soluble and isophane insulin were studied in a double-blind crossover trial to examine the effect on their glycaemic control of a fixed-mixture preparation (containing either 50% soluble, 50% isophane or 30% soluble, 70% isophane) given in the same total dose as each patient's usual mixture. The mean (+/- S.E.M.) of eight daily blood glucose determinations when the patients' usual mixtures were pre-mixed by the hospital pharmacy was 7.6 +/- 0.7 mmol/l, 7.8 +/- 0.8 mmol/l when the fixed-mixture preparation was used and 8.0 +/- 0.5 mmol/l when the patients drew up and mixed the insulins themselves. Individual glucose profiles on each of the three regimens expressed as mean modified log 'M' indices were 1.26 +/- 0.14, 1.29 +/- 0.16 and 1.37 +/- 0.14, respectively. Thus, the patients studied were as well controlled on a fixed-mixture preparation as on their usual 'tailormade' insulin regimens.