Comparison of plasma glucose and plasma free insulin during CSII and intensified conventional insulin therapy

The plasma glucose and plasma free insulin profiles of six totally insulin-dependent diabetic patients were compared during periods of 4 days in hospital under a conventional insulin therapy (ICIT) comprising 4 daily injections of regular insulin and under continuous subcutaneous insulin infusion (CSII). Two profiles of prandial insulin administration with CSII were compared: a rectangular (R) and an exponential wave (E) in which 50% of the dose was given rapidly followed by an exponential decrease. In both cases, the basal infusion rate was increased by 30-50% between 5 a.m. and 8 a.m. Mean circadian blood glucose was equally good with ICIT: R and E: 7.0 +/- 0.9, 7.3 +/- 1.0, and 7.1 +/- 1.0 mmol/L, respectively. In five patients, fasting plasma glucose was higher with ICIT than with R and E (12.7 +/- 1.8 versus 6.9 +/- 1.0 and 6.8 +/- 0.8 mmol/L, respectively; t test: P less than 0.05; Wilcoxon: P = 0.06). Mean plasma free insulin level was significantly higher (t test: P less than 0.005; Wilcoxon: P less than 0.05) with ICIT (0.46 +/- 0.04 nmol/L) than with R (0.37 +/- 0.04 nmol/L) or E (0.36 +/- 0.05 nmol/L), although the daily doses were similar. In conclusion, CSII leads to a better glycemic control than ICIT, since it appears to prevent the morning rise of blood glucose.