U-100 insulin gives some protection against metabolic deterioration due to CSII interruption.

We investigated the influence of insulin concentration within the insulin pump on the metabolic and plasma free-insulin changes induced by a 6-h nocturnal interruption of continuous subcutaneous insulin infusion (CSII) in five C-peptide-negative insulin-dependent diabetic patients with low circulating levels of anti-insulin antibodies. We compared the changes in blood glucose, plasma free fatty acids, 3-hydroxybutyrate, and free insulin during the interruption from 2300 to 0500 h of the Nordisk Infuser loaded with either U-100 or U-20 regular insulin. The decrease in plasma free-insulin levels was slower, resulting in a significantly delayed and smaller increase in blood glucose levels (2.4 +/- 1.6 vs. 7.6 +/- 2.9 mM, P less than .025) when the pump contained U-100 instead of U-20 insulin. Although the increases in levels of plasma free fatty acids were similar in both tests, the rise in plasma 3-hydroxybutyrate levels tended to be reduced with U-100 insulin (414 +/- 139 vs. 639 +/- 67 microM, P less than .10). Thus, our observations indicate that U-100 insulin gives some protection against the metabolic deterioration due to the interruption of CSII so that diabetic patients may be able to remain without the pump for longer periods with concentrated rather than diluted insulin.