While both rapid-acting insulin analogs, aspart (Novolog) and lispro (Humalog), have been tested for safety and your pump user guide lists them as approved for use with the pump, more detailed studies of efficiency show differences. It’s not that you’ll have problems as such with either, but Novolg provides more stability and predictable action over time. My pump educator alerted me to that and I have certainly noticed the difference (including in amounts I needed to use to achieve the same results) during the periods when I had to switch.
Here are some of the studies I’ve read to this effect:
http://journals.aace.com/doi/abs/10.4158/EP10260.RA (“A series of chemical and covalent changes affecting the primary structure of an insulin preparation, however, may cause decomposition during storage, handling, and use, diminishing the potency of the insulin molecule while contained in an insulin pump. Precipitation, fibrillation, and occlusion may ensue, undermining compatibility for CSII pump use. Aspart has demonstrated the greatest chemical and physical stability in the insulin pump.”)
Precipitation of insulin products used for continuous subcutaneous insulin infusion - PubMed (Suggests why insulins that have similar action in the body when injected directly might differ when delivered via tubed pumps.)
Laboratory-based non-clinical comparison of occlusion rates using three rapid-acting insulin analogs in continuous subcutaneous insulin infusion catheters using low flow rates - PubMed (More along the same line of logic: occlusion rates over 5-day use significantly lower with aspart. “Over the whole of the 5-day infusion period, the probabilities of overall occlusion for each insulin were 40.9% [28 to 55%, 95% confidence interval (CI)] for glulisine, 9.2% (4 to 19.5%, 95% CI) for aspart, and 15.7% (8.1 to 28.1%, 95% CI) for lispro. All occlusions, except for three, occurred during a bolus infusion.”)
Better postprandial glucose stability during continuous subcutaneous infusion with insulin aspart compared with insulin lispro in patients with type 1 diabetes - PubMed (“Although both analogs resulted in similar daily blood glucose variability profiles and frequency of hypoglycemic episodes, postprandial glycemia was more stable with insulin aspart than with insulin lispro (absolute change in glucose 7.04 ± 3.16 versus 9.04 ± 4.2 mg/dl; p < .0019).”)
A randomized trial comparing continuous subcutaneous insulin infusion of insulin aspart versus insulin lispro in children and adolescents with type 1 diabetes - PubMed or full text here http://paperity.org/p/43024242/a-randomized-trial-comparing-continuous-subcutaneous-insulin-infusion-of-insulin-aspart (“Notably, the weight-adjusted mean daily dose of insulin aspart was significantly less than that of insulin lispro. Although subjects in the aspart group used less insulin, they were able to achieve comparable levels of glycemic control at the end of the study.” “Daily insulin dose (units per kilogram) was significantly lower at week 16 for subjects treated with aspart compared with those treated with lispro (0.86 +/- 0.237 vs. 0.94 +/- 0.233, P = 0.018).”)
Glycemic control after 6 days of insulin pump reservoir use in type 1 diabetes: results of double-blind and open-label cross-over trials of insulin lispro and insulin aspart - PubMed (Fewer unexplained highs for Novolog with 6-day use; fewer unexplained lows for Humalog. I guess what to do with this info mostly depends on what one’s personal greater issue is. For me it’s unexplained highs.)
This one compares Novolog and Apidra, but the reasoning why Novolog comes out better between the two is relevant for tubed usage:
http://online.liebertpub.com/doi/abs/10.1089/dia.2007.0233