How do you define "minor"? These insulins have dramatically different serum half lives (for example there are fast acting ones for postprandial administration, others that are optimized for pumps, etc) and so there is a clear pharmacological difference. Moreover, discovering these variants is nontrivial, as each insulin must be checked against igf-1 receptor cross reactivity, lest it become teratogenic. Making matters worse, the exact binding of insulin and igf-1 to their receptors is not known making this endeavor especially difficult to predict.

What is not clear is whether these modifications are an over optimization over "the original". For each patient the cost/benefit calculation will be different and based on many variables.