INS and diabetes mellitus: Thus far, observational studies [6, 9] and randomized clinical trials [10–12] have found no compelling evidence of an increased breast cancer incidence in insulin-treated diabetes patients, although recently some studies have suggested a possible elevated risk with long-term insulin glargine use [5, 13, 14], which might be related to the more constant pharmacokinetic profile and enhanced IGF-1 receptor affinity of this insulin analog [15, 16].