INS and cancer: Telomerase reactivation is, however, contentious as it is also strongly associated with cancer (Akincilar et al., 2016), although mice derived from embryonic stem cells with extremely long telomeres showed better glucose and insulin tolerance and lower cancer risk than controls (Munoz-Lorente et al., 2019), suggesting that transient telomere lengthening strategies may improve health and avoid cancer risk.