SPHK1 and diabetes mellitus: The development of treatment regimes to avoid complications arising from the presence of combined disease states, such as cancer and diabetes, is a major challenge: in this case, to balance cancer cell apoptosis and reduce disease complications whilst protecting pancreatic β-cell proliferation, it is becoming increasingly apparent that balancing the sphingosine rheostat is crucial in the development of many types of cancer and also diabetes; however, the opposing effects of SphK/S1P inhibitors on diabetes and cancer are a conundrum.