No sugar does NOT cause diabetes.
No sugar is not what causes diabetes.
Splenda is an artificial sweetener. It cannot prevent diabetes. Exercise, weight management, healthy lower carb minimally preceded food diet may help prevent development of Diabetes if you are genetically predisposed.
To the extent that the use of Splenda or other dietary adjustments prevent the gain of unhealthy body weight, such measures should reduce the likelihood of the onset of diabetes.