Which statements about the etiology and genetic risk for diabetes mellitus are correct?
1. Type 2 diabetes results from genetic susceptibility in addition to controllable risk factors.
2. Type 1 diabetes results from genetic susceptibility.
3. Viral infections may act as a trigger for type 1 diabetes.
4. Metabolic syndrome is a known cause for type 1 diabetes.
5. Pancreatic beta cells are destroyed in type 2 diabetes.