Let us focus on DMII. A lot of publications. Try to start with a review article. Helena von Bibra Curr Heart Fail Rep. 2016 Oct;13(5):219-229. Review or Diabetologia. 2010 Jun;53(6):1033-45.
The main confounder for diabetes II is overweight/obesity that is associated with LV remodelling/hypertrophy and diastolic dysfunction as well.
What starts first diastolic or systolic dysfunction. Well ask Ernande J Am Soc Echocardiogr. 2011 Nov;24(11):1268-1275.e1. doi: 10.1016/j.echo.2011.07.017.