Does sugar cause blood clots/plaque in the blood? If it does, by lowering sugar habit (eating a lot of sugar) will the blood thin?

Yes≈Complex! & No. Sugar intake ?es large HDL particles (µmol/l)+is converted by liver into triglyceride fat for storage {?es LDL (nmol/l) & body fat stores}. Other than low LDL particle numbers results in LDL particles entering artery walls, attracts monocytes/macrophages to eat/clear the LDL particles & without enough functioning HDL to unload the wbcs, they die & is called plaque. Plaque rupture induces clots.