I've seen a show on TV that studied this question and they felt from his health records that he died from obesity and its complications - type 2 diabetes, high chloresterol, heart disease, gout, poor diet( meat, bread, baked goods),plain old overeating, high blood pressure, - plus infection from festering leg wound.
Most likely Syphilis. And Blood poisoning from his infected leg...
Probably a combination of untreated diabetes and syphilis
Henry the v111 died from being fat, smelling and a infected leg he needed a crane to pick up his coffin
Obesity and infection which caused Heart Disease