Final answer:
Uncontrolled diabetes can lead to major complications such as stroke, blindness, and ulcers due to damage to small blood vessels from high blood glucose levels.
Step-by-step explanation:
The major complications mentioned, such as stroke, blindness, and ulcers, are closely associated with the long-term effects of uncontrolled diabetes. When diabetes is not properly managed, high blood levels of glucose can damage small blood vessels, which is a primary reason for these adverse outcomes. For example, damage to blood vessels in the retina can lead to vision loss and blindness, while similarly, damage to blood vessels in the brain can increase the risk of stroke. Additionally, diabetes can lead to diabetic neuropathy, which may cause foot ulcers that are difficult to heal and can sometimes result in severe complications requiring surgical intervention.