The main causes of death in DM are heart disease and stroke. And long term sequelae can be prevented or delayed by keeping your blood sugar under control and managing other risk factors for heart disease.
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med school

Over time, elevated levels of sugar in the blood and poor circulation can harm the heart, brain, legs, eyes, kidneys, nerves, and skin, resulting in angina, heart failure, strokes, leg cramps on walking (claudication), poor vision, kidney failure, damage to nerves (neuropathy), and skin breakdown. Heart attacks and strokes are more common among people with diabetes.

Poor circulation to the skin can lead to ulcers and infections and causes wounds to heal slowly. People with diabetes are particularly likely to have ulcers and infections of the feet and legs. Too often, these wounds heal slowly or not at all, and amputation of the foot or part of the leg may be needed.

People with diabetes often develop bacterial and fungal infections, typically of the skin. When the levels of sugar in the blood are high, white blood cells cannot effectively fight infections. Any infection that develops tends to be more severe.

Damage to the blood vessels of the eye can cause loss of vision (diabetic retinopathy). Laser surgery can seal the leaking blood vessels of the eye and prevent permanent damage to the retina. Therefore, people with diabetes should have yearly eye examinations to check for damage.

The kidneys can malfunction, resulting in kidney failure that may require dialysis or kidney transplantation. Doctors usually check the urine of people with diabetes for abnormally high levels of protein (albumin), which is an early sign of kidney damage. At the earliest sign of kidney complications, people are often given angiotensin-converting enzyme (ACE) inhibitors, drugs that slow the progression of kidney damage.

Damage to nerves can manifest in several ways. If a single nerve malfunctions, an arm or leg may suddenly become weak. If the nerves to the hands, legs, and feet become damaged (diabetic polyneuropathy), sensation may become abnormal, and tingling or burning pain and weakness in the arms and legs may develop (see Peripheral Nerve Disorders: Causes). Damage to the nerves of the skin makes repeated injuries more likely because people cannot sense changes in pressure or temperature.
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Doctors in my experience do not take amputation lightly. It took me a while to find a doctor willing to do a revision on my stump, because they would rather salvage than take anything away.

If a knee replacement goes wrong it can result in a high AK amputation or even a hip disarticulation… which is no fun. Diabetics as a rule have harder healing times so his uncle may not have any other option at this point than amputation. It may have been an option earlier on but maybe it isn’t now.

My advice would be to ask his medical team lots of questions let them know your concerns and trust them.

Try contacting the Amputee Coalition of America They’re a great US run organization that can provide you with information on the surgery and prosthetics. They have a peer visitor program which may help your uncle and your whole family.

Amputation doesn’t have to be scary.
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