Diabetes and the rest of the body: a clear overview

Key points#

• Diabetes can affect small blood vessels (eyes, kidneys, nerves) and large ones (heart, brain, legs), and the feet are a special area where nerve and circulation changes meet.
• These complications are more likely after years of high blood sugar, but they are not inevitable.
• Strong trial evidence shows that better blood sugar, blood pressure, and cholesterol control meaningfully lowers the risk.
• A handful of routine checks, the eye exam, kidney tests, foot exams, and blood pressure, are built to catch problems early.

Diabetes is sometimes described as a blood sugar problem, which is true but incomplete. Over time, it is really a blood vessel and nerve condition, and that is why it can touch so many parts of the body. The point of mapping out where it can reach is not to frighten anyone. It is the opposite. Knowing the territory is what lets you, and your care team, stay ahead of it, and the evidence that you can is strong.

The small blood vessels#

High blood sugar over years can damage the body's smallest vessels. Three areas are watched closely.

• The eyes (retinopathy). The retina is rich in tiny vessels, and they are vulnerable to sustained high glucose. This is why a regular eye examination is part of diabetes care, since early changes can be found and treated before they affect sight.
• The kidneys (nephropathy). The kidneys filter blood through delicate vessels. Damage often shows up first as small amounts of protein in the urine, which is why periodic urine and blood tests are used to catch it early.
• The nerves (neuropathy). Nerve fibers, especially the long ones reaching the feet, can be affected, leading to numbness, tingling, or pain. Reduced sensation is part of why foot care becomes important.

The large blood vessels#

Diabetes also raises the risk of disease in the larger arteries, which contributes to heart attacks, strokes, and reduced circulation in the legs. This is why diabetes care is never only about glucose. Blood pressure and cholesterol get just as much attention, because they are central to protecting the heart and the circulation.

Why the feet get special attention#

The feet deserve their own mention because two of the problems above can meet there. If nerve changes dull sensation, a blister, cut, or rubbing shoe may go unnoticed. If circulation is also reduced, that small injury can be slow to heal. Caught early, these are minor. Left unnoticed, they can become serious. That is the entire reason clinicians ask about feet, look at them, and encourage daily checks and well-fitting shoes. It is simple, and it works.

The reason for optimism#

It would be easy to read all of this as a list of things to dread. The evidence points the other way. Two landmark studies make the case clearly. The DCCT in type 1 diabetes (PMID 8366922) and the UKPDS in type 2 diabetes (PMID 9742976) both showed that better blood sugar control reduced the risk of small-vessel complications, and the UKPDS also showed the value of controlling blood pressure. In other words, the everyday work of diabetes care, steady glucose, managed blood pressure, attention to cholesterol, and regular checks, genuinely changes the odds.

Staying ahead of complications#

Think of diabetes care as coordination rather than a single number. No one measurement tells the whole story, so the routine checks fit together: the yearly eye exam, the kidney tests, the foot exam, the blood pressure reading, the cholesterol check. Each is a small early-warning system. Keeping them on the calendar, and keeping the same care team in the loop over time, is how most complications are avoided or caught early. The body-wide reach of diabetes sounds daunting, but it is also exactly why consistent, unglamorous care pays off so well.