Diabetes and Heart Surgery: Why Bypass Is Often Preferred Over Stents

A different disease, not just more of it

Diabetes does not simply increase the likelihood of coronary artery disease. It changes its character. Understanding that difference explains why the treatment recommendation for a diabetic patient often differs from that for someone else with an apparently similar angiogram.

How coronary disease differs in diabetes

  • Diffuse rather than focal. Instead of one or two discrete narrowings in an otherwise healthy vessel, disease tends to involve long segments and multiple arteries, often extending into smaller distal branches.
  • Small vessel involvement. The microcirculation is affected as well as the large arteries, which limits how much any treatment aimed at the large vessels can achieve.
  • More rapid progression, and a higher burden of disease at the time of first presentation.
  • More silent. Diabetic neuropathy can blunt the perception of cardiac pain.

Silent ischaemia — the most practical point for patients

This deserves emphasis because it changes what a patient should watch for.

Angina is a warning signal carried by nerves. When those nerves are damaged by long-standing diabetes, the warning can be muted or absent. A diabetic patient may have significant coronary disease — even a heart attack — with little or no classic chest pain.

What to watch for instead:

  • Unexplained breathlessness on exertion, where previously there was none;
  • Unusual fatigue with ordinary activity;
  • Nausea, sweating, or a vague sense of unease during exertion;
  • Discomfort in the jaw, neck, arm, back or upper abdomen rather than the chest;
  • Sudden deterioration in blood glucose control without another explanation.

A diabetic patient who becomes breathless climbing stairs they managed easily last year should be assessed, even with no chest pain at all. See also chest pain: when to worry.

Why bypass often outperforms stenting in diabetes

For patients with diabetes and multivessel coronary disease, the evidence consistently favours bypass surgery over stenting, with better long-term survival and fewer repeat procedures.

The mechanism is worth understanding rather than taking on trust. A stent treats one point in an artery. In diffuse disease, treating that point leaves the rest of the diseased segment untouched, and disease progresses around and beyond it. A bypass graft, by contrast, is attached beyond the diseased segment and delivers blood to the whole territory downstream — it bypasses not only the lesion treated but future lesions in the segment it crosses.

Using arterial grafts, particularly the internal mammary artery, adds further durability, and multiple arterial grafting is often favoured in these patients for that reason.

This does not make stenting wrong in diabetes. For single-vessel or focal disease it remains appropriate. The decision belongs to a heart team reviewing the angiogram, and the pattern of disease matters more than the diagnosis label.

Surgery itself: what diabetes changes

  • Glucose control before surgery. Poor control raises infection risk substantially, particularly sternal wound infection. HbA1c is usually checked, and where the operation can safely be deferred, improving control beforehand is worthwhile.
  • Glucose control during and after surgery. Surgical stress raises blood glucose even in well-controlled patients, and insulin is frequently required temporarily — including in patients normally managed on tablets. This is expected and not a sign that diabetes has worsened permanently.
  • Wound healing and infection — the reason for meticulous wound care and early reporting of redness, discharge or fever.
  • Kidney function — diabetic kidney disease raises the risk of further impairment around surgery, and contrast studies are planned with that in mind.
  • Other vascular territories — carotid and peripheral arteries are more often affected, which is why they are assessed; see carotid disease and heart surgery.

After surgery

Diabetes continues to drive the disease process that caused the problem, so protecting the grafts means the same measures that protect the arteries: glucose control, intensive cholesterol lowering, blood pressure control, complete cessation of smoking, activity and weight management, and attendance at cardiac rehabilitation.

Some diabetes medications have established cardiovascular benefit, and treatment is often reviewed after cardiac surgery for that reason — a conversation worth having with your diabetes team rather than assuming your regimen stays fixed.

Further reading

MedlinePlus: diabetic heart disease, NHS: type 2 diabetes, and the WHO diabetes fact sheet.

General education, not advice about your own treatment. Do not change diabetes or cardiac medication without your treating team.