Type 2 diabetes roughly doubles the risk of coronary heart disease and stroke. The extra risk does not come from blood sugar alone. Diabetes usually arrives with higher blood pressure, a less favorable cholesterol pattern and strain on the kidneys, and each of these adds to the load on your arteries.
That also means the risk is not fixed. People with diabetes whose main risk factors are in range have much lower rates of heart attack and stroke than those whose factors are not. Knowing which numbers get checked, and why, is the place to start.
Key takeaways
- Having type 2 diabetes is linked to about twice the usual risk of coronary heart disease and stroke.
- The excess risk shrinks as blood sugar, blood pressure, LDL cholesterol, kidney markers and smoking are brought into range.
- A calcium score of zero is still good news in diabetes, but it holds for a shorter time than it does for other people.
- Kidney tests belong in a heart check because kidney strain and heart risk rise together.
How much does diabetes raise heart risk?
The clearest estimate comes from the Emerging Risk Factors Collaboration, which pooled individual records from 102 long-term studies. Among 698,782 people with no vascular disease at the start, diabetes was linked to twice the risk of coronary heart disease and slightly more than twice the risk of ischemic stroke, after accounting for age, sex, smoking, blood pressure and body mass index.1
The relative increase was larger in women than in men, and larger at ages 40 to 59 than at 70 and older.1 So diabetes matters most, in relative terms, in the groups who would otherwise expect lower risk.
Why blood sugar is only part of the story
High blood sugar over many years is hard on the lining of blood vessels. But type 2 diabetes is rarely a blood sugar problem alone. It usually develops on a background of insulin resistance, which tends to bring higher blood pressure, higher triglycerides, lower HDL cholesterol and more of the particles that carry cholesterol into artery walls.
Diabetes can also damage the kidneys over time, and reduced kidney function raises heart risk on its own. Our guide to kidney disease and heart risk explains that link.
This clustering is why a heart check in diabetes looks at several numbers together and not at A1c alone.
Risk varies a lot from one person to the next
Older advice treated diabetes as if it carried the same risk as already having heart disease. Studies since then show wide variation between individuals.
A Swedish registry study compared 271,174 people with type 2 diabetes with more than 1.3 million matched controls. It looked at five factors: A1c, LDL cholesterol, albumin in the urine (a sign of kidney strain), smoking and blood pressure. The excess risk fell step by step with each factor that was within its target range.2
People with diabetes who had all five factors in range had little or no excess risk of death, heart attack or stroke compared with the general population. One exception stood out: the risk of being hospitalized for heart failure stayed higher even then.2
This was an observational study, so it cannot prove that reaching each target is what lowered the risk. It does show that the word "diabetes" tells you much less than the full set of numbers.
Why a calcium score of zero is less reassuring in diabetes
A coronary artery calcium (CAC) scan looks for calcified plaque in the heart's arteries. For most adults, a score of zero points to low risk over the next several years.
The 2026 US cholesterol guideline says a zero can support holding off on cholesterol medication and rescanning in three to seven years, but it names diabetes as an exception, along with smoking, familial hypercholesterolemia and a strong family history.3
Follow-up data explain the caution. In the MESA study, researchers tracked 3,116 people who started with a score of zero and were rescanned over 10 years. Diabetes was associated with a significantly shorter time before calcium first appeared.4
None of this makes the scan useless in diabetes. In the same study population, calcium scores were independently linked to later heart events among the 881 participants with diabetes, and adding the score improved risk classification even when diabetes had been present for more than a decade.5
So a zero is still good news. It simply has a shorter shelf life, and it does not replace attention to the other numbers. Our guide to what a CAC score of zero means covers the general case.
What gets checked
| Check | Why it matters in diabetes |
|---|---|
| A1c | Reflects average blood sugar over recent months |
| Blood pressure | Often raised in diabetes and a major driver of heart attack and stroke |
| Lipid panel, sometimes with ApoB | Shows the cholesterol pattern and the number of plaque-forming particles |
| Kidney tests: eGFR and urine albumin | Kidney strain is both a complication of diabetes and a marker of heart risk |
| Smoking status | The strongest predictor of death in the Swedish study |
The same inputs feed the PREVENT risk equations now used in US guidelines. PREVENT counts diabetes and kidney function among its core predictors, and A1c and urine albumin can be added as optional inputs.6
Which tests you need, and how often, is for you and your clinician to decide. Do not start, stop or change a medication because of something you read here.
Your next step
If you have type 2 diabetes and have not had your heart risk reviewed as a whole, ask your clinician to go through the list above with you. Our guide to A1c and heart disease risk explains that number in more detail.
You can also answer the three quick questions in the screener on the Cardio Res-Q program page. A history of diabetes is among the risk factors listed on that page.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
Does everyone with diabetes develop heart disease?
No. Diabetes raises the odds, but the size of the increase depends heavily on blood pressure, cholesterol, kidney health, smoking and blood sugar itself. In a large Swedish registry study, people with type 2 diabetes who had all of these in range had rates of heart attack and stroke close to those of people without diabetes.
Is a calcium scan worth having if I have diabetes?
It can add information, because higher scores track with higher risk in people with diabetes just as they do in others. The limit is at the low end: a zero is less durable in diabetes, and guidelines do not treat it as a reason to relax. Whether a scan would change anything for you is a question for your clinician.
Is A1c the most important number for my heart?
It is one of several. In the Swedish study, an A1c outside the target range was the strongest predictor of heart attack and stroke among people with type 2 diabetes, but blood pressure, LDL cholesterol, urine albumin and smoking each added to the risk. Your own A1c target should be set with your clinician.
How is this different from prediabetes?
Prediabetes carries a much smaller increase in heart risk than diabetes, and the main goal at that stage is to stop blood sugar from rising further. We cover it in a separate guide, listed below.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
