Diabetes and Coronary Plaque: How CT Scans Reveal Higher Plaque Burden in People with Diabetes

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Diabetes and Coronary Plaque: How CT Scans Reveal Higher Plaque Burden in People with Diabetes

If you have diabetes, you already know it raises your risk of heart problems—studies show your chance of a cardiac event (like a heart attack) is 2 to 3 times higher than someone without diabetes. But just how much does diabetes affect the plaque that clogs heart arteries? A 2020 study using advanced CT scans offers new insights: people with diabetes have significantly more and larger coronary plaques than those without the condition.

Why This Study Matters

Coronary plaque is a buildup of fat, cholesterol, and other substances in the walls of heart arteries. Over time, it narrows blood flow to the heart and can rupture—triggering blood clots that cause heart attacks. For years, doctors used coronary artery calcium (CAC) scoring to assess heart risk in diabetics, but this only measures hardened (calcified) plaque. Little was known about total plaque burden (including soft, dangerous types like lipid-rich plaque) in people with diabetes—until now.

Led by researchers from Fu Wai Hospital (Peking Union Medical College & Chinese Academy of Medical Sciences) and the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, the study used coronary CT angiography (CCTA)—a noninvasive scan that uses X-rays and contrast dye to visualize heart arteries—to quantify plaque in over 6,000 patients.

How They Did the Research

The team recruited 6,676 consecutive patients referred for CCTA by cardiologists between October 2016 and November 2017. They excluded people with incomplete data, poor image quality, or acute coronary syndrome (e.g., a recent heart attack), leaving 6,381 participants for analysis.

Key Methods:

  1. Plaque Measurement: Using CCTA scans, researchers classified plaque into three types—lipid (fatty, soft), fibrous (scar-like), and calcified (hardened)—based on Hounsfield units (HU) (a scale for X-ray density). Calcium was defined as at least three adjacent pixels with a density over 130 HU.
  2. Clinical Data: They collected information on traditional heart risk factors: age, sex, body mass index (BMI, with obesity defined as >30 kg/m²), hypertension (high blood pressure), high cholesterol, smoking, and family history of early heart disease.
  3. Ethics: The study was approved by Fu Wai Hospital’s Ethics Committee, and all patients gave informed consent.

What They Found

Of the 6,381 patients:

  • 14.5% had diabetes (931 people).
  • 48.3% of diabetics had coronary plaque—compared to just 33% of non-diabetics. This difference was statistically significant (meaning it wasn’t due to chance).
  • Diabetes was an independent risk factor for plaque: Even after adjusting for age, sex, smoking, and other risk factors, diabetics were 46% more likely to have plaque (odds ratio [OR] = 1.465, 95% confidence interval: 1.258–1.706).
  • Plaque volume was larger in diabetics: The total amount of plaque—including all three types—was significantly higher in people with diabetes. For example:
    • Lipid plaque (soft, dangerous): The middle 50% of volumes (interquartile range, IQR) was 25.2 mm³ in diabetics vs. 6.3 mm³ in non-diabetics.
    • Fibrous plaque (scar-like): IQR was 171.7 mm³ in diabetics vs. 73 mm³ in non-diabetics.
    • Calcified plaque (hardened): IQR was 5.3 mm³ in diabetics vs. 0.1 mm³ in non-diabetics.

What It Means for Diabetics

These results confirm a critical link: diabetes accelerates both the amount and type of plaque in heart arteries. For diabetics, this means their coronary arteries are more likely to have:

  • More plaque overall: Plaque burden (total volume) is a stronger predictor of future heart events than calcium scoring alone.
  • More dangerous plaque: Soft, lipid-rich plaques are especially risky because they can rupture easily, triggering clots that block blood flow to the heart.

The study also highlights the value of CCTA: Unlike older, invasive tests (like intravascular ultrasound, IVUS), CCTA is noninvasive and can study large groups—making it easier to track plaque in people with diabetes over time.

Limitations to Consider

No study is perfect. The researchers noted two key limitations:

  1. No glucose tolerance testing: They couldn’t rule out impaired glucose tolerance (a precursor to diabetes) in the non-diabetic group, as oral glucose tolerance tests weren’t done routinely.
  2. Diabetes duration: They didn’t account for how long participants had diabetes—an autopsy study found longer diabetes duration is linked to more severe atherosclerosis (plaque buildup).

The Bottom Line

For people with diabetes, this study underscores a vital message: regular heart screening is essential. CCTA can detect plaque early—even before symptoms like chest pain appear—allowing doctors to manage risk (e.g., with statins, blood pressure control, or lifestyle changes) and prevent life-threatening events.

The study’s lead authors—Zhi-Hui Hou, Bin Lu, and colleagues—concluded: “Coronary artery atherosclerotic plaques were significantly higher in diabetic patients than those in non-diabetic patients.” For diabetics, this is a reminder that managing blood sugar isn’t just about avoiding nerve damage or vision loss—it’s also about protecting your heart.

Original study: Hou ZH, Lu B, Li ZN, An YQ, Gao Y, Yin WH, Budoff MJ. Quantification of atherosclerotic plaque volume in coronary arteries by computed tomographic angiography in subjects with and without diabetes. Chinese Medical Journal 2020;133:773–778. doi: 10.1097/CM9.0000000000000733

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