If you’re living with Type 2 diabetes, there’s a good chance your heart is under more strain than you realize — and not just because of blood sugar. A silent nutrient shortfall is making that strain worse. Vitamin C plays a key role in protecting your arteries from damage, yet it’s one of the most commonly overlooked gaps in people with diabetes. Why? Because the warning signs are easy to miss.
There are no glaring symptoms at first, just subtle shifts like stiffer blood vessels, sluggish circulation and a greater chance of plaque building up where it shouldn’t. Over time, these changes raise your odds of heart attack, stroke and serious complications tied to narrowing of the arteries that often goes unnoticed until it’s already done real damage.
The real problem? Your body can’t make or store vitamin C. It has to come from what you eat, and processed foods and low fruit intake aren’t cutting it. That means many people are left unprotected at the cellular level, exactly when they need the most support. New research shows just how strongly this matters if you’re managing diabetes. Let’s take a closer look at what the science found.
Low Vitamin C Levels Linked to Artery Damage in People with Type 2 Diabetes
Research published in BMC Nutrition focused on 200 adults with Type 2 diabetes to find out whether low vitamin C levels had anything to do with heart disease risk.1 The researchers only included patients who hadn’t taken vitamin supplements for at least six months. They wanted to answer a straightforward but important question: If you’re not getting enough vitamin C from your food, are your arteries more likely to be damaged?
• People with lower vitamin C levels were more likely to have cardiovascular disease — On average, people without cardiovascular issues had vitamin C levels around 49.7 micromoles per liter, while those with cardiovascular damage averaged just 40.5. That’s a difference of nearly 20%, large enough to be statistically significant and biologically meaningful.
• The more severe the artery damage, the lower the vitamin C levels — The study found that individuals with greater narrowing of the arteries in the neck tended to have lower levels of vitamin C. In other words, the more advanced the vascular disease, the lower the vitamin C levels, which strengthens the case for a direct relationship between diet and vascular damage.
• Low vitamin C is also linked to higher triglycerides and lower “good” cholesterol — Researchers also found that those with vitamin C deficiency had lower levels of high-density lipoprotein (HDL) cholesterol (the kind that clears out artery-clogging fats) and higher triglycerides, a type of fat in your blood that raises heart risk.
The combination of low vitamin C, low HDL and high triglycerides is a dangerous trio that drives artery narrowing and increases your chances of a heart attack or stroke.
Diet, Lifestyle and Biological Clues Help Explain the Risk of Low Vitamin C
Food frequency questionnaires used in the study revealed that participants who ate fewer than one serving of fruit or vegetables per day had vitamin C levels as low as 28.7 micromoles per liter on average. But those who consumed more than two servings per day had significantly higher levels — nearly 50 micromoles per liter.2 That’s a 74% increase just from simple food changes.
• Vitamin C levels were worse in smokers and those with kidney problems — Smoking increases oxidative stress, which quickly depletes your body’s vitamin C reserves. And kidneys help regulate the antioxidant balance in your body, so any decline in their function affects how well you retain nutrients like vitamin C. If you have Type 2 diabetes and either of these additional risk factors, the need to monitor your vitamin C intake is even more urgent.
• Vitamin C works by protecting arteries from free radical damage — People with Type 2 diabetes produce more reactive oxygen species (ROS), which are unstable molecules that damage blood vessels over time. Vitamin C neutralizes these ROS before they harm artery walls. Without enough vitamin C, those harmful molecules remain active longer and start degrading the lining of your arteries, leading to plaque buildup.
• Vitamin C influences plaque formation by preserving nitric oxide and collagen — Beyond fighting free radicals, vitamin C plays a central role in preserving nitric oxide, a molecule that tells your blood vessels to relax and widen.3
Without nitric oxide, your vessels become stiff, narrow, and more prone to blockage. Vitamin C also supports collagen synthesis — meaning the structural integrity of your artery walls depends on it. If collagen is weak or broken down, your arteries lose their elasticity and become more prone to injury and inflammation.
Vitamin C Improves Blood Flow and Inflammation
In related research, a systematic review published in Frontiers in Nutrition explored how vitamin C supplements affected cardiovascular risk in people with Type 2 diabetes or metabolic syndrome.4 The researchers looked at 21 studies involving a total of 7,688 participants. All participants were adults with confirmed metabolic dysfunction and elevated risk for cardiovascular disease.
• Most trials showed that vitamin C supplementation at 1,000 milligrams (mg) per day helped reduce key risk markers — Participants showed reduced triglycerides and improved blood flow, for instance. These changes were particularly consistent in studies lasting four weeks to one year. Inflammation markers also dropped in many of the trials that measured them.
• Blood flow and artery flexibility improved in multiple studies — One of the most consistent findings was improved endothelial function, meaning the blood vessels became better at relaxing and expanding during circulation. This is a direct reflection of how healthy and responsive your vascular system is.
In people with diabetes, this function is often impaired. Vitamin C seemed to restore it in many participants, which helps reduce blood pressure and enhances oxygen delivery to tissues.
• Inflammation dropped quickly in the short-term trials — In several four-week trials, researchers documented lower levels of inflammatory markers just weeks after supplementation began. These markers are associated with vascular injury and plaque buildup, so their reduction signals that vitamin C helped calm the underlying inflammatory fire.
• The benefits were most consistent at 1,000 mg daily doses — Most of the successful trials used a standard dose of 500 mg taken twice daily or 1,000 mg taken once a day. Lower doses, such as 275 mg daily, were less effective in impacting blood pressure, cholesterol or inflammation. Trials lasting under four weeks also reported fewer changes, suggesting that a longer commitment is needed to see the full effects.
Whole Fruits Work for Heart Protection
An editorial published in the Indian Journal of Clinical Biochemistry explained how vitamin C-rich fruits help prevent coronary heart disease by optimizing blood cholesterol, vessel function and blood clotting.5
• The author emphasized food-based sources like amla, guava, lemon and orange — While vitamin C supplements have been linked to health benefits in some studies, others suggest whole foods are best. The editorial focused on the powerful effects of getting vitamin C from fresh fruits. Amla (also called Indian gooseberry) was noted to contain up to 600 mg of vitamin C per 100 grams, with oranges at 500 mg, guava at 242 mg and lemons at 50 mg.
• Vitamin C helps prevent dangerous blood clots in narrowed arteries — Blood clotting inside vessels — called thrombosis — is a common trigger for heart attacks. The author noted that vitamin C increased the blood’s fibrinolytic activity, or its ability to dissolve clots before they become deadly.
This mechanism is especially important for those already showing signs of arterial damage, as sudden clot formation is often the final straw that blocks blood flow and damages the heart muscle.
• Vitamin C also improves collagen production in blood vessels — When you don’t get enough vitamin C, your body can’t make strong collagen — the connective tissue that supports your arteries and keeps them flexible.6 Weak collagen means more cracks, inflammation and damage in your blood vessels, increasing the risk for plaque buildup and rupture. Getting enough vitamin C from food helps maintain your arterial integrity over time.
Simple Changes That Help Lower Heart Disease Risk in Type 2 Diabetes
If you’re dealing with Type 2 diabetes, there’s a high chance you’re also at increased risk for heart disease — and that risk climbs even faster when your diet is low in vitamin C from whole foods. Most people don’t realize this connection until it’s too late. I’m going to walk you through five practical steps to protect your heart and improve your metabolic health. If you’re tired of short-term fixes, start here.
You’ll want to address the root of the problem first — mitochondrial dysfunction and poor cellular energy, both of which worsen insulin resistance and damage your arteries over time. These steps are designed to help your cells do their job more efficiently so your blood vessels stay flexible, your cholesterol stays balanced and your heart gets the support it needs to last. Here’s where to begin:
1. Eat fresh fruits that are naturally high in vitamin C — Your body doesn’t produce vitamin C so you must get it from your diet. Don’t just sprinkle in a few berries now and then — commit to daily servings of fruit like guava, oranges, kiwi, grapefruit and lemon. Research shows vitamin C from fresh food has a direct inverse relationship with cardiovascular disease in people with Type 2 diabetes.7 That means the more you eat, the lower your risk.
2. Eliminate vegetable oils and processed foods from your diet — These oils, such as soybean, corn and sunflower, contain linoleic acid (LA), a type of polyunsaturated fat that damages your mitochondria and makes oxidative stress worse. You won’t get the benefits of vitamin C if your cells are drowning in this type of damage. Use grass fed butter, tallow or ghee instead. Skip the restaurant food and snack aisles. Your mitochondria need less interference, not more.
3. Rebuild your cellular energy with healthy carbohydrates — Glucose from carbs is what your mitochondria use to produce adenosine triphosphate (ATP) — your body’s primary energy currency. If your gut isn’t healthy, start with white rice and whole fruit. Gradually work your way up to root vegetables and starchy carbs like sweet potatoes. This is your fuel, and it’s the most efficient path toward healing oxidative stress at the source.
4. Track your metabolic health using the HOMA-IR test — Recognizing insulin resistance early is essential, as it’s a warning sign for your metabolic health — one that often precedes Type 2 diabetes.
The HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) test is a valuable diagnostic tool that helps assess insulin resistance through a simple blood test, so you can spot issues early and make necessary lifestyle changes, like eating more vitamin C-rich foods.
Created in 1985, it calculates the relationship between your fasting glucose and insulin levels to evaluate how effectively your body uses insulin. Unlike other more complex tests, HOMA-IR requires just one fasting blood sample, making it both practical and accessible. The HOMA-IR formula is as follows:
HOMA-IR = (Fasting Glucose x Fasting Insulin) / 405, where
• Fasting glucose is measured in mg/dL
• Fasting insulin is measured in μIU/mL (microinternational units per milliliter)
• 405 is a constant that normalizes the values
If you’re using mmol/L for glucose instead of mg/dL, the formula changes slightly:
HOMA-IR = (Fasting Glucose x Fasting Insulin) / 22.5, where
• Fasting glucose is measured in mmol/L
• Fasting insulin is measured in μIU/mL
• 22.5 is the normalizing factor for this unit of measurement
Anything below 1.0 is considered a healthy HOMA-IR score. If you’re above that, you’re considered insulin resistant. The higher your values, the greater your insulin resistance. Conversely, the lower your HOMA-IR score, the less insulin resistance you have, assuming you are not a Type 1 diabetic who makes no insulin.
Interestingly, my personal HOMA-IR score stands at a low 0.2. This low score is a testament to my body’s enhanced efficiency in burning fuel, a result of increased glucose availability. By incorporating additional carbohydrates into my diet, I provided my cells with the necessary energy to operate more effectively.
This improved cellular function has significantly boosted my metabolic health, demonstrating how strategic dietary adjustments lead to better insulin sensitivity and overall metabolic performance.
FAQs About Vitamin C and Heart Disease in Type 2 Diabetes
Q: What’s the link between vitamin C and heart disease in people with Type 2 diabetes?
A: Low vitamin C levels are strongly associated with a higher risk of cardiovascular disease in people with Type 2 diabetes. Research shows that vitamin C from whole foods helps lower inflammation, optimize cholesterol and support healthy blood vessels.
Q: How does eating whole fruit help protect your arteries if you have diabetes?
A: A 2025 study published in BMC Nutrition found that people with Type 2 diabetes who ate more fresh fruits and vegetables had significantly higher vitamin C levels — and fewer signs of artery damage.8 Those who ate the least had low vitamin C and more cardiovascular complications.
Q: How does vitamin C improve cardiovascular function in people with diabetes?
A: Research published in Frontiers in Nutrition shows that vitamin C improves endothelial function, which helps regulate blood flow and blood pressure.9 It also reduces inflammatory markers.
Q: Which foods are the richest sources of vitamin C?
A: According to data from the Indian Journal of Clinical Biochemistry, guava, oranges, lemons and especially amla (Indian gooseberry) are top sources. Amla contains up to 600 mg of vitamin C per 100 grams, far more than typical fruits like apples.
Q: What are the best steps to take if I have Type 2 diabetes and want to protect my heart?
A: Start by eating fresh vitamin C-rich fruits daily, eliminating vegetable oils, consuming healthy carbohydrates like fruit and white rice, and tracking your insulin resistance with the HOMA-IR test. These steps target the root causes of mitochondrial dysfunction that increase cardiovascular risk.
