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Prediabetes represents a critical turning point in metabolic health—a condition where blood sugar levels have risen above normal but haven’t yet crossed the threshold into type 2 diabetes. One in 3 adults in China and the United States have prediabetes, making this a widespread public health concern that demands attention. What many people don’t realize is that prediabetes isn’t just a warning sign for diabetes; it’s also a significant risk factor for cardiovascular disease that can begin damaging your heart and blood vessels long before diabetes develops.
Understanding the intricate connection between prediabetes and heart health is essential for anyone looking to protect their cardiovascular system and prevent serious complications. This comprehensive guide explores how prediabetes affects your heart, the mechanisms behind this relationship, and the evidence-based strategies you can implement to safeguard your cardiovascular health.
What Is Prediabetes and How Common Is It?
Prediabetes occurs when blood glucose levels are higher than normal but not high enough to be classified as diabetes. This intermediate stage between normal glucose regulation and diabetes represents a crucial window of opportunity for intervention. When you eat, your body breaks down food into glucose, which enters your bloodstream. A hormone called insulin, produced by the pancreas, helps move glucose from the blood into the cells.
In prediabetes, this system begins to malfunction. Prediabetes can develop when the body does not produce enough insulin or when the body’s cells become resistant to insulin, a condition known as insulin resistance. The prevalence of this condition is staggering and continues to grow. In the USA, data from the Centres for Disease Control and Prevention show that 38% of adults (aged 18 years and older) were living with prediabetes in 2021 (98 million), a proportion rising to 49% in those aged 65 years and older.
The global picture is equally concerning. According to the International Diabetes Federation Atlas, 10th Edition, 541 million adults around the world were living with prediabetes in 2021—a number similar to the number of people living with diabetes. Despite these alarming numbers, many people are unaware they have it because the condition typically causes no symptoms.
Diagnosing Prediabetes: Understanding the Numbers
Early detection of prediabetes is crucial for preventing both diabetes and cardiovascular complications. Healthcare providers use several blood tests to diagnose this condition, each measuring different aspects of blood sugar control.
Hemoglobin A1C Test
This test measures the percentage of hemoglobin in the blood that has glucose attached to it and reflects the average blood sugar level over the previous two to three months. An A1C level between 5.7% and 6.4% indicates prediabetes, while 6.5% or higher suggests diabetes.
Fasting Plasma Glucose Test
This test measures blood sugar after not eating for at least eight hours. A fasting blood glucose level between 100 and 125 mg/dL indicates prediabetes, while levels of 126 mg/dL or higher on two separate occasions indicate diabetes.
Oral Glucose Tolerance Test
This test measures how your body reacts two hours after you have been given a special sugary drink. A blood glucose level between 140 and 199 mg/dL two hours after drinking the glucose solution indicates prediabetes.
You should be tested for prediabetes if you are overweight or have obesity and have one or more other risk factors for diabetes, or if your parents, siblings, or children have type 2 diabetes. Even if you don’t have risk factors, you should start getting tested once you reach age 45.
The Cardiovascular Risks of Prediabetes: What the Research Shows
For years, prediabetes was viewed primarily as a precursor to diabetes, but mounting evidence reveals that it poses independent risks to cardiovascular health. The research paints a concerning picture of how even moderately elevated blood sugar levels can damage the heart and blood vessels.
Increased Risk of Heart Disease and Stroke
In the general population, prediabetes was associated with an increased risk of all cause mortality (relative risk 1.13), composite cardiovascular disease (1.15), coronary heart disease (1.16), and stroke (1.14) in a median follow-up time of 9.8 years. These statistics translate into real-world consequences: thousands of additional heart attacks and strokes each year among people with prediabetes.
The risks are even more pronounced in certain populations. People with elevated blood sugar levels have a 30% to 47% higher risk of developing a cardiovascular disease problem such as stroke or heart failure, even when they have prediabetes. Research has also revealed gender differences in cardiovascular risk. Women with prediabetes or undiagnosed diabetes had a 47% and 33% increased risk, respectively, compared to women with “normal” blood sugar levels.
The Reality of Major Adverse Cardiovascular Events
A landmark study examining prediabetes and cardiovascular outcomes found sobering results. Serious cardiovascular events occurred in 18% of people with prediabetes compared with 11% of people with normal blood sugar levels over a median of five years follow-up. Having prediabetes nearly doubled the chance of a major adverse cardiovascular event, which accounts for 1 out of 4 deaths in the U.S.
What makes these findings particularly significant is that the relationship between higher blood sugar levels and cardiovascular events remained significant even after taking into account other factors that could play a role, such as age, gender, body mass index, blood pressure, cholesterol, sleep apnea, smoking and peripheral artery disease. This suggests that prediabetes itself—not just its associated risk factors—contributes to cardiovascular disease.
Heart Failure Risk
Prediabetes is associated with increased risk of cardiovascular disease and heart failure. Research examining which cardiovascular event occurs first in people with prediabetes has provided valuable insights. In 40,117 participants with 638,910 person-years of follow-up, 5781 cases of incident ASCVD and 3179 cases of incident HF occurred, demonstrating that both atherosclerotic cardiovascular disease and heart failure represent significant threats.
How Prediabetes Damages the Heart and Blood Vessels
Understanding the mechanisms by which prediabetes harms cardiovascular health helps explain why intervention is so critical. The damage occurs through multiple interconnected pathways that begin long before diabetes develops.
Insulin Resistance and Hyperinsulinemia
At the heart of prediabetes lies insulin resistance. Insulin resistance is when cells in your muscles, fat, and liver don’t respond well to insulin and can’t easily take up glucose from your blood. In response, your pancreas makes more insulin to help glucose enter your cells, leading to elevated insulin levels in the bloodstream—a condition called hyperinsulinemia.
Recent research has revealed that hyperinsulinemia itself may drive cardiovascular damage. Prolonged hyperinsulinemia for 48 h led to hypertrophy of cardiomyocytes and vascular smooth muscle cells, as well as elevated intracellular calcium, both of which are known to contribute to vascular dysfunction and hypertension. The hypertrophy of vascular endothelial and smooth muscle cells leads to the thickening of the tunica intima and media, resulting in a decrease in lumen volume and an increase in blood pressure.
Blood Vessel Damage and Atherosclerosis
Prediabetes is thought to play a role in heart health because elevated glucose levels in the blood can damage and cause inflammation within the vessels. This causes injury to the vessels in the body and can lead to narrowing of the vessels and ultimately cardiovascular injury. Elevated blood sugar damages blood vessels and can accelerate atherosclerosis (plaque buildup in the arteries).
Some people with prediabetes may have changes in their blood vessels. Changes in your blood vessels can lead to some of the same health problems caused by type 2 diabetes. This vascular damage begins early in the disease process, often before people even know they have prediabetes.
Endothelial Dysfunction
The endothelium—the inner lining of blood vessels—plays a crucial role in cardiovascular health. Endothelial dysfunction, which reflects nitric oxide deficiency, is a characteristic feature of insulin-resistant states, including diabetes, prediabetes, and obesity, and is a central mechanism linking insulin resistance and ASCVD at the cellular level. When the endothelium doesn’t function properly, blood vessels can’t dilate appropriately, blood clots form more easily, and inflammation increases.
Pathophysiological Defects
The pathophysiologic defects underlying prediabetes include insulin resistance, alpha- and beta-cell dysfunction, increased lipolysis, inflammation, and suboptimal incretin effect. These interconnected abnormalities create a metabolic environment that promotes cardiovascular disease through multiple mechanisms simultaneously.
Risk Factors That Compound Cardiovascular Danger
Prediabetes rarely occurs in isolation. It typically appears alongside other cardiovascular risk factors, creating a dangerous synergy that amplifies heart disease risk.
Metabolic Syndrome
Prediabetes goes hand in hand with metabolic syndrome, the term for a condition that includes hypertension, obesity, and high cholesterol. People with insulin resistance and prediabetes can also develop metabolic syndrome, a group of conditions—including high blood pressure and a large waist size—that increase your risk for heart disease, diabetes, and stroke.
People who have metabolic syndrome—a combination of high blood pressure, abnormal cholesterol levels, and large waist size—are more likely to have prediabetes. This clustering of risk factors creates a particularly hazardous situation for cardiovascular health.
Obesity and Body Fat Distribution
Overweight and obesity are the most common risk factors associated with the development of T2DM. However, not all body fat poses equal risk. Experts believe obesity, especially too much fat in the abdomen and around the organs, called visceral fat, is a main cause of insulin resistance.
A waist measurement of 40 inches or more for men and 35 inches or more for women is linked to insulin resistance. This is true even if your body mass index (BMI) falls within the normal range. Interestingly, research has shown that Asian Americans may have an increased risk for insulin resistance even without a high BMI.
Hypertension
High blood pressure frequently accompanies prediabetes and insulin resistance. Hyperinsulinemia plays a crucial role in the development of hypertension. The relationship is bidirectional—insulin resistance contributes to high blood pressure, while hypertension further damages blood vessels and worsens cardiovascular risk.
Dyslipidemia
Other risk factors include central obesity, hypertriglyceridemia, and low HDL-cholesterol. The traditional CVD risk factors (dyslipidemia, obesity, hypertension) are quite prevalent among individuals with prediabetes. This abnormal lipid profile—characterized by high triglycerides, low HDL (“good”) cholesterol, and often elevated LDL (“bad”) cholesterol—accelerates atherosclerosis.
Additional Risk Factors
Major risk factors for prediabetes include overweight and obesity, older age (45 years and older), genetic predisposition, unhealthy diet, physical inactivity, socioeconomic deprivation, and having current or previous conditions (eg, metabolic dysfunction-associated steatotic liver disease or gestational diabetes). Race and ethnicity are also contributing factors, with Asian, Black, and Hispanic adults at higher risk of prediabetes than White adults.
Early Cardiovascular Damage: What Happens Before Symptoms Appear
One of the most concerning aspects of prediabetes is that cardiovascular damage begins long before any symptoms appear. In people with prediabetes, some of the long-term damage to the blood vessels, heart, and kidneys may already be starting.
Recent studies have revealed that the long-term complications of diabetes manifest in some people with prediabetes; these complications include microvascular and macrovascular disorders. The macrovascular disorders associated with prediabetes include CVD, stroke, and peripheral vascular disease.
The condition has also been linked to what are called “silent” heart attacks, with symptoms so mild people may not realize they occurred. These silent events can still cause significant damage to the heart muscle and increase the risk of future cardiovascular problems.
Observational follow-up studies, often more than 20 years in duration, have confirmed the increased risk of mortality from cardiovascular disease and other causes in patients with prediabetes compared to patients with normal glucose tolerance. This long-term perspective underscores the importance of early intervention.
The Power of Prediabetes Remission for Heart Health
While the cardiovascular risks of prediabetes are significant, there’s encouraging news: achieving remission from prediabetes can dramatically reduce these risks. Reaching prediabetes remission by restoring normal glucose regulation has been shown to profoundly reduce future type 2 diabetes risk outlasting the time of lifestyle intervention.
Recent landmark research has revealed even more impressive cardiovascular benefits. Reaching prediabetes remission is linked to a decades-long benefit, halving the risk of cardiovascular death or hospitalisation for heart failure in diverse populations. This finding represents a paradigm shift in how we think about prediabetes management.
Prediabetes is the last point on the glycaemic spectrum at which type 2 diabetes can still be halted. Yet, prediabetes has long been viewed as just a risk factor rather than a key opportunity for prevention. The evidence now clearly shows that treating prediabetes isn’t just about preventing diabetes—it’s about protecting the heart.
Lifestyle Interventions: Your First Line of Defense
Multicomponent lifestyle interventions, including diet and physical activity targeting weight loss are recommended for prediabetes management. The good news is that these interventions have been proven effective in large-scale clinical trials.
Weight Loss: A Powerful Intervention
Taking small steps, such as eating healthier foods and moving more to lose weight, can help reverse insulin resistance and prevent or delay type 2 diabetes in people with prediabetes. The National Institutes of Health-funded research study, the Diabetes Prevention Program (DPP), showed that for people at high risk of developing diabetes, losing 5 to 7 percent of their starting weight helped reduce their chance of developing the disease.
Even losing 5-7 percent of body weight can cut diabetes risk significantly (sometimes in half), as obesity is a major risk factor. For someone weighing 200 pounds, this means losing just 10 to 14 pounds can make a significant difference in both diabetes and cardiovascular risk.
Lifestyle changes can reduce the risk of developing type 2 diabetes by about 50% and may even reverse prediabetes. The cardiovascular benefits extend beyond diabetes prevention. The 30-year data from the Da Qing Study showing a 26% reduction in cardiovascular events, 33% reduction in cardiovascular mortality, and 26% reduction in all-cause mortality in participants previously receiving a lifestyle intervention.
Physical Activity Recommendations
Get at least 150 minutes of moderate exercise per week, such as walking, aerobics, cycling, dancing or swimming. This breaks down to just 30 minutes of activity on five days per week—a manageable goal for most people.
Strength training can also help improve insulin sensitivity. Combining aerobic exercise with resistance training provides comprehensive benefits for metabolic health and cardiovascular function. Physical activity and losing weight if you need to may help your body respond better to insulin.
Dietary Strategies for Heart Health
Focus on a balanced, whole-food diet rich in vegetables, lean proteins, healthy fats and moderate amounts of high-fiber, unprocessed carbs. When choosing carbohydrate foods, opt for those that retain their original food matrix, including fiber, micronutrients and phytochemicals, which all contribute to your health and slow your body’s glycemic response.
Key dietary principles include:
- Emphasize whole grains over refined carbohydrates
- Include plenty of vegetables and fruits, which provide fiber and antioxidants
- Choose lean protein sources such as fish, poultry, legumes, and plant-based proteins
- Incorporate healthy fats from sources like olive oil, nuts, seeds, and avocados
- Limit added sugars and highly processed foods
- Control portion sizes to support weight management
- Stay hydrated with water rather than sugary beverages
Sleep and Stress Management
Both conditions directly affect metabolic function, hormone balance and blood sugar levels. Poor sleep quality and chronic stress can worsen insulin resistance and increase cardiovascular risk. Aim for 7-9 hours of quality sleep per night and implement stress-reduction techniques such as meditation, yoga, deep breathing exercises, or other relaxation practices.
Medical Management and Monitoring
While lifestyle changes form the foundation of prediabetes management, medical interventions may also play an important role in protecting cardiovascular health.
Medications for Prediabetes
Prediabetes can be treated or reversed by intensive lifestyle modification involving calorie restriction and increased physical activity, or, less effectively, by metformin in some groups. Metformin, a medication commonly used for type 2 diabetes, has been shown to reduce the risk of progression from prediabetes to diabetes in certain populations, particularly those who are younger, have higher BMI, or have a history of gestational diabetes.
Managing Cardiovascular Risk Factors
The increased risks seen in both men and women could be mitigated through modifiable factors, including weight reduction strategies and greater use of antihypertensive and statin medications. Screening and appropriate management of prediabetes might contribute to primary and secondary prevention of cardiovascular disease.
Comprehensive cardiovascular risk management in people with prediabetes should address:
- Blood pressure control through lifestyle changes and medication if needed
- Cholesterol management with statins or other lipid-lowering medications when appropriate
- Antiplatelet therapy in select high-risk individuals
- Smoking cessation for those who use tobacco
- Regular monitoring of blood glucose, blood pressure, and lipid levels
The Role of Newer Medications
In the 2024 STEP 10 trial in people with obesity and prediabetes, 81% of participants treated with semaglutide 2·4 mg reverted to normoglycaemia compared with only 14% in the placebo group. While these newer medications show promise, they are typically reserved for specific situations and should be used in conjunction with lifestyle modifications.
Special Considerations for High-Risk Populations
Certain groups face elevated cardiovascular risks from prediabetes and may require more intensive monitoring and intervention.
People with Existing Cardiovascular Disease
In patients with atherosclerotic cardiovascular disease, prediabetes was associated with an increased risk of all cause mortality (relative risk 1.36), composite cardiovascular disease (1.37), and coronary heart disease (1.15) in a median follow-up time of 3.2 years. Over a median follow-up of 3·2 years, prediabetes was linked to a 36% increase in all-cause mortality and 37% increase in cardiovascular disease.
These individuals require particularly aggressive management of all cardiovascular risk factors and close collaboration between their endocrinologist and cardiologist.
Women with Prediabetes
Women with prediabetes had higher cardiovascular risks than men, but this was reduced when lifestyle factors and medications were considered. In studies that further stratify results by sex, the relative risk of CHD is higher in women than men in the presence of diabetes. This suggests that women with prediabetes may benefit from particularly proactive cardiovascular risk management.
Racial and Ethnic Disparities
The relationship between prediabetes and events were strongest among males, Blacks and people with a family history of cardiovascular disease or personal risk factors for heart disease. Understanding these disparities is crucial for ensuring equitable access to screening, prevention, and treatment services.
Monitoring Your Progress and Long-Term Management
Successfully managing prediabetes and protecting your heart requires ongoing commitment and regular monitoring.
Regular Testing Schedule
If the results are normal but you have other risk factors for diabetes, you should be retested at least every 3 years. Those with prediabetes typically need more frequent monitoring—often every 6-12 months—to track progress and detect any progression toward diabetes.
Comprehensive Cardiovascular Assessment
Beyond blood glucose monitoring, people with prediabetes should have regular assessments of:
- Blood pressure at every healthcare visit
- Lipid panel (cholesterol and triglycerides) annually or as recommended
- Body weight and waist circumference to track progress
- Kidney function through blood and urine tests
- Cardiovascular symptoms such as chest pain, shortness of breath, or unusual fatigue
Working with Your Healthcare Team
The National Diabetes Prevention Program works to make it easier for people with prediabetes to participate in affordable, high-quality lifestyle change programs to reduce their risk of type 2 diabetes and improve their overall health. Its CDC-recognized lifestyle change program is an evidence-based approach that focuses on healthy eating and physical activity. People with prediabetes who take part in a structured lifestyle change protocol can cut their risk of developing type 2 diabetes by 58% (71% for people over 60 years old).
Your healthcare team may include:
- Primary care physician for overall coordination of care
- Endocrinologist for specialized diabetes and metabolic management
- Cardiologist if you have existing heart disease or high cardiovascular risk
- Registered dietitian for personalized nutrition counseling
- Diabetes educator for comprehensive lifestyle coaching
- Exercise physiologist for safe and effective physical activity planning
Understanding the Urgency: Why Action Matters Now
Prediabetes itself can significantly boost someone’s chance of having a major cardiovascular event, even if they never progress to having diabetes. This finding challenges the traditional view that prediabetes is merely a warning sign and underscores the need for immediate action.
Even if blood sugar levels went back to normal range, it didn’t really change their higher risk of having an event, so preventing prediabetes from the start may be the best approach. While this finding is concerning, it emphasizes the importance of early intervention before prediabetes develops.
The rising number of people with prediabetes worldwide, which directly fuels the type 2 diabetes epidemic, is a looming public health crisis that must be addressed. Early detection and treatment of prediabetes is essential to prevent crippling already overstretched and underfunded health-care systems from surging type 2 diabetes cases and mitigate the economic burden on societies of treating this costly condition and its complications.
Practical Steps to Get Started Today
If you have prediabetes or are at risk, taking action now can protect your heart and prevent progression to diabetes. Here are concrete steps you can implement immediately:
This Week
- Schedule a comprehensive health screening if you haven’t had one recently
- Start tracking your food intake to identify areas for improvement
- Add 10 minutes of walking to your daily routine
- Replace one sugary beverage with water each day
- Measure your waist circumference to establish a baseline
This Month
- Meet with a registered dietitian for personalized nutrition guidance
- Increase physical activity to 30 minutes most days of the week
- Identify and address sleep issues that may be affecting your metabolic health
- Learn stress management techniques and practice them daily
- Join a diabetes prevention program if available in your area
This Year
- Achieve a 5-7% weight loss if you’re overweight or obese
- Establish consistent exercise habits including both aerobic and strength training
- Optimize all cardiovascular risk factors including blood pressure and cholesterol
- Build sustainable healthy eating patterns that you can maintain long-term
- Develop a strong support network of healthcare providers, family, and friends
The Bottom Line: Prediabetes Is a Call to Action
Prediabetes is a condition of high risk for cardiovascular disease (CVD) and other comorbidities. The evidence is clear and compelling: prediabetes significantly increases your risk of heart attack, stroke, heart failure, and cardiovascular death. However, this elevated risk is not inevitable.
Fortunately, both insulin resistance and prediabetes can often be improved, or even reversed in some cases, with the right steps and treatments. The key is recognizing prediabetes not as a benign condition or merely a diabetes risk factor, but as a serious cardiovascular threat that demands immediate attention and action.
By implementing evidence-based lifestyle changes, working closely with your healthcare team, managing all cardiovascular risk factors, and maintaining long-term commitment to your health, you can dramatically reduce your risk of both diabetes and heart disease. Targeting remission might represent a new approach to cardiovascular prevention.
The journey from prediabetes to optimal health requires dedication, but the rewards—a healthier heart, reduced disease risk, improved quality of life, and potentially decades of additional healthy years—make every effort worthwhile. Don’t wait for symptoms to appear or for prediabetes to progress to diabetes. Take control of your metabolic and cardiovascular health today.
For more information about diabetes prevention and heart health, visit the CDC’s National Diabetes Prevention Program, the American Heart Association, or the American Diabetes Association. These organizations offer valuable resources, support programs, and tools to help you protect your heart and prevent diabetes.