First: Two Things That Need Fast Action
If your heart is racing AND you feel shaky, sweaty, confused, or suddenly hungry — check your blood sugar. This can be hypoglycemia (low blood sugar), and it needs treating within minutes. If you can’t test, treat anyway: 15g fast sugar (juice, glucose tabs), recheck in 15 minutes. If you can’t be roused, or a seizure occurs — that’s a 911 emergency. See does diabetes cause low blood sugar?
Call 911 if a racing heart comes with:
- Chest pain or pressure · fainting or near-fainting · severe shortness of breath
- A heartbeat that is fast and irregular, or won’t slow down
Remember: with diabetes, a heart attack can be “silent.” Don’t wait for chest pain. See does diabetes cause chest pain?
What You Need to Know
- Yes — diabetes can cause a rapid heart rate, through several different mechanisms. Some are harmless and temporary; one is a serious warning sign.
- The one that matters most: a persistently raised resting heart rate can be an early sign of cardiac autonomic neuropathy (CAN) — nerve damage affecting the heart.
- CAN is common and underdiagnosed — affecting roughly 35% of people with type 1 and 44% with type 2 diabetes, and it’s a strong independent predictor of cardiovascular death (NIH).
- A fast heartbeat can also be low blood sugar — which needs treating in minutes (see above).
- A resting heart rate persistently above ~100 bpm deserves a doctor’s attention, not a wait-and-see.
The Short Answer
Diabetes can raise your heart rate in several ways — some benign, some not. A brief spike after coffee, stress, or exercise is normal. But a resting heart rate that stays high, or a heart rate that no longer responds normally to activity, can signal something more serious: damage to the nerves that regulate your heart.
Understanding which is which is the point of this page.
The Big One: Cardiac Autonomic Neuropathy (CAN)
This is the most important cause to understand, and the one most people — and many clinicians — miss.
Your heart rate is normally controlled by the autonomic nervous system, which speeds the heart up and slows it down without you thinking about it. Prolonged high blood sugar can damage these nerves, just as it damages nerves in the feet. When it affects the heart, it’s called cardiac autonomic neuropathy.
How it shows up — and the order matters:
The vagus nerve (which normally slows the heart) is damaged first. With its braking action weakened, the heart’s accelerator runs unopposed — producing a resting tachycardia, often in the 90–100+ bpm range (ScienceDirect review). Later, as the condition advances, the heart rate can become “fixed” — stuck at one rate and no longer rising and falling normally with exertion, stress, or sleep.
The classic signs of CAN:
- A high resting heart rate that doesn’t have another explanation
- A heart rate that barely changes when you exercise, or a fixed rate
- Dizziness or light-headedness on standing (orthostatic hypotension)
- Reduced exercise tolerance — tiring far sooner than expected
- Palpitations — though many people have no symptoms at all in the early stages
Why it’s serious, stated plainly: CAN is not just a symptom. It’s an independent predictor of cardiovascular events, silent heart attacks, and sudden cardiac death (Frontiers in Neuroscience). It’s also common — up to 60% in people with longstanding diabetes — and it’s frequently overlooked because the early signs are non-specific.
This is why a persistently elevated resting heart rate in someone with diabetes should never be shrugged off. It’s exactly the kind of thing worth raising with your doctor, who can screen for CAN with simple heart-rate-response tests.
The Other Causes of a Fast Heart Rate in Diabetes
Not every racing heart is CAN. Diabetes drives heart rate up through several other routes:
Low blood sugar (hypoglycemia) — the urgent one
When blood sugar drops, the body releases adrenaline — and a pounding, racing heart is one of the first warnings, alongside shakiness, sweating, and hunger. This needs treating within minutes (see the box at the top). See does diabetes cause low blood sugar?
High blood sugar and dehydration
Very high blood sugar makes you urinate more, which can lead to dehydration — and dehydration itself raises heart rate. In severe cases (diabetic ketoacidosis), a fast heartbeat is one of several emergency signs. See does diabetes cause dehydration?
Anxiety
Living with a chronic condition raises anxiety, and anxiety causes a genuinely fast heartbeat — sometimes indistinguishable from a physical cause. Real, but a diagnosis of exclusion. See can diabetes cause anxiety?
Overlapping heart and blood-pressure problems
Diabetes clusters with high blood pressure and heart disease, both of which affect heart rate and rhythm. See the link between diabetes and high blood pressure and in tune with the beat of your heart.
Palpitations vs. rapid heart rate
A “fluttering” or “skipped beat” (palpitation) isn’t quite the same as a sustained fast rate, though they overlap and both warrant checking. See can diabetes cause heart palpitations?
Everyday causes — don’t forget these
Caffeine, some medications, fever, thyroid problems (more common in diabetes), and simple deconditioning all raise heart rate. See caffeine.
When a Fast Heart Rate Is an Emergency
Call 911 if a rapid heartbeat comes with:
- Chest pain or pressure (and remember — with diabetes this may be absent even during a heart attack)
- Fainting or near-fainting
- Severe shortness of breath
- A pulse that is both fast and irregular, or one that won’t come down
An irregular fast rhythm can be atrial fibrillation, which is more common in people with diabetes and raises stroke risk — it needs proper diagnosis and treatment, not reassurance. See ER, urgent care, or wait?
What You Can Do
Know your resting heart rate. Check it when you’re calm and still — a normal resting rate is roughly 60–100 bpm. If yours is persistently near or above 100, note it and tell your doctor. Wearables and home blood-pressure monitors make this easy to track over time.
Manage the root cause. Steady blood sugar over years is what prevents the nerve damage behind CAN in the first place. Blood pressure and cholesterol control matter just as much — see does diabetes cause high cholesterol?
Move — appropriately. Regular exercise lowers resting heart rate and improves autonomic function. If you have known heart disease or advanced CAN, get guidance first, since exercise tolerance can be affected. See fight disease with diet and exercise.
Cut the obvious triggers — excess caffeine, dehydration, poor sleep.
Review your medications with a pharmacist — some raise heart rate, and some diabetes medications (SGLT2 inhibitors, GLP-1 agonists) actively protect the heart. See making the most of your medications.
Ask about screening. If you’ve had diabetes for years, or have a high resting heart rate, ask your doctor about CAN screening — it’s simple and it’s under-used. See getting the most from your doctor and have you had a check-up lately?
The Bottom Line
Diabetes can cause a rapid heart rate through low blood sugar, dehydration, anxiety, and everyday triggers — but the one that matters most is a persistently raised resting heart rate, which can be an early sign of cardiac autonomic neuropathy, a serious and treatable complication.
A racing heart with shakiness and sweating? Check your sugar now. A resting heart rate that stays high? Don’t wait — get it checked. And with diabetes, never assume a normal heart just because there’s no chest pain.
Related Reading
- Does Diabetes Cause Chest Pain?
- Can Diabetes Cause Heart Palpitations?
- Does Diabetes Cause Low Blood Sugar?
- The Link Between Diabetes and High Blood Pressure
- Can Diabetes Cause Anxiety?
- In Tune With the Beat of Your Heart
- ER, Urgent Care, or Wait? How to Decide
Sources:
- NIH / NCBI — Cardiovascular Autonomic Neuropathy
- NIH / NCBI — Cardiac Autonomic Neuropathy in Diabetes: A Predictor of Cardiometabolic Events
- ScienceDirect — Cardiac Autonomic Neuropathy in Type 1 and 2 Diabetes: Epidemiology, Pathophysiology, and Management
- CDC — Diabetes and Your Heart
- Mayo Clinic — Tachycardia
This article is for information only and is not a substitute for medical care. If you have a fast heartbeat with chest pain, fainting, or severe breathlessness, call 911.
The post Can Diabetes Cause Rapid Heart Rate? The Hidden Cause appeared first on The Health Pages | Online Health Care Information Resources.
