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What is diabetes? Diabetes mellitus explained
Key takeaways
- Diabetes mellitus is a chronic disease where blood glucose stays too high because the body makes too little insulin or can't use it well.
- Yes, diabetes is a disease — a long-term condition that can be managed but usually not cured.
- Main types: type 1 (autoimmune), type 2 (about 90–95% of cases), and gestational.
- About 40 million people in the US — 12% of the population — have diabetes (CDC, 2023).
Diabetes definition
Diabetes mellitus is a long-term (chronic) disease in which the level of glucose in your blood is too high. The name comes from Greek and Latin: diabetes ("passing through," for the frequent urination) and mellitus ("honey-sweet," because sugar spills into the urine). When people say "diabetes," they almost always mean diabetes mellitus — not the rare, unrelated diabetes insipidus.
How insulin and glucose work
- Food — especially carbohydrates — is broken down into glucose, which enters your blood.
- The pancreas releases insulin, a hormone that acts like a key, letting glucose move into cells for energy.
- In diabetes, there's too little insulin (type 1), or cells don't respond to it properly — insulin resistance (type 2) — so glucose builds up in the blood.
Main types at a glance
| Type | What happens | Share of cases |
|---|---|---|
| Type 1 | The immune system destroys insulin-making cells; insulin is required | About 5–10% |
| Type 2 | Insulin resistance plus gradually falling insulin production | About 90–95% |
| Gestational | High glucose first found in pregnancy | About 5–9% of US pregnancies |
| Other | LADA, MODY, and diabetes caused by other diseases or medicines | Less common |
More detail: types of diabetes.
How common is diabetes?
The CDC reports that about 40.1 million people in the US had diabetes in 2023 (12.0%), including about 11 million adults who were undiagnosed, and 115 million adults had prediabetes. Worldwide, the WHO counts hundreds of millions of adults living with diabetes.
Why it matters
Over time, high blood sugar damages blood vessels and nerves. Diabetes raises the risk of heart attack, stroke, kidney disease, vision loss, nerve damage, and foot ulcers. The good news: keeping glucose, blood pressure, and cholesterol in range dramatically lowers those risks.
How it's diagnosed
A blood test — A1C, fasting glucose, or an oral glucose tolerance test. An A1C of 6.5% or higher, or a fasting glucose of 126 mg/dL or higher, is in the diabetes range. See diabetes tests.
Living with diabetes? Cardivo keeps your glucose readings next to heart rate, blood pressure, and mood, with a PDF report for your doctor.
This guide is general wellness education based on the public sources below. It is not medical advice, diagnosis, or treatment. Cardivo is not a medical device. If you think you are having a medical emergency, call 911.
Frequently asked questions
What is diabetes in simple words?
Diabetes is a long-term condition where your blood sugar stays too high because your body doesn't make enough insulin or can't use it well.
Is diabetes a disease?
Yes. Diabetes mellitus is a chronic disease. It can be managed with lifestyle, medication, and monitoring, but type 1 and most type 2 diabetes are not cured.
What does diabetes mellitus mean?
The term comes from Greek and Latin words meaning roughly 'passing through' and 'honey-sweet' — describing frequent urination of sugary urine.
Sources
- NIDDK — What is diabetes?
- CDC — National diabetes statistics
- World Health Organization — Diabetes fact sheet