Diabetes is a chronic condition where your body can’t properly manage blood sugar levels. Either your pancreas doesn’t produce enough insulin (the hormone that moves sugar from your blood into your cells for energy), or your cells stop responding to insulin the way they should. About 830 million people worldwide have diabetes, and more than half aren’t receiving treatment.
How Insulin and Blood Sugar Normally Work
When you eat, your body breaks down carbohydrates into glucose, a simple sugar that enters your bloodstream. Your pancreas detects that rising blood sugar and releases insulin, which acts like a key, unlocking your cells so glucose can enter and be used for energy. In a healthy system, blood sugar rises after a meal, insulin brings it back down, and your body hums along.
In diabetes, this system breaks down. Without enough working insulin, glucose stays trapped in your bloodstream instead of entering your cells. Your blood sugar climbs higher and stays elevated, a state called hyperglycemia. Over time, that excess sugar damages blood vessels and organs throughout the body.
Type 1 Diabetes
Type 1 diabetes is an autoimmune condition. Your immune system, which normally fights infections, mistakenly attacks the insulin-producing cells in your pancreas. Specific immune cells make direct contact with these cells and destroy them, while inflammatory signals create a feedback loop that accelerates the damage. Eventually, the pancreas produces little to no insulin at all.
Type 1 most often appears in childhood or adolescence, though it can develop at any age. Nearly all children who develop it before age 5 produce antibodies against insulin before symptoms even begin, which is why researchers believe insulin itself may be one of the earliest targets the immune system locks onto. People with type 1 diabetes need insulin replacement (through injections or a pump) every day for the rest of their lives.
Type 2 Diabetes
Type 2 is far more common, accounting for roughly 90 to 95 percent of all diabetes cases. It develops when your cells gradually stop responding to insulin, a process called insulin resistance. Here’s the chain of events: consistently high blood sugar forces your pancreas to pump out more and more insulin to compensate. Over time, your cells become less sensitive to all that insulin. Your pancreas works harder to keep up, but eventually it can’t produce enough to overcome the resistance. Blood sugar stays elevated.
While your body tries to deal with excess sugar, it stores what it can in your liver and muscles. Once those are full, the liver redirects the remaining sugar to be stored as body fat. This is one reason why weight gain and type 2 diabetes are closely linked, though they don’t always go together. You can develop insulin resistance without being overweight.
Key risk factors include a family history of type 2 diabetes, physical inactivity, high triglycerides, high LDL cholesterol, and low HDL cholesterol. Unlike type 1, type 2 often develops gradually over years, frequently passing through a stage called prediabetes before a full diagnosis.
Gestational Diabetes
Some women develop diabetes during pregnancy, typically around the 24th week. Hormonal changes during pregnancy can make cells more resistant to insulin, and for some women, the pancreas can’t produce enough extra insulin to compensate. Gestational diabetes often has no noticeable symptoms, which is why routine screening between weeks 24 and 28 of pregnancy is standard. It usually resolves after delivery, but it significantly raises the mother’s risk of developing type 2 diabetes later in life.
Common Symptoms
The three hallmark symptoms of diabetes are excessive thirst, frequent urination, and extreme hunger. They’re all connected. When blood sugar is too high, your kidneys work overtime to filter out the extra glucose, pulling more water with it. That leads to frequent urination, which dehydrates you and triggers intense thirst. Meanwhile, because glucose isn’t reaching your cells properly, your body signals that it needs more fuel, making you feel unusually hungry even after eating.
Other common signs include unexplained weight loss (especially in type 1), blurry vision, slow-healing cuts or sores, tingling or numbness in your hands and feet, and fatigue. Type 1 symptoms tend to appear suddenly over days or weeks. Type 2 symptoms develop so gradually that many people live with it for years without realizing something is wrong.
How Diabetes Is Diagnosed
The most common diagnostic tool is the A1C test, a blood test that reflects your average blood sugar over the past two to three months. The results break down simply:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
An A1C of 6% corresponds to an average blood sugar of about 126 mg/dL, while 7% corresponds to roughly 154 mg/dL. For people already living with diabetes, the A1C test is also used to track how well blood sugar is being managed over time. Fasting blood glucose tests and oral glucose tolerance tests are alternative methods that can confirm a diagnosis.
Long-Term Complications
Persistently high blood sugar damages small and large blood vessels throughout the body. The organs most affected are the eyes, kidneys, nerves, and heart.
In the eyes, damaged blood vessels in the retina can lead to vision problems and, if untreated, blindness. In the kidneys, damage to the tiny filtering units can cause protein to leak into the urine. This kidney damage, called diabetic nephropathy, affects 15 to 40 percent of people with type 1 diabetes and 5 to 20 percent of those with type 2. Nerve damage affects nearly half of all people with diabetes, causing tingling, numbness, or pain, most often in the feet and hands. It can also affect nerves that control digestion, heart rate, and other automatic body functions.
On the larger scale, diabetes significantly raises the risk of heart attack, stroke, and poor circulation in the legs and feet. These complications aren’t inevitable. Keeping blood sugar, blood pressure, and cholesterol in a healthy range dramatically reduces the risk.
How Diabetes Is Managed
Management depends on the type. People with type 1 diabetes require daily insulin since their bodies produce none. Insulin is delivered through injections multiple times a day or continuously through a small wearable pump. Many people with type 1 also use continuous glucose monitors, small sensors placed just under the skin that track blood sugar levels in real time and send readings to a phone or receiver.
Type 2 diabetes management typically starts with lifestyle changes: regular physical activity, dietary adjustments to reduce blood sugar spikes, and weight management if needed. When lifestyle changes aren’t enough, oral medications that help the body use insulin more effectively or encourage the kidneys to remove excess sugar are common first steps. Some people with type 2 eventually need insulin as well, particularly if the pancreas loses its ability to keep up with demand over the years.
For all types, the day-to-day reality involves monitoring blood sugar, making food choices with carbohydrate content in mind, staying physically active, and keeping regular medical appointments to check for early signs of complications. The goal is to keep blood sugar as close to normal as possible without causing dangerous drops, since blood sugar that falls too low (hypoglycemia) can be just as dangerous in the short term as blood sugar that runs too high.