Diabetes: Symptoms, Causes, Types and Treatment

Diabetes is a chronic condition in which the body either doesn't produce enough insulin or can't use it effectively, causing blood sugar (glucose) levels to rise higher than normal. Left unmanaged, high blood sugar can gradually damage blood vessels, nerves, and organs — but with the right diagnosis and treatment, diabetes is very manageable, and many complications are preventable. This guide covers the main types, common symptoms, how it's diagnosed and treated, and when to see a doctor.

Types of Diabetes

Diabetes isn't a single disease — the main types differ in cause and management:

• Type 1 diabetes — an autoimmune condition in which the immune system attacks the insulin-producing cells in the pancreas, usually diagnosed in children or young adults. It always requires insulin treatment.
• Type 2 diabetes — the most common form, where the body becomes resistant to insulin or doesn't produce enough of it. It develops gradually and is strongly linked to genetics and lifestyle factors. Our Type 2 diabetes guide covers this specifically.
• Gestational diabetes — diabetes that develops for the first time during pregnancy, usually resolving after delivery, though it raises the future risk of Type 2 diabetes for both mother and child.
• Prediabetes — blood sugar that's higher than normal but not yet high enough to be classified as diabetes; an important stage where lifestyle changes can often prevent or delay progression.

Recognizing the Symptoms

Common symptoms across types of diabetes include increased thirst, frequent urination, unexplained fatigue, blurred vision, and slow-healing cuts or wounds. Type 1 diabetes symptoms often appear suddenly, over days or weeks. Type 2 diabetes tends to develop so gradually that symptoms can go unnoticed for years, which is part of why routine screening matters.

What Causes Diabetes

The underlying cause differs by type. Type 1 diabetes results from an autoimmune process that isn't fully understood and isn't preventable. Type 2 diabetes develops from a combination of insulin resistance, genetics, excess body weight, and inactivity — usually several factors together rather than one single cause. Gestational diabetes is driven by pregnancy-related hormonal changes that affect how the body responds to insulin.

How Diabetes Is Diagnosed

Diagnosis relies on blood tests rather than symptoms alone, since Type 2 diabetes and prediabetes are often symptom-free in their early stages. Common tests include fasting blood glucose, HbA1c (a measure of average blood sugar over roughly the past three months), and the oral glucose tolerance test. A single abnormal result is usually confirmed with a repeat test before a diagnosis is made.

Diabetes Treatment

Type 1 diabetes always requires insulin, since the body can no longer produce its own. Type 2 diabetes treatment typically starts with lifestyle changes — diet, physical activity, and weight management — and may add oral medications or insulin if blood sugar targets aren't reached through lifestyle changes alone. Our Type 2 diabetes guide covers day-to-day management in more depth. Gestational diabetes is usually managed with diet and monitoring, with insulin added if needed.

Diabetes Complications

Consistently high blood sugar over years can gradually damage blood vessels and nerves, raising the risk of heart disease, kidney disease, vision loss, and nerve damage — but regular monitoring and blood sugar control substantially reduce these risks. Some GLP-1 weight-loss medications, originally developed for Type 2 diabetes, are also relevant here; our GLP-1 weight-loss injections guide covers that connection.

When to See a Doctor

Seek Urgent Medical Care

• Very high blood sugar together with confusion, rapid breathing, or fruity-smelling breath
• Signs of very low blood sugar that don't improve after eating or drinking something sugary — shakiness, confusion, or fainting
• Sudden vision loss, or severe abdominal pain with vomiting

Book a Doctor's Appointment

• Ongoing thirst, frequent urination, or unexplained fatigue
• A family history of diabetes with no recent screening
• Slow-healing wounds or frequent infections
• Numbness or tingling in the hands or feet