Overview
Diabetes is a condition where the body cannot regulate blood glucose (sugar) properly. In type 1 diabetes, the immune system destroys insulin-producing cells. In type 2 diabetes, the body does not make enough insulin or does not use it effectively. High blood glucose over time damages blood vessels and nerves throughout the body.
How common is it?
Over 4.5 million people in the UK have diabetes. Type 2 accounts for around 90% of cases. A further 850,000 have type 2 diabetes but do not yet know it.
Causes and risk factors
Type 1 is an autoimmune condition unrelated to lifestyle. Type 2 develops when insulin resistance, usually driven by excess body fat, overwhelms the pancreas's ability to produce enough insulin. Genetics and environment interact.
Common risk factors
- Overweight or obesity (type 2)
- Physical inactivity (type 2)
- Family history of type 2 diabetes
- Age over 40 (type 2)
- South Asian, Black, or African-Caribbean ethnicity (lower BMI threshold)
- Previous gestational diabetes
- Autoimmune factors (type 1)
Symptoms
- Frequent urination, especially at night
- Increased thirst
- Unexplained weight loss
- Blurred vision
- Fatigue
- Slow-healing wounds and infections
- Type 1 can present with sudden severe illness (diabetic ketoacidosis)
- Type 2 is often symptom-free for years
When to see a doctor
See a doctor if you have unexplained thirst, frequent urination, and fatigue. Type 1 diabetes can cause life-threatening diabetic ketoacidosis rapidly. Call 999 if vomiting, breathlessness, and confusion develop in a person with diabetes.
Diagnosis
Fasting plasma glucose or HbA1c blood test confirm diagnosis. In type 1, additional tests for autoantibodies (anti-GAD, anti-IA2) and C-peptide distinguish it from type 2.
Treatments
Lifestyle intervention (type 2)
Weight loss of 10 to 15% of body weight through diet and exercise can achieve remission of type 2 diabetes. NHS Diabetes Prevention Programme and Very Low Calorie Diet programmes are evidence-based options.
Medications (type 2)
Metformin is first-line. SGLT2 inhibitors and GLP-1 agonists have added benefits for heart and kidney protection. Insulin is needed when other drugs are insufficient.
Insulin (type 1 and advanced type 2)
Insulin replacement is essential for type 1 and used in type 2 when oral medications are insufficient. Continuous glucose monitors and insulin pumps are increasingly used.
Self-care and lifestyle
- Eat a balanced diet with reduced refined carbohydrate and sugar content
- Achieve or maintain a healthy body weight
- Exercise at least 150 minutes per week (walking counts)
- Attend annual diabetes review for eye, kidney, and foot checks
Prevention
Type 2 diabetes can be delayed or prevented by achieving and maintaining a healthy weight, eating a balanced diet, and exercising regularly. Type 1 cannot currently be prevented.