Diabetes Mellitus

Diabetes mellitus is a chronic condition that affects the way the body processes blood sugar (glucose). It occurs when the body either doesn’t produce enough insulin or can’t use the insulin it produces effectively. Insulin is a hormone made by the pancreas that helps glucose enter cells to be used for energy. Without proper management, diabetes can lead to serious health complications.

Causes

There are different types of diabetes, each with different causes:

• Type 1 diabetes: Caused by an autoimmune reaction where the body attacks its own insulin-producing cells in the pancreas
• Type 2 diabetes: Usually due to insulin resistance and relative insulin deficiency, often linked to lifestyle factors
• Gestational diabetes: Develops during pregnancy due to hormonal changes and insulin resistance
• Secondary diabetes: Caused by other conditions such as pancreatic disease, hormonal disorders, or certain medications like steroids

Pathophysiology

In Type 1 diabetes, the immune system destroys beta cells in the pancreas, stopping insulin production. In Type 2 diabetes, cells become resistant to insulin, and the pancreas cannot produce enough insulin to maintain normal glucose levels. This leads to high blood sugar levels, which over time damage organs and blood vessels.

Signs and Symptoms

• Increased thirst and frequent urination
• Unexplained weight loss (more common in Type 1)
• Fatigue and weakness
• Blurred vision
• Slow-healing wounds or infections
• Tingling or numbness in hands and feet (in long-standing cases)
• In Type 2 diabetes, symptoms may be mild and go unnoticed for years

Risk Factors

• Family history of diabetes
• Being overweight or obese
• Sedentary lifestyle
• Age over 45 (though Type 2 is increasingly seen in younger adults)
• Ethnic background (higher risk in South Asian, African, and Caribbean communities)
• History of gestational diabetes or polycystic ovary syndrome (PCOS)

Investigations

1. Blood tests:

• Fasting plasma glucose (≥7.0 mmol/L indicates diabetes)
• HbA1c (≥48 mmol/mol or 6.5%) for long-term glucose control
• Oral glucose tolerance test (OGTT)
• Random plasma glucose (≥11.1 mmol/L with symptoms)

2. Urine tests:

To check for glucose, ketones (in Type 1), or protein (sign of kidney involvement)

3. Imaging:

Rarely needed for diagnosis but may be used to assess complications (e.g. Doppler
studies for vascular disease, eye imaging for retinopathy)

Management

1. Non-Pharmacological Management

• Diet: Emphasis on low glycaemic index foods, fibre, and reduced sugar and saturated fat intake
• Exercise: At least 150 minutes of moderate aerobic activity per week
• Weight loss: Especially important in Type 2 diabetes
• Smoking cessation and alcohol moderation
• Diabetes education: Structured programmes like DESMOND (Type 2) or DAFNE (Type 1)

2. Pharmacological Management

• Type 1 diabetes: Requires lifelong insulin therapy (basal-bolus or insulin pump)
• Type 2 diabetes:
  1. First-line: Metformin (if tolerated)
  2. Second-line: Sulfonylureas, DPP-4 inhibitors, SGLT2 inhibitors or GLP-1 agonists depending on comorbidities
  3. Insulin therapy may be added if oral agents are insufficient
  4. Monitoring: Regular blood glucose and HbA1c checks; blood pressure, lipid levels, and kidney function must also be monitored

3. Surgical Management

Bariatric (weight-loss) surgery may be considered in obese patients with Type 2 diabetes not controlled by medical therapy

Complications

• Microvascular complications:
  1. Diabetic retinopathy (can cause blindness)
  2. Diabetic nephropathy (kidney failure)
  3. Diabetic neuropathy (numbness, pain, or ulcers)
• Macrovascular complications:
  1. Increased risk of heart disease, stroke, and peripheral vascular disease
• Acute complications:
  1. Diabetic ketoacidosis (DKA) in Type 1
  2. Hyperosmolar hyperglycaemic state (HHS) in Type 2
• Other complications:
  1. Foot ulcers and infections
  2. Increased risk of infections generally
  3. Erectile dysfunction and other autonomic neuropathies

References

• NICE Guideline NG17: Type 1 diabetes in adults: diagnosis and management
• NICE Guideline NG28: Type 2 diabetes in adults: management
• Royal College of Physicians: Diabetes and endocrinology audit
• NHS Diabetes Prevention Programme
• GMC Clinical Guidelines and Professional Standards