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Diabetes mellitus

Definition

  • Type 1 – Inability of beta pancreatic islet cells to produce insulin. An autoimmune response destroys the beta cells.
  • Type 2 – Inability of pancreatic cells to produce enough insulin to meet the body’s demands, or an insensitivity of tissues to insulin, resulting in inappropriate uptake of glucose.

 

Risk Factors

  • Type 1 –
    • Family history
    • Other autoimmune diseases
  • Type 2 –
    • Family history
    • Overweight/obesity
    • Sedentary lifestyle
    • Waist size
    • Ethnicity (SE Asian/African)
    • Hypertension
    • Gestational diabetes
    • Advanced age

 

Differential diagnoses

  • Other endocrine problems – eg hypothyroidism
  • Anaemia

 

Epidemiology

  • Worldwide prevalence of 415 million, 642 million by 2040: 1 in 10
  • 4 million in the UK
  • Over 1 in 16
  • 90% are type 2
  • Slightly higher prevalence in men – 56%
  • Peak age of type 1 diabetes diagnosis is 9-14

 

Aetiology

  • Type 1 – Autoimmune response to beta islet cells
  • Type 2 – Insufficient production of insulin for body’s requirement, or insufficient uptake of insulin (reduced insulin sensitivity)

 

Clinical features

  • Frequent urination (during the night, bedwedding in children)
  • Thirst
  • Lethargy, tiredness
  • Weight loss
  • Frequent UTI
  • Sensory loss
  • Slow wound healing
  • Type 1 – usually present quite early, so less end-organ damage, often present with weight-loss, lethargy and urinary changes, may present with ketoacidosis
    • Kussmaul’s respirations
    • Sweet-smelling breath
    • Loss of consciousness
  • Type 2 – may present with end-organ damage such as diabetic retinopathy, diabetic nephropathy, peripheral neuropathy, autonomic neuropathy, cardiovascular disease

 

Pathophysiology

  • High blood glucose
    • Osmotic diuresis – frequent urination, thirst
    • Diabetic retinopathy from high glucose in the vessels of the eye – changes refraction of light
    • Genital thrush (high glucose levels in urine)
  • Reduced glucose availability for respiration
    • Tiredness, muscle breakdown (weight loss),
  • Neuropathy from high glucose levels
    • Sensory loss
    •  

 

Investigations

  • Fasting glucose >7mmol/L
  • Random glucose >11.1mmol/L
  • Glucose tolerance: 75g – above cut offs used for fasting and 2-hour measurements
  • HbA1c – Hb bound glucose
  • Assessment of end-organ damage, eg fundoscopy, U&Es, limb exams

 

Management

  • Some cases of type 2 can be managed by diet, medication and lifestyle alone
  • Other type 2, and type 1 require insulin therapy
    • Basal-bolus regimen is a good way to balance insulin levels throughout day
    • Often have to calculate dose ‘units’ based on carbohydrate intake
    • Insulin pump if cannot maintain good control
  • Medication
    • Metformin – first line drug
    • Gliptin -
    • Sulfonylurea -

 

Prognosis

  • Life expectancy is reduced, as a result of complications
    • Type 1 – about 69
    • Type 2 – reduction in life expectancy up to 10 years
  • Cardiovascular disease is common
  • Renal dysfunction is common
  • Amputations, sensory neuropathy and associated foot problems
  • Depression
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