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Define diabetes mellitus

A group of metabolic diseases of multiple aetiologies characterised by hyperglycemia together with disturbances in fat, protein and carbohydrate metabolism resulting from defects in insulin secretion, insulin action or both


How do you diagnose diabetes mellitus?

• Diagnosing diabetes (worldwide standard)
○ Diagnostic glucose levels (venous plasma) fasting ≥7.0mmol/L, random ≥11.1mmol/L
○ OGTT (oral glucose tolerance test) 2h after 75g CHO≥11.1mmol/L
○ Diagnostic HbA1c ≥48 mmol/mol
• Diagnostic criteria for intermediate diabetes mellitus (worldwide standard)
○ Impaired fasting glucose 6.1-7 mmol/L
○ Impaired glucose tolerance 2h glucose ≥7.8 and <11 mmol/L
○ HbA1c 42-47 mmol
• To diagnose diabetes you need one diagnostic lab glucose plus symptoms
• To ensure that they don't have diabetes you need two diagnostic lab glucoses or HbA1c levels without symptoms


When can HbA1c not be used for diagnosis?

○ The patient is a child or young person
○ Pregnancy (current or recent less than 2 months)
○ Short duration of diabetes symptoms
○ Patients at high risk of diabetes who are acutely ill
○ Patients taking medication that may cause rapid glucose rise
○ Acute pancreatic damage or pancreatic surgery
○ Renal failure
○ Human immunodeficiency virus (HIV) infection
○ Anything where there is drastic changes


Explain MODY

• MODY: Maturity onset diabetes in the young
○ Autosomal dominant
○ Impaired beta cell function
○ Single gene defect
○ Important to take a family history in a patient with new onset diabetes
○ Glucokinase mutations
- Onset at birth
- Stable hyperglycaemia
- Diet treatment
- Complications rare
○ Transcription factor mutations (HNF-1α, HNF-1β, HNF-4α)
- Adolescence/ young adult onset
- Progressive hyperglycaemia
- Management
□ 1/3 diet
□ 1/3 OHA (oral hypoglycemic agent)
□ 1/3 insulin
- Complications frequent


Explain secondary diabetes mellitus

○ Drug therapy e.g. corticosteroids
○ Pancreatic destruction
- Hemochromatosis (excess iron deposition)
- Cystic fibrosis
- Chronic pancreatitis
- Pancreatectomy
○ Recognised genetic syndromes: DIDMOAD
○ Rare endocrine disorders e.g. Cushing's syndrome, Acromegaly pheochromocytoma


Explain gestational diabetes

○ Increasing insulin resistance in pregnancy
○ Associated with family history of type 2 diabetes
○ Increased risk of type 2 diabetes later in life
○ Develops 2nd/3rd trimester
○ More common in overweight and inactive
○ Neonatal problems
- Macrosomia (big baby)
- Respiratory distress
- Neonatal hypoglycaemia


Compare the aetiology of type 1 and type 2 diabetes

Type 1
• Largely unknown
Type 2
• Obesity
• Genetics


Compare the pathology of type 1 and type 2 diabetes

Type 1
• Autoimmune disease
• Beta cells are destroyed and so are unable to produce insulin
Type 2
• Receptors are desensitised to insulin


Who would most likely to have type 1 diabetes?

Younge people


Who would be more likely to have type 2 diabetes?

Older people


Compare the insulin levels of type 1 and type 2 diabetes

Type 1
- Little to none
Type 2
- May initially have hyperinsulinemia but there is a progressive decrease in insulin production (although there will never be no insulin)


What are the symptoms of type 1 diabetes?

• Polydipsia
• Polyuria
• Blurred vision
• Weight loss
• Infections
• Abdominal pain (due to ketones)
• Microvascular: retinopathy, neuropathy, nephropathy
• Macrovascular: MI, stroke, PVD


What are the symptoms of type 2 diabetes?

• May have no symptoms
• Thirst
• Tiredness
• Polyuria
• Sometimes weight loss
• Blurred vision
• Symptoms of complications e.g. CVD


What are the signs of type 1 diabetes?

• Ketones on breath
• Dehydration
• Increased respiratory rate, tachycardia, hypotension
• Low grade infections, thrush/ balanitis


What are the signs of type 2 diabetes mellitus?

• Not ketotic
• Usually overweight but not always
• Low grade infections, thrush/ balanitis
• May have micro or macro-vascular complications


How is glucose controlled in health?

• Levels of glucose and other nutrients entering the blood vary markedly during the day
• But between a complete carbohydrate blowout and NO food ingested, blood glucose is maintained at a fairly tight range
• Insulin dominates the absorptive state, the only hormone which lowers blood glucose


What happens to glucose control in type 1 diabetes?

Beta cells are destroyed resulting in there being a decrease in the amount of beta cells which means insulin production goes down