What is Diabetes Mellitus? Flashcards
Diabetes Mellitus
“a group of metabolic diseases of multiple aetiologies characterised by hyperglycaemia together with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action, or both”
What are the symptoms of hyperglycaemia?
- Polydipsia
- Polyuria
- Blurred vision
- Weight loss
- Infections
What are the possible long term complications of hyperglycaemia?
Microvascular
- Retinopathy
- neuropathy
- Nephropathy
Macrovascular
- Stroke
- MI
- PVD
What metabolic decompensation can occur with hyperglycaemia?
DKA
HHS
How is diabetes diagnosed?
- Diagnostic glucose levels (venous plasma) fasting >7.0 mmol/l, random >11.1 mmol/l
- OGTT 2h after 75g CHO >11.1 mmol/l
- Diagnostic HbA1c ≥ 48 mmol/mol.
What is considered intermediate hyperglycaemia?
- Impaired fasting glucose 6.1-7 mmol/l
- Impaired glucose tolerance 2h glucose ≥7.8 and <11mmol/l
- HbA1c 42-47mmol/mol
What do diabetes diagnostic criteria identify?
A group with significantly increased premature mortality and increased risk of microvascular and cardiovascular complications
What does intermediate hyperglycaemia identify?
Identifies a group at higher risk of future diabetes and adverse outcomes such as cardiovascular disease
Normoglycaemia
Glucose levels associated with low risk of developing diabetes or cardiovascular disease
What is required for a definitive diagnosis of diabetes?
- ONE diagnostic lab glucose plus symptoms
- TWO diagnostic lab glucose or HbA1c levels without symptoms.
What is HbA1c?
Glycated haemoglobin
What does HbA1c give an indication of?
Blood glucose levels over last 8-12 weeks
When can HbA1c not be used for diagnosis?
-Children and young people.
-Pregnancy—current or recent (< 2 months).
-Short duration of diabetes symptoms.
-Patients at high risk of diabetes who are acutely ill
(HbA1c ‡ 48 mmol⁄ mol confirms pre-existing diabetes, but a value < 48 mmol ⁄ mol does not exclude it and such patients must be retested once the acute episode has resolved).
-Patients taking medication that may cause rapid glucose rise; for example, corticosteroids, antipsychotic drugs (2 months or less).
-Acute pancreatic damage or pancreatic surgery.
-Renal failure.
-HIV
How can diabetes be classified?
- T1DM
- T2DM
- Other types
What is normal metabolism?
Levels of glucose and other nutrients entering the blood vary markedly during the day but, between a complete carbohydrate blow-out and NO food ingested, [BG] is maintained over a fairly tight range
What dominates the absorptive state?
Insulin
What is the only hormone which lowers [BG]?
Insulin
What role do a-cells play in [BG] control?
- a-cells secret glucagon
- Stimulation of the liver (glycogenolysis and gluconeogenesis)
What role do B-cells play in the[BG] control?
- B-cells secrete insulin
- Insulin involved in glucose uptake in adipose, liver and skeletal muscle
What are the genetic linked risks of developing T1DM?
- Monozygotic twins 30-50% concordance
- If father has Type 1: 6% risk
- If mother has Type 1: 1% risk
- If sibling has Type 1: 8% risk
- If non-identical twin has Type 1: 10% risk
- If both parents have Type 1: 30% risk
What does development of T1DM require?
Genetic pre-disposition plus
- Trigger e.g.? Viral infection
- Auto immunity
What effect does insulin have on adipose tissue?
Reduced lipolysis
What effect does insulin have on the liver?
Reduced glucose production
What effect does insulin have on muscle?
Increased glucose uptake
How does insulin cause stimulation?
It binds to receptors on cell surfaces and controls a range of intracellular processes
What is T1DM characterised by?
Insulin deficiency
What can hyperglycaemia lead to in T1DM?
- Ketoaemia
- DKA
In T1DM presentation, what may there be a short history of?
- Thirst
- Tiredness
- Polyuria / nocturia
- Weight loss
- Blurred vision
- Abdominal pain
What might be found on examination of T1DM?
- Ketones on breath
- Dehydration
- May have increased respiratory rate, tachycardia, hypotension.
- Low grade infections, thrush / balanitis
What are the genetic linked risks of developing T2DM?
- Identical twin: 90-100% risk
- One parent: 15%
- Both parents: 75%
- Sibling: 10%
- Non-identical twin: 10%
What is the pathophysiology of T2DM?
- May initially have hyperinsulinaemia but there is a progressive decrease in insulin production
- Increased cellular insulin resistance
- Altered lipolysis
- Increased glucose production
- Reduced glucose uptake
What are the symptoms of T2DM?
- May have no symptoms
- Thirst
- Tiredness
- Polyuria / nocturia
- Sometimes weight loss
- Blurred vision
- Symptoms of complications e.g. CVD
What are the signs of T2DM?
- Not ketotic
- Usually overweight but not always
- Low grade infections, thrush / balanitis
- In type 2 DM may have micro vascular or macrovascular complications at Dx
When screening for T2 diabetes in asymptomatic populations what risk factors are loked at?
Risk factors—any two present
• Overweight
• Family history
• Over age 30 years if Maori ⁄ Asian (Indian subcontinent)
⁄ Pacific Island descent
• Over age 40 years if European
• Previous history of diabetes in pregnancy (Gestational Diabetes)
Had a big baby (more than 4 kg)—not in immediate post-natal period
• Inactive lifestyle, lack of exercise
• Previous high blood glucose ⁄ impaired glucose tolerance
What ‘other’ types of diabetes are there?
- Recognised genetic syndromes :MODY
- Gestational diabetes
- Secondary diabetes
What is MODY?
Maturity Onset Diabetes in the Young which is an autosomal dominant condition which leads to impaired beta cell function
What causes MODY?
Single gene defect
How proportion of diabetes cases does MODY account for?
5%
What is it important to do when someone is diagnosed with diabetes?
Take a family history
Describe MODY due to glucokinase mutations.
- Onset at birth
- Stable hyperglycaemia
- Diet treatment
- Complications rare
Describe MODY due to transcription factor mutations.
- Adolescence/young adult onset
- Progressive hyperglycaemia
- 1/3 diet, 1/3 OHA, 1/3 Insulin
- Complications frequent
How is secondary DM treated?
Drug therapy such as corticosteroids
What can cause pancreatic destruction in secondary diabetes?
- Haemochromatosis- excess iron deposition
- Cystic fibrosis
- Chronic pancreatitis
- Pacreatectomy
What can cause secondary diabetes?
- Pancreatic destruction
- Recognised genetic syndromes= DIDMOAD
- Rare endocrine disorders (Cushing’s syndrome, acromegaly, pheochromocytoma)
What is gestational diabetes?
Hyperglycaemia of pregnancy
What is gestational diabetes associated with?
-Family history of T2DM
When does gestational diabetes develop?
2nd or 3rd trimester
What does gestational diabetes increase the mothers risk of?
Increased risk of T2DM later in life
When is gestational diabetes more common?
When the mother is overweight and inactive
What problems can gestational diabetes cause in the neonate?
- Macrosomia
- Respiratory distress
- Neonatal hypoglycaemia
