Lecture 8 What is Diabetes Mellitus Flashcards
Define diabetes
A group of metabolic diseases of multiple causes 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 molecular decompensation are involved in hyperglycaemia
DKA HHS
What are the long term complications of hyperglycaemia
Retinopathy Neuropathy Nephropathy Stroke MI PVD
Normal fasting plasma glucose
=/<6
Intermediate fasting plasma glucose
6.1-6.9
DM fasting plasma glucose
=/>7
Random plasma glucose that would suggest DM
> /=11.1
Normal 2 hour OGTT value
=7.7
Intermediate 2 hours OGTT value
7.8-11
DM 2 hour OGTT value
> /=11.1
Intermediate hyperglycaemia in HbA1c
HbA1c 42-47mmol/mol
Advantages of testing glucose
Established method
Smaller variation between laboratories
More feasible in developing countries
Directly measures molecule thought to cause diabetic complications
Disadvantages of testing glucose
Requires a fasting
May require OGTT
Higher variability within individuals
Advantages of testing HbA1c
No need for fasting sample
More stable after collection
Marker of glyceamic control
Lower variability within individuals
Disadvantages of testing HbA1c
Measurement can be misleading due to haemoglobinopathies, anaemia or renal failure
May differ with age and ethnicity
More costly
Surrogate marker of hyperglycaemia
When HbA1c cannot be used for diagnosis
- All children and young people
- Pregnant or recently pregnant
- Short duration of diabetes symptoms
- Acutely ill patients
- HbA1c >48mmol/mol = pre-existing diabetes, nut value below this does not exclude it- patient must be retested once acute episode has resolved
- Taking medication that causes rapid rise in glucose- corticosteroids, antipsychotic drugs
- Acute pancreatic damage or pancreatic surgery
- Renal failure
- HIV
What is the risk of an individual if their father has type 1 DM
6%
What is the risk of an individual of their mother has type 1 DM
1%
What is the risk of an individual if both parents have type 1 DM
30%
What is the risk of an individual if their non-identical twin has type 1 DM
30%
Aetiology of type 1 diabetes
- Genetic predisposition
- Trigger e.g. viral infection
- Auto immunity
Clinical presentation of type 1 diabetes on short duration
- Thirst
- Tiredness
- Polyuria/nocturia
- Weight loss
- Blurred vision
- Abdominal pain
Clinical presentation of type 1 diabetes on exmination
- Ketones on breath
- Dehydration
- May have increased respiratory rate, tachycardia, hypotension
- Low grade infections, thrush, balanitis (diaper rash)
What is insulin
- Protein consisting of alpha(21) and beta(30) chains
* Linked together with disulphide bonds
What is the risk of an individual for type 2 diabetes if their twin has it
90-100%
What is the risk of an individual for type 2 diabetes if one parent has it
15%
What is the risk of an individual for type 2 diabetes if both parents have type 2 diabetes
75%
What is the risk of an individual for type 2 diabetes if their sibling has type 2 diabetes
10%
What is the risk of an individual for type 2 diabetes if their non-identical twin has type 2 diabetes
10%
Symptoms of type 2 diabetes
- May have no symptoms
- Thirst
- Tiredness
- Polyuria/nocturia
- Sometimes weight loss
- Blurred vision
- Symptoms of complications e.g., CVD
Signs of type 2 diabetes
- No ketotic
- Usually overweight but not always
- Low grade infection, thrush/balanitis
- May have microvascular complications and Dx
Screening for Diabetes in asymptomatic patients
• All eligible adults aged 40 and over, except pregnant women
• People aged 25-39 of south Asian, Chinese, African-Caribbean, Black African and other high risk black and minority ethnic groups except pregnant women
• Adults with conditions that increase risk of type 2 diabetes
CV disease
Hypertension
Obesity
Stroke
PCOS
History of gestational diabetes
Mental health problems
Name other types of DM
- MODY: Maturity Onset Diabetes in the Young
- Gestational diabetes
- Secondary diabetes
What is the cause of MODY
Autosomal dominant
5% of people with diabetes
Impaired beta-cell function
Single gene defect
Glucokinase mutations- onset at birth, stable hyperglycaemia, diet treatment, complications rare
Transcription factor mutations (HNF-1a, HNF=1b, HNF-4a). Adolescence/youg adult onset, progressive hyperglycaemia, 1/3 diet, 1/3 OHA, 1/3 insulin. Complications frequent
What is gestational diabetes associated with
Increasing insulin resistance in pregnancy
Associated with FH of type 2 diabetes
Increased risk of type 2 diabetes later in life
Develops 2nd/3rd trimester
More common if overweight and inactive
What are neonatal problems in gestational diabetes
macrosomia (newborn who’s significantly larger than average), respiratory distress, neonatal hypoglycaemia
Name causes of secondary diabetes
Any major disease of the exocrine pancreas – Chronic pancreatitis – Haemochromatosis – Cystic fibrosis Endocrinopathies – Acromegaly – Cushing’s syndrome – Glucagonoma – Pheochromocytoma Drug or chemical induced diabetes – Steroids
