Lecture 19: What is Diabetes Mellitus Flashcards
symptoms of hyperglycaemia
- polydipsia
- polyuria
- blurred vision
- weight loss
- infections
hyperglycaemia long-term complications
- microvascular > retinopathy, neuropathy, nephropathy
- macrovascular > stroke, MI, PVD
discuss diabetes diagnosis
- diagnostic glucose levels (venous plasma): fasting >/= 7.0mmol/l, random >/= 11.1mmol/l
- oral glucose tolerance test (OGTT) 2h after 75g CHO >/= 11.1mmol/l
- diagnostic HbA1C >/= 48mmol/mol
- ONE diagnostic lab glucose or HbA1c PLUS SYMPTOMS
- **TWO **diagnostic lab glucose or HbA1c levels without symptoms
intermediate hyperglycaemia lab levels
- impaired fasting glucose 6.1-7mmol/l
- impaired glucose tolerance 2h glucose >/= 7.8 and < 11mmol/l
- HbA1c 42-47mmol/mol
definition of 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”
Type 1 diabetes is characterised by insulin deficiency, causing….
list
- hyperglycaemia, ketonaemia > diabetic ketoacidosis
- increased lipolysis
- raised glucose production
- reduced glucose uptake
genetic risk of developing type 1 diabetes based on family members affected
- identical 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
symptoms and signs of type 1 diabetes
short duration of:
- thirst
- tiredness
- polyuria/nocturia
- weight loss
- blurred vision
- abdominal pain
on examination:
- ketones on breath
- dehydration
- may have increased RR, tachycardia, hypotension
- low grade infections, thrush, balanitis
what tests are performed later to confirm a clinical diagnosis of type 1 diabetes?
- autoantibodies: GAD, IA2, ZNT8; usually take 6 weeks to come back so would not wait for this to make a diagnosis.
- C-peptide: usually only reliable 3 years after diagnosis, would expect undetectable c-peptide in someone with longstanding t1D, low levels in more recently diagnosed. High C-peptide levels would not indicate t1D.
- Genetics t1 genetic risk score - not used routinely, can be helpful if diagnosis unclear.
genetic risk of developing type 2 diabetes based on family members affected
- identical twin 90-100%
- one parent 15%
- both parents 75%
- sibling 10%
- non-identical twin 10%
symptoms and signs of type 2 diabetes
symptoms:
- may be asymptomatic
- thirst
- tiredness
- polyuria/nocturia
- sometimes weight loss
- blurred vision
- symptoms of complication e.g. CVD
signs:
- not ketotic
- usually overweight
- low-grade infections, thrush/balantis
- may have microvascular or macrovascular complications at diagnosis
type 2 diabetes risk factors
- 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 4kg)- not in immediate post-natal period
- inactive lifestyle, lack of exercise
- previous high blood glucose/impaired glucose tolerance
features of monogenic diabetes (MODY):
- maturity onset diabetes in the young (MODY)
- autosomal dominant impaired beta-cell function
- single gene defect
- can be caused by glucokinase mutations or transcription factor mutations
compare monogenic diabetes caused by glucokinase mutations compared to transcription factor mutations
glucokinase mutations:
- onset at birth
- stable hyperglycaemia
- diet treatment
- complications rare
transcription factor mutations ((HNF-1alpha, HNF-1beta, HNF-4alpha):
- adolsecence/young adult onset
- progressive hyperglycaemia
- 1/3 diet, 1/3 OHA, 1/3 Insulin
- complications frequent
list the causes of secondary diabetes mellitus
- drug therapy e.g. corticosteroids
- pancreatic destruction: haemochromatosis, cystic fibrosis, chronic pancreatitis, pancreatectomy
- recognised genetic syndromes - DIDMOAD
- rare endocrine disorders e.g. Cushings syndrome, acromegaly, pheochromocytoma
