glucose Flashcards
What is the blood glucose level in hypoglycemia for adults?
No consensus
Usually below 4 mmol/L
In adults - <3-3.5
In newborns <2.5
But you can be okay at low levels too so symptoms matter
Symptoms of hypoglycemia
Adrenergic - tremors, palpitations, sweating, hunger
Neurohypoglyemic symptoms - somnolence, confusion, incoordination, seizures, coma
Sometimes asymptomatic - loss of hypoglycemia
What happens when we have low blood sugar?
You stop producing insulin and produced glucagon
You reduce peripheral (non-essential) uptake of glucose
Increased glycogenolysis and gluconeogenesis
Increase lipolysis
What does lipolysis result in?
Increased free fatty acids through beta oxidation
Product = ketone bodies
When does lipolysis occur?
Only if there is no insulin.
How does the hypothalamus respond to hypoglycemia?
Sympathetic activation
????
What do you do to investigate hypoglycemia?
Confirm there is hypoglycemia - this is easier in patients with diabetes, not in patietns without
If not you have to bring them in and monitor blood glucose during fasting in clinic
Venous glucose vs capillary blood glucose
capillary blood glucose - point of care analyser, but it’s not very precise at low blood sugar levels, not quality controlled
Venous glucose measurement is better
What is added to the preservative
Fluoride oxalate
Causes of this without diabetes
Fasting/reactive
Critically unwell
Organ failure - particulalry liver failure as they can’t store glycogen
gluconeogenesis occurs in kidneys
Post-gastric bypass
Drugs
Extreme weight loss
Factititious
Paeds vs adult??
Reasons for hypoglycemia in diabetes
Sulphonylureas
Gliclazide
Medications
Missed meals
Excessive alcohol
Strenuous exercise
Co-existing autoimmune conditions e.g. addisons (rare) - do a short synacthen test
Medications that can cause hypoglycemia in diabetic patietns - and when
Sulphonylureas
Meglitinides
GLP-1 agonists - only when given in conjunction with INSULIN
Insulin - if there is a mismatch between carbs and insulin
Alcohol
Causes of hypoglycemia outside of diabetes?
Insulin levels
C-peptide
Drug screen
Auto-antibodies
Cortisol/GH
FFA/ketones
Lactate
What is c-peptide?
It’s a marker of how much insulin the PANCREAS is making
Pro-insulin gets cleaved into pro-insulin and C-peptide
What are the combinations of scenarios you can get from insulin/hypoglycemia?
Hypoglycemia hypoinsulinemia
Hyperinsulinemic hypoglycemia, high c-peptide
High insulin and low c-peptide from exogenous insulin
What is the appropriate diabetic response?
Hypoglycemic hypoinsulinemia
Neonatal hypoglycemia
In inherited metabolic disorders, you might get fatty acid oxidation defect so you might measure this too - see slide
List of conditions causing inappropriately high insulin
Islet cell tumours - insulinoma
Drugs - insulin, sulphonylurea
Islet cell hyperplasia (Beckwith Weidermann syndrome, Nesidioblastosis, infant of a diabetic mother)
the excessively high insulin causes
When someone has high insulin and high c-peptide, what do you need to check?
Do a sulphonyl urea drug screen and make sure that isn’t causing the hyperinsulinemia
How does sulphonylurea
Insulinoma is associated with which syndrome?
MEN1
Normally if c peptide and insulin are low, what happens to free fatty acids?
They should be high
What happens
Non-islet cell tumour hypoglycemia
big IGF-2 - an aberrant protein which binds to the insulin receptor, as though insulin is being produced,
presents in patients with lung cancers and epithelial cells
it’s a paraneoplastic syndrome
Genetic causes of hyperinsulinism
Glucokinase activating mechanism
see slide
reactive post-prandial hypoglycemia
Due to
Why does gastric bypass surgery cause
islet cells hyperplasia
19 yo girl, lenugo hair on back, low BMI, BM of 2.5, what’s the cause?
Low glycogen stores as a result of starving
