L17 - Acute complications of diabetes Flashcards
Insulin levels in diabetic keto-acidosis
- Absolute insulin deficiency
Insulin levels in hyperosmolar hyperglycaemia state
- Relative insulin deficiency
What is hyperosmolar hyperglycaemia state
Hyperosmolar hyperglycemic state (HHS) is a complication of diabetes mellitus in which high blood sugar results in high osmolarity without significant ketoacidosis
Symptoms of hyperosmolar hyperglycaemia state
Symptoms include signs of dehydration, weakness, legs cramps, vision problems, and an altered level of consciousness.
Insulin levels in hypoglycaemia
- Relative insulin excess
Effects of insulin deficiency
- Glycogenolysis
- Glucagon, adrenaline(cortisol) release
- Lipolysis and reduced esterification of fatty acids
How does lipolysis and reduced esterification of fatty acids increase hepatic glucose output and cause hyperglycaemia
–> NEFA –> Ketones –> acetone, acetoacetate, hydroxybutyrate
–> glycerol –> gluconeogenesis –> increase in hepatic glucose output and hyperglycaemia
How does proteolysis and reduced uptake of amino acids increase hepatic glucose output and cause hyperglycaemia
Proteolysis and reduced uptake of amino acids –> alanine –> gluconeogenesis –> increase in hepatic glucose output and hyperglycaemia
What causes hyperglycaemia in diabetic ketoacidosis
- Unchecked gluconeogenesis
What causes osmotic diuresis in diabetic ketoacidosis
- Dehydration
What causes ketpsis in diabetic ketoacidosis
- Unchecked ketogenesis
What cases anion-gap metabolic acidosis in diabetic ketoacidosis
- Dissociation of ketone bodies into hydrogen ion and anions
How can insulin deficiency lead to CV collapse
Insulin deficiency –> hyperglycaemia –> glycosuria –> dehydration –> renal failure –> shock –> CV collapse
Insulin deficiency –> lipolysis –> increase in FFAs –> ketones –> acidosis –> CV collapse
Physiological effects of insulin deficiency in adipose tissue
• Increased lipolysis and reduced esterification of fat
• Insulin deficiency
• Glucagon/adrenaline excess
Results in excess FFA and glycerol from breakdown triglycerides
• FFA substrate for hepatic synthesis of ketone bodies
• Acetoacetate/Hydroxybutyrate – strong organic acids
• (Acetone)
• Rate of ketogenesis is linked to rate of gluconeogenesis
• Muscle and brain can utilise ketones as main energy substrate
What causes ketoacidosis
- Ketoacidosis results when ketone body production exceeds rate of utilisation in peripheral tissues (brain and muscle) and renal clearance
How does insulin deficiency give rise to nausea and abdo pain
Lipolysis and reduced esterification of fatty acids –> NEFA –> Ketones –> acidosis –> nausea, abdo pain
How does insulin deficiency cause dehydration
Increased hepatic glucose output and hyperglycaemia –> osmotic diuresis –> dehydration
How is acidosis in diabetic ketoacidosis managed
• Intracellular buffering - H+ / K+ exchange
○ Potassium hydrogen ion pump
• Respiratory compensation – hyperventilation
○ H+ stimulates respiratory centres
○ Breathe off CO2 (H+ + HCO3- H2O + CO2)
• Renal excretion of H+ (slow response)
Electrolyte disturbances in diabetic ketoacidosis
- Potassium depletion - maybe > 250 mmol
- Sodium depletion
- Dehydration
Main differences between cation concentrations between ECF and ICF
- Higher Na+ concentration in interstitial fluid
- Higher K+ concentration in ICF(muscle) - this is due to intracellular buffering - H+/K+ exchange
Age most affected by diabetic ketoacidosis
- Mostly young T1DM
Precipitating causes of diabetic ketoacidosis
- Relative or absolute insulin deficiency