what is DKA
an acute metabolic complication of Type 1 diabetes but can also occur in type 2 diabetes
- Metabolic acidosis- build up of acids in bloodstream
why does DKA occur and what can it lead it
occurs due to a lack of insulin
- counter regulatory hormones combined with insulin deficiency causes a cascade of problems
- can lead to shock, coma and death
- medical emergency
describe the impact of DKA
- Mortality risk is high but with appropriate urgent care, actual mortality is <1%
- mortality higher if older age and co-morbidities
- costly treatment
what are the features of DKA
- hyperglycaemia
- dehydration
- electrolyte losses
- ketogenesis
- acidosis
where is insulin secreted
secreted from beta cells in the islets of Langerhans of the pancreas
what are the major roles of insulin
- uptake and storage of glucose into cells to be used for energy
- uptake of fats to adipose tissue
- uptake of amino acids to muscle for protein synthesis
what is glycogen and what is its role
- a polysaccharide glucose polymer that is stored in the liver
- this stored energy source can be broken down and the glucose used later when energy is needed
- this breakdown is glycogenolysis
what is the relationship between insulin and glycogen
- insulin promotes synthesis of glycogen
- insulin blocks glycogenolysis
what is gluconeogenesis
- the formation of glucose in the liver from non carb sources
- this process is used along with glycogenolysis to increase blood sugar when glucose levels are low
what is the relationship between insulin and gluconeogenesis
insulin blocks gluconeogenesis
what is glucagon and what is its role
- a peptide hormone produced by alpha cells in the islets of langerhans
- glucagon opposes the effects of insulin
- will be secreted when blood glucose is low, when insulin is low and when fatty acid levels are low
- in diabetes, glucagon is still secreted
what is the relationship between insulin and glucagon
- insulins overall effect is to reduce blood sugar, glucagons overall effect is to increase blood sugar
- glucagon promotes glycogenolysis and gluconeogenesis
what occurs in the presence of insulin
- uptake of glucose from blood to cells to be used as energy
- uptake of esterified fatty acids to adipose cells
- glycogen synthesis in the liver
- gluconeogenesis inhibited
- glucagon secretion inhibited
- K+ uptake from blood to cells
- protein synthesis in muscle promoted
- renal excretion of sodium inhibited
what occurs in the absence of insulin
- glucose stays in blood and cells need alternative sources of energy
2.lipolysis occurs for energy - glycogenolysis and gluconeogenesis occurs
- glucagon secretion occurs
- K+ uptake from blood to cells is inhibited
- proteolysis occurs for energy
- renal excretion of sodium increases
why are ketones produced
- lipolysis releases glycerol and free fatty acids from lipid
- free fatty acids uptaken in liver and oxidised to acidic ketone bodies
- ketone bodies released to bloodstream and uptaken into cells for energy
why does acidosis occur
- ketones cause shift in acid base balance (drop in ph)
- excess acid (H+) drives the equation through carbonic acid
- lungs try to remove excess CO2
what are the acidosis effects
- respiratory centre in medulla tries to correct by removal of cO2
- patient hyperventilates - vasodilation occurs to increase oxygen delivery
- shock signs- catecholamines released, drowsiness, hypothermia, tachycardia, hypotension
what are the causes of DKA
- acute infections
- omitting insulin
- major trauma
- major CV event
- new diagnosis of type 1 diabetes, especially in younger children
- other factors such as pregnancy, chronic liver disease, heavy alcohol use
describe the diagnostic criteria Of DKA
- blood glucose above 11mmol/l
- blood ketones above 3mmol/l or urine ketones at least ++
- blood pH under 7.3/bicarbonate under 15mmol/l
- other common signs such as drowsiness, vomiting, headache, dehydration, ketone smell
what is the ketone smell
characteristic scent described as sweet, fruit, like acetone
what is the immediate treatment for DKA
- Give fixed rate insulin infusion- 50 units human soluble insulin made up to 50ml with 0.9% NaCL solution
- give 1000ml of 0.9% NaCl over 60 mins for fluid replacement
- replace potassium
- assess patient- respiratory rate, blood pressure, pulse, oxygen saturation
