6.1.1 Diabetes Type I Flashcards
What is insulin?
Protein secreted by beta cells
When is insulin secreted?
Increased glucose concentration
Incretin release e.g. glucagon like peptide (GLP-1) and gastric inhibitory peptide (GIP)
Parasympathetic activity via M3 receptors
What is the half-life of insulin?
5 minutes in plasma
What is insulin release inhibited by?
Low plasma glucose concentration
Cortisol
Sympathetic activity via alpha 2 receptors
What is the role of insulin?
Decrease hepatic glucose output via inhibition of gluconeogenesis and glycogenolysis- increases glycogen stores
Promotes glucose uptake into tissues- muscles and adipose especially
Why is insulin secreted into the blood even during fasting?
Prevents receptor down-regulation
When does insulin concentration increase?
Just after meals
What are the symptoms of type 1 diabetes?
Polyuria
Polydipsia
Weight loss
Fatigue/lethargy
Generalised weakness
Blurred vision
What are the diagnostic factors of type 1 diabetes?
Hyperglycaemia fasting glucose >6.9mmol/L
Random plasma glucose >11mmol/L
Plasma or urine ketones in presence of hyperglycaemia
HbA1c >48mmol/mol
Outline plasma glucose vs HbA1c
Glucose
Immediate measure of glucose levels in blood mmol/L
HbA1c
Glycated haemoglobin, percentage of RBCs with sugar coating
Reflects average blood sugar over last 10-12 weeks, mmol/mol
What is the biochemical triad for diabetic ketoacidosis?
Hyperglycaemia
Ketonaemia
Acidosis
When do you suspect DKA?
Blood glucose >11mmol/L
AND:
- Pear drop/acetone breath
- Vomiting + diarrhoea
- Confusion
- Visual disturbance
- Abdominal pain
How do you test for DKA?
Ketones in urine or blood
Venous pH < 7.3
HCO3 < 15mmol/L
What are the precipitating factors for DKA?
Infection
Trauma
Non-adherence to insulin treatment
Drug to drug interactions
How do you treat DKA?
IV fluids first
IV soluble insulin
K+ correction in additional fluids
What is the problem with bovine or procine insulin?
Difference in number of amino acids
Caused immune reaction as recognised as foreign to the body
Why must you give insulin paraenterally?
Protein
If given orally would be digested in the gut
What is the usual format of insulin?
100 units/ mL
In obesity and insulin resistance can be 300 and 500 units/mL
How is insulin administered?
Sub-cutaneous injection into upper arms, thighs, buttocks or abdomen
IV infusion for emergencies
Why do you want to slow down insulin absorption?
To allow insulin to circulate in the body, otherwise would get absorbed at injection site
How do you slow down absorption of insulin?
Protamine and/or zinc complex with natural insulins
Soluble insulins form hexamer, delays absorption from site of injection
Plasma concentration greatest 2-3 hours after dosing
Doses usually 15-30 minutes before meal
What is different about insulin analogues?
Different pharmacokinetics
Pharmacodynamics is still the same
Effect of drug is faster
Used in emergency IV infusions
Why do you need to rotate injection sites?
Limit lipodystrophy- loss of adipose tissue in the area
Why is non-adherence such an issue with insulin injections?
Need to take SEVERAL injections daily
Painful to inject
