Diabetes: Insulins and oral hypoglycaemic agents Flashcards
Give a brief outline of insulin
Protein secreted by B cells in pancreas
STIMULATED BY:
Secreted in response to raised glucose levels
Increased by incretins (glucagon like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP)
Parasympathetic activity (M3 receptors)
INHIBITED BY:
Low glucose levels
Cortisol (stress hormone thus don’t want to decrease glucose levels)
Sympathetic activity (alpha-2)- increase glucose availability thus inhibit insulin release
Briefly describe the role of insulin
- Decreases hepatic glucose output via inhibition of gluconeogenesis
- Inhibits glycogenolysis
- Promotes uptake of fats
Describe the normal daily profile of plasma insulin levels
- Normally maintained at a basal level
- Spikes around meal times
Treatment of diabetes involves replicating these typical insulin spikes alongside a basal level of activity
Provide a definition for diabetes and list some common symptoms experienced by patients
Hyperglycaemia; random plasma glucose > or equal to 11 mmol/L
Single raised plasma glucose without symptoms not sufficient for diagnosis
Symptoms present due to alterations in palsma glucose levels and hence osmolarity
- Polyuria
- Polydipsia
- Weight loss
- Fatigue/lethargy
List some risk factors for developing diabetes
- Obesity (more fat leads to insulin resistance)
- Family Hx
- Ethnicity
- Diet
- DRUGS; thiazide/thiazide-like diuretics, glucocorticoids, B-blockers – all increase glucose levels (pt in pre-diabetic state whilst on these meds)
What does the HbA1C show?
Glycated haemoglobin
% of RBCs with sugar coating
Reflects average blood sugar over the last 10-12 wks; mmol/mol (or %)
(IMMEDIATE MEASURE OF BLOOD GLUCOSE LEVELS- mmol/L)
Why must insulin be given parenterally?
It is a protein, thus must be given parenterally to avoid digestion in the gut
Hence, given as subcutaneous injections daily/IM/IV infusion (emergency)
Give the standard insulin dosing and formulation
Usually formulated in 100 U/mL – UNITS PER ML
Larger doses available to reduce volume; 300 and 500 U/mL; (in obesity, insulin resistance where higher doses of insulin are required)
Give some modes of delivery of insulin
- Routine delivery by SC injection into upper arms/thighs/buttocks/abdomen
- IV infusion- emergency treatment
Why is a dose of insulin taken 15-30 mins prior to a meal?
As the greatest plasma concentration of insulin is after 2-3 hrs of dosing
How would you describe the structure of insulin?
Hexamer
Why are protamine and/or zinc sometimes given with insulin?
To modify insulin absorption
As protamine/ zinc can increase or decrease breakdown rate of the insulin hexamer
Alllows for short or long acting effects of insulin
What is lipodystrophy?
Atrophy/hypertrophy of adipose tissue at insulin injection sites
Thus, is important to rotate the sites of administration
List the main insulin analogues and their class (ie rapid, short, intermediate or long acting)
- Insulin aspart - RAPID
- Soluble insulin; Humulin S, Actrapid - SHORT
- Isophane insulin (NPH) - INTERMEDIATE
- Insulin glargine - LONG
Which insulin analogue is given in an emergency (eg ketoacidotic crisis)?
IV soluble insulin
List some insulin prescriptions
- Syringes
- Pens
- Pumps
- (inhalers)
Give some warnings/contraindications of taking insulin
- Hypoglycaemia
- Lipohypertrophy, lipoatrophy (at injection site)
- Renal impairment - risk of hypoglycaemia (as renal clearance of insulin)
Give some important interactions/considerations of insulin
- Other hypoglycaemic agents- caution
- Increased dose with steroids
Describe basal-bolus dosing
- Rapid acting bolus - aspart (at meal times)
- Long acting basal - glargine (maintenance throughout the day)
Tailored to patients
Define diabetic ketoacidosis (DKA)
- Hyperglycaemia
- Acidosis
- Ketonaemia
Pear drops fruity breath smell
DKA may present with low blood ketones
Hyperglycaemia may not always be present (in some pt’s)
When should you suspect DKA?
- Blood glucose greater than 11 mmol/L
- Infection
- Stress/trauma
- Poor insulin adherence
- Adverse drug reactions
- Ketosis
Outline the treatment for DKA
- Fluids priority, then insulin
- Glucose
- K+ (as stat dose of insulin)
Fluids - due to diuresis from raised glucose levels
Insulin - IV (or IM dose of insulin)
Glucose - due to hypoglycaemic state from insulin
K+ - due to hypokalaemia (masked)
Why do you need to give K+ in DKA despite a high measured blood K+ level?
Due to a large dose of insulin given, the patient has hypokalaemia - thus the total blood K+ levels are low in DKA
However, K+ levels in the blood may be high due to the acidosis that is also present
Thus, the total blood K+ levels are low, but are measured as being high due to the acidosis (reciprocal cation shifts)