Question: What are the major risks associated with diabetes and surgery?
- Increased perioperative risk due to co-morbidities, largely vascular
- Microvascular - nephropathy, retinopathy
- Macrovascular - increased rate of atherosclerosis
- Complex polypharmacy
- Increased risk of infective complications
- Risk of hyperglycaemia - normal metabolic response to surgical stress is lipolysis, glucose mobilization, and increased insulin production to maintain normoglycaemia. Diabetics have an absent/inadequate insulin response, leading to hyperglycaemia with or without ketoacidosis. This response is exaggerated in infection or sepsis
Question: How should diabetes be managed in the surgical patient?
- Approach depends on whether diet, tablet, or insulin controlled, magnitude of anticipated surgical stress, presence of sepsis, and starvation time:
- Elective patients
- Develop individual care plan based on local guidelines
- Manage lifestyle in advance - diet, exercise, alcohol intake
- Establish tight control prior to surgery
- Minimize starvation time
- Variable rate intravenous insulin infusion for patients missing more than one meal
- Hourly glucose monitoring during procedure and immediately afterward, aim 6-10mmol/L
- Enhanced recovery principles to return to normal eating and insulin/tablet regime early
- Emergency patients
- Measure HbA1c to establish degree of control
- Closely monitor glucose, if >10mmol/L initiate variable rate insulin infusion to continue until eating and drinking.
- Involve critical care and specialist diabetic team early
Question: What is diabetic ketoacidosis?
- Insufficient insulin to allow glucose to enter cells, therefore they switch to breaking down fatty acids, with the byproduct of ketones
- Usually occurs in type 1 diabetics, rarely in insulin dependent type 2
Question: What are the symptoms of diabetic ketoacidosis?
- Deep, laboured (kussmaul) breathing, or tachypnoea
Question: What investigations should you do?
- Urinary and serum ketones
- Serum blood glucose - serial hourly measurement
- Arterial blood gases - for pH, anion gap, bicarbonate
- Serum electrolytes
- Full blood count (to look for precipitating infection)
- CT/MRI imaging if altered consciousness
Question: What is the management of DKA?
- Primary fluid management - isotonic saline, not too rapid unless circulatory collapse
- Early discussion with medical/diabetic team
- Insulin infusion - fixed rate or variable, depending on medical advice
- When serum glucose falls to 10-15mmol/L introduce glucose containing fluids (no more than 2L/24h) so that insulin infusion can continue
- Replace potassium (increased cellular uptake with insulin)
- Consider urinary catheter
Question: What are the complications of DKA?
Hyperglycaemic Hyperosmolar Non Ketotic Acidosis (HONK) / Hyperosmolar Hyperglycaemic State (HHS)
Question: What is HONK/HHS?
- Raised blood glucose (>30mmol/L) in type 2 diabetics can lead to a hyperosmotic state
- It can be due to not taking medications, illness/surgical insult, undiagnosed type 2 diabetes
What are the clinical features of HONK/HHS
- Extreme thirst
- Frequent need to urinate
What is the management of HONK/HHS
- Frequent serum glucose monitoring
- Intravenous fluid (normal saline) is the primary intervention
- Fixed rate insulin infusion if glucose fails to normalise with fluid replacement alone
- Continue insulin until eating and drinking