Diabetes
How should I approach reviewing a patient with diabetes in the Preadmission clinic?
Firstly, you will need to clarify the type of diabetes. This is because the type of diabetes determines perioperative management.
Type 1 diabetes is associated with autoimmune destruction of insulin secreting pancreatic beta cells, resulting in insulin deficiency
Type 2 diabetes is associated with reduced capacity to secrete insulin and insulin resistance.
Other things to evaluate are:
medications
compliance
home BGL measurements if known
HbA1c Level
presence of diabetic complications such as nephropathy, neuropathy, retinopathy
Is there anything else that I should do?
Patients with diabetes are at higher risk for negative perioperative outcomes. Lifestyle advice that you can provide to help improve perioperative outcomes are:
Smoking cessation
Exercise
Weight loss
Good nutrition
Decrease alcohol consumption
In order to promote good glycemic control, diabetic patients should be placed first on the theatre list. This will help decrease fasting time and decrease interruption to their normal diabetic medication regime.
#TIP If a patient has diabetes, and is not placed first on the morning theatre list, consider discussing this with your Senior
What is the significance of HbA1c Level?
HbA1c is glycosylated hemoglobin. It provides an indication on blood glucose level control over the past 2 to 3 months. The HbA1c goal for patients with diabetes is 6.5 to 7 percent. High preoperative HbA1c is associated with worse postoperative outcomes. Australian Diabetes Society Guideline recommends that a preoperative HbA1c of 9%, should lead to strong consideration for postponement of surgery. Endocrinologist should be referred for optimization.
#TIP 1 In your review, if you come across a patient with a high HbA1C >9%, be sure to discuss this with your Senior
#TIP 2 HbA1c should be repeated if not performed within the past 3 months
BGL range during the Perioperative period
UK Perioperative care for People with Diabetes Mellitus undergoing Elective and Emergency surgery guideline, recommend a Perioperative BGL target of 6 mmol/l to 12 mmol/l.
Preoperative Management of Type 2 Diabetes
One of the most important jobs, when reviewing Type 2 Diabetes patients in the Preadmission clinic is medication reconciliation; deciding which medications should be continued and which ones should be stopped.
Metformin
Mech of action: inhibits hepatic glucose formation. Also increases uptake of glucose by fat and muscle.
What to watch out for: the main concern is lactic acidosis (although this is rare!)
What to do: Metformin should be HELD on day of surgery
Sulfonylurea (example Gliclazide, Glimepiride)
Mech of action: increases release of insulin
What to watch out for: hypoglycemia
What to do: Sulfonylurea should be HELD on day of surgery
Sodium-glucose co-transporter 2 inhibitors (SGLT-2 inhibitors) (examples: Dapagliflozin, Empagliflozin)
Mech of action: increases the excretion of glucose and sodium into urine
What to watch out for: Euglycemic diabetic ketoacidosis
There have been cases of type 2 diabetic patients on SGLT-2 inhibitors who develop severe diabetic ketoacidosis with blood glucose levels in the normal range. Thankfully, this is uncommon.
What to do: SGLT-2 inhibitors should be HELD at least 2 days before surgery (including on day of surgery)
Glucagon-like peptide-1 analogues (GLP-1 agonists) (examples Dulaglutide, Exenatide)
Mech of action: decreases appetite, reduces glucagon release, increases glucose-dependent insulin excretion
What to watch out for: no serious side-effects to look out for
What to do: GLP-1 agonist can safely CONTINUE
Dipeptidyl peptidase‑4 inhibitors (DPP-4 inhibitors) (example Saxagliptin, Linagliptin)
Mech of action: prevents the breakdown of glucagon like peptide, thus increasing insulin secretion
What to watch out for: no serious side-effects to look out for
What to do: DPP-4 inhibitors can safely CONTINUE
Preoperative Management of Type 1 Diabetes
Insulin infusion
Patients with type 1 diabetes, who undergo big surgery (e.g. Renal transplant, Coronary artery graft surgery) are usually treated with variable rate intravenous insulin infusion. The aim of insulin infusion is to administer insulin at a variable rate, in order to maintain BGL target range between 6 to 10mmol/l. IV fluid, such as 5% dextrose in 0.45% sodium chloride, is also administered to provide maintenance fluids.
Hourly BGL is performed when Insulin infusion is used. The rate and amount of insulin infusion is determined by the patient's BGL and adjusted according to the algorithm. Each hospital will have their own algorithm to titrate rate of insulin infusion. Insulin infusion should be used in the preoperative setting (before surgery begins) as well as in the postoperative setting (until the patient is able to eat adequately).
How do I manage the patient’s own insulin?
For patients on long acting insulin (eg Lantus, Humulin, Levemir)
ONCE Daily (morning)
Give 80% of normal dose if on morning list
Give 80% of normal dose if on afternoon list
ONCE Daily (evening)
Give normal dose if on morning list
Give normal dose if on afternoon list
There is a variety of different insulin products eg (Premixed Insulin: Novomix, Humalog) (Short acting Insulin: Actrapid, Novorapid) and with varying dosing times (e.g. twice daily, three times daily).
#TIP Because of insulin complexity, Seek Pharmacist advice!
Common Clinical Short Calls - Hypoglycemia
You are the Night intern. You receive a call from the nursing staff that Mr A, who is day 2 post-op following radical cystectomy is hypoglycemic with BGL of 3.2 mmol. He has type 2 diabetes and is managed on oral medications only. How do you manage this?
Hypoglycemia is defined as BGL < 4 mmol.
Reasons for hypoglycemia in type 2 diabetic patient:
Medication related (was there a drug error made? Was Mr A restarted on medications too soon?)
Inadequate food intake (eg Did Mr A miss dinner? Was he eating poorly all day? Was he suffering from nausea and vomiting?)
Increased activity levels
Symptoms of Hypoglycemia:
Adrenergic related: tachycardia, sweating, tremor
Brain related: confusion, decreased consciousness, fatigue
If patient is alert:
Solve this problem by giving the patient something sugary! For example- Juice, Jelly beans, Biscuits etc
Next, repeat BGL 15 mins later. Aim to have BGL above 4.0mmol/L.
Afterwards, give the patient a small meal- eg peanut butter sandwich.
It would also be prudent to put Mr A diabetic medications on hold for the time being, for the home team to review in the morning
#TIP 1 There is normally a ‘hypoglycemia toolkit’ on the ward, containing sugary food
#TIP 2 Make sure you document well. Be sure to write down the BGL level initially, intervention performed and BGL afterwards
If patient is drowsy/not alert:
Call a MET call! You need HELP. This can be a potentially life threatening situation.
Utilize the ABCDE approach.
In the meantime, see if you can get IV access, whilst waiting for the MET team.
If you have IV Access Give: IV 50ml of 50% Dextrose
If you can’t get IV access Give IM Glucagon 1 mg
4. Once the patient is more alert, revert to the alert patient management described above.
ResourcesAustralian Medicines Handbook. RACGP. Pharmaceutical Soceity of Australia. 2021. https://amhonline.amh.net.au/Association of Anaesthetists of Great Britain and Ireland. Peri-operative management of the surgical patient with diabetes 2015. Anaesthesia 2015; 70: 1427-1440.Blood glucose monitoring. Diabetes Australia. https://www.diabetesaustralia.com.au/living-with-diabetes/managing-your-diabetes/blood-glucose-monitoring/ 2021Guideline for Perioperative Care for People with Diabetes Mellitus Undergoing Elective and Emergency Surgery. 2021 Centre for Perioperative Care. Academy of Medical Royal Colleges. March 2021INPATIENT MANAGEMENT OF DIABETES. NSW hospital Endocrinology guideline. https://www.wslhd.health.nsw.gov.au/ArticleDocuments/2170/MO%20Handbook%20-%20Inpatient%20Management%20of%20Diabetes.pdf.aspx 2020 Phillips PJ. HbA1c and monitoring glycaemia. Aust Fam Physician. 2012 Jan-Feb;41(1-2):37-40. PMID: 22276282. Mayer-Davis EJ, Kahkoska AR, Jefferies C, et al. ISPAD Clinical Practice Consensus Guidelines 2018: Definition, epidemiology, and classification of diabetes in children and adolescents. Pediatr Diabetes 2018; 19 Suppl 27:7.Severe Euglycaemic Ketoacidosis with SGLT2 Inhibitor Use in the Perioperative Period. AUSTRALIAN DIABETES SOCIETY. https://diabetessociety.com.au/documents/2018_ALERT- ADS_SGLT2i_PerioperativeKetoacidosis_v3__final2018_02_14.pdf 2018Vincent Wong, Glynis Ross, Jennifer Wong and David Chipps PERI ‐OPERATIVE DIABETES MANAGEMENT GUIDELINES AUSTRALIAN DIABETES SOCIETY July 2012