Managing Diabetic Patients in Surgical Wards

The diagnosis of diabetes
Medications
Elective surgery
Emergency surgery
Diabetic emergencies
Referral to internal medicine and/or endocrinology
Glucose-insulin sliding scale

Approximately one third of patients in our surgical wards are diabetic. A complication of diabetes may be the reason for admission (e.g. diabetic foot infection) or diabetes may need to be managed as a comorbid illness for an unrelated surgical condition.

In almost all surgical conditions diabetic patients face a higher perioperative morbidity and mortality, as well as increased length of hospital stay.

An admission to a surgical ward represents an opportunity for assessing and managing this condition correctly. This guideline is aimed at the perioperative management of type-2 diabetics.

The primary goal is to maintain glucose control- (this has been shown to improve surgical outcome) by avoiding random glucose levels above 10.0mmol/l and preventing hypoglycaemic episodes.

This is usually done by continuing the patients’ routine hypoglycaemic medications, and monitoring blood glucose 6 hourly. Additional glucose control can be achieved by using an insulin/glucose sliding scale. A diabetic diet should be prescribed on admission to the ward.

Complexity arises in patients who are unable to eat a normal diet, who have systemic sepsis and/ or renal or liver impairment.

The diagnosis of diabetes

In patients presenting with hyperglycaemia (Blood Glucose > 7.8mmol/L) it is important to distinguish between stress related hyperglycaemia and diabetes mellitus.

The HbA1c is a useful tool as it provides information on pre-admission glycaemic control and helps plan an optimised in-patient and discharge treatment plan for the diabetic patient.

A known diabetic patient with an HbA1c > 7.5% is poorly controlled, either due to inadequate medication and/or poor compliance. This finding must stimulate an interrogation of these factors, and a referral to the primary treating physician with a clear goal to improve this.

When to measure HbA1c

1. Patients with hyperglycaemia
2. All known diabetics admitted, who have not had it checked in last 3-months

In Hospital glucose Targets

1. Pre-meal glucose targets <7.8 mmol/L
2. Random BG <10.0 mmol/L
3. To avoid hypoglycemia, reassess insulin regimen if BG levels fall below 5.5 mmol/L

Medications

1. Insulin
   • Indications
   • Hyperglycaemia despite lifestyle modification and oral therapy, HbA1c >7.5%
   • Major stress – surgery or medical illness
   • Pregnancy
   • Severe renal/hepatic impairment
   • Protophane 0.3 U/kg/day = total daily dose, given at night (intermediate to long-acting insulin)
2. Oral anti-hyperglycaemics
   • Metformin (Biguanides)
     • Increase dose according to HbA1c – Max 850mg 8hourly
     • Avoid in renal impairment GFR < 50ml/min
     • Continue use even if insulin introduced into chronic treatment (especially if BMI > 25)
     • Able to lower HbA1c by 1% at maximum dose
   • Glimeperide (Sulphonylureas)
     • Increased to a maximum dose of 4mg daily
     • Avoid in renal impairment and elderly
     • Risk of hypoglycaemia
     • Stop if insulin introduced into chronic treatment
     • Able to lower HbA1c by 0.5% at maximum dose

Elective surgery

All diabetic patients undergoing elective surgery should have a recent HbA1c level checked (not older than 3-months).

If it is greater than 9% (indicative of poor chronic glucose control) consider delaying surgery (if pathology allows) and refer back to primary level care for optimisation.

Diabetic patients should be operated first on the slate, if possible.

1. Minor Surgery
   • Minimal intervention, as often day case or short stay
   • Omit morning oral meds on day of procedure
   • Continue basal insulin if part of patient treatment
2. Major Surgery
   • Stop oral therapy
   • Continue basal insulin if part of patient treatment
   • May be longer delay in recommencing oral medication
   • Adjust insulin as in emergency setting, per sliding scale
   • Ensure adequate renal function prior to recommencing oral meds

Emergency surgery

1. Pre-op/NPO
   • On oral anti-hyperglycaemics
     • Stop oral therapy
     • Sliding scale with 6 hourly glucose checks
     • If HbA1c > 7% start basal insulin 0.3 U/kg/day (protophane nocte)
   • On Insulin +/- oral anti-hyperglycaemics
     • Stop oral therapy
     • Continue normal basal insulin or if not sure of dose 0.3 U/kg/day
     • Sliding scale with 6 hourly glucose checks
2. Post-op/Discharge
   • On oral anti-hyperglycaemics
     • Restart oral meds when tolerating oral intake
   • On Insulin +/- oral anti-hyperglycaemics
     • Restart oral meds when tolerating oral intake
     • Adjust basal insulin by 2 U every 2 days to achieve appropriate control
     • Communicate change in insulin dosages to primary care facility in discharge summary

Diabetic emergencies

1. Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS – serum osmolality >320 mOsm/L)
   • Ideally managed in a high care setting (associated 5-10% mortality)
   • 2 hourly blood glucose, 6 hourly blood gases
   • Find and manage precipitating cause (infection/MI/ other)
   • Components
     • IV insulin infusion (50u Actrapid in 200ml Normal Saline)
     • Glucose > 10mmol/L = 24ml/hr (6u/hr)
     • Glucose 4 – 10mmol/L = 12ml/hr (3u/hr)
     • Glucose < 4mmol/L = 50ml of 50% dextrose and stop infusion for 2 hours
     • Aim is resolution of ketoacidosis – pH > 7.3, serum ketones negative, reduction in glucose 3mmol/L per hr
     • Covert to subcut insulin sliding scale
   • IV fluids (deficit 6-12L)
     • 1L N/S stat
     • 1L N/S over 1hr (1000ml/hr)
     • 1L N/S over 2hrs (500ml/hr)
     • 1L N/S over 4hrs      (250ml/hr)
     • Then if glucose > 15mmol/L = 1L normal saline 6hrly (166ml/hr)
     • Then if glucose < 15mmol/L – 1L rehydration solution (1/2 normal saline + 5% dextrose) 6hrly (166ml/hr)
   • Elecytrolytes
     • Potassium supplementation (passing urine)
       • <3.5mmol/L – add 40mmol/L KCL to N/S
       • >3.5 – 5.0 mmol/L – add 20mmol/L KCL
       • > 5.0mmol/L – nil
2. Hypoglycaemia
   • Glucose < 3.9mmol/L
   • If alert and awake, to take oral glucose
   • Drowsy = IV 50ml 50% dextrose stat, no IV access glucagon 1mg IMI
   • 10 % dextrose fluid 8 hourly
   • Find and correct cause

Referral to internal medicine and / or endocrinology

The following patients should be referred to internal medicine:

Inpatient referral:

• inability to obtain glucose target despite adherence to above guidelines

Outpatient follow up:

• all diabetic patients must be followed up by their treating physician, or referred to the Day Hospital if newly diagnosed.
• If the hypoglycaemic medications have been changed or found to be inadequate during the hospital admission,  a clear discharge summary must be made available
• The following patients will benefit by a MOPD/ diabetic clinic follow up:
• Newly diagnosed diabetics
• Patients newly initiated on insulin
• Young diabetics (<35 years)
• Diabetics with renal impairment or proteinuria
• Diabetics with poorly controlled hypertension
• Patients with extensive well established target organ disease (i.e. multiple amputations) can be managed at CHC level.

Glucose-Insulin sliding scale