Management of Diabetes for People Receiving Enteral Feeding in Hospital

Introduction

When patients with diabetes mellitus are being artificially fed via the enteral route (e.g. nasogastric, gastrostomy or jejunostomy) glycaemic control can prove difficult. This may complicate their medical condition and delay recovery. To maintain optimal glycaemic control while ill and receiving enteral nutrition, patients may require alteration of their usual diabetes treatment. It is imperative that there is good communication between the Diabetes Team, the Nutrition Support Dietitian, and the extended medical teams.

This guideline is aimed at patients who:

• Are currently on 24 hour feeding and IV insulin being transferred to SC insulin.
• Have pre-existing diabetes and require enteral feeding
• Develop hyperglycaemia while being enterally fed.

Target glycaemic control

For patients being enterally fed, the extremes of glycaemic control should be avoided. A target blood glucose reading should be between 6–12mmol/L. These targets should be adjusted according to individual patient requirements.

Diabetes therapy

The majority of patients with diabetes will experience a rise in their blood glucose levels when they commence enteral nutrition. There are often other factors such as infection and recent surgery that will affect glycaemic control. The following principles should be adhered to:

• Oral hypoglycaemic agents may not provide adequate glycaemic control. In this instance the patient should usually be converted to insulin and the oral hypoglycaemic agent should be discontinued.
• The usual therapy of choice is insulin, initially via an IV sliding scale, see Table 1 below.
• Frequently re-evaluate the sliding scale regimens as the insulin dose may need to be adjusted to achieve target glycaemic control.
• Once the patient’s blood glucose is stabilised and feeding has been established, he / she should be converted to SC insulin injections.
• Discontinue the IV infusion once the initial SC injection has been administered.
• SC insulin dose can be calculated as follows:
  1. Take an average of the patients 24 hour insulin requirements on the intravenous sliding scale.
  2. Subtract 25% from this value and this will be their total daily insulin dose.
  3. This will usually be split into 2 or more injections (see section on feeding regimens).
• Retrospective treatment with corrective doses of SC insulin should be avoided, instead the insulin doses should be increased prospectively i.e. avoid boluses of short-acting insulin.

Table 1 – Insulin IV sliding scale regimen

Add 50units of soluble insulin (Actrapid^® or Humulin S^®) to 50ml of 0.9% sodium chloride in a 50ml syringe. Infuse IV using a pump and adjust according to sliding scale:

Notes:

• Check capillary blood glucose hourly initially then 2 hourly
• If blood glucose regularly outwith range of 6–12 mmol/L, insulin doses should be reassessed.

Maintaining glycaemic control

• If the feed stops unexpectedly, blood glucose levels should be closely monitored, as patients are at risk of hypoglycaemia. If necessary, an IV glucose infusion should be commenced until feeding can be resumed.
• If feed is stopped electively the patient may require to recommence IV insulin and glucose, depending on length of fast.

Enteral feeding regimens

For inpatients with diabetes, the enteral feeding regimen will be recommended by the dietitian to meet the individual’s nutritional requirements. To maximise glycaemic control, we suggest using the following feeding regimens:

Intermittent feeding –

1. May be commenced at varying times and be of variable duration (minimum 12 hours, maximum 20 hours).
2. Calculate total daily insulin SC dose – average 24 hour IV requirements minus 25%.
3. Administer 2/3 of the dose as pre-mixed 30/70 insulin SC (Humulin M3^®) at the start of the feed. Discontinue IV insulin after the first SC dose has been administered.
4. Administer the remaining 1/3 of the insulin SC dose as isophane (either Insulatard^® or Humulin I^®) at 12 hours.

Bolus feeding –

1. The feed is divided into at least 4 boluses, ensuring the carbohydrate intake is evenly distributed throughout the day, to mimic breakfast, lunch, dinner, supper and between meal snacks.
2. Calculate total daily insulin SC dose as above. (i.e. average 24 hour IV requirements minus 25%).
3. Administer 2/3 of the dose as pre-mixed 30/70 insulin SC (Humulin M3^®) before the breakfast bolus feed. Discontinue IV insulin after the first subcutaneous dose has been administered.
4. Administer the remaining 1/3 of the dose as pre-mixed 30/70 insulin SC (Humulin M3^®) around 9–10 hours later but before the dinner bolus feed.

Glycaemic control should be closely monitored and insulin doses should be adjusted accordingly, if advice on insulin adjustment is required, contact the Diabetes Team.

Key points

• Hypoglycaemia is a medical emergency and should be treated urgently. If the patient is on IV insulin, stop the pump immediately. To treat hypoglycaemia give:20g quick-acting carbohydrate via enteral tube: e.g. 50–70ml of Ensure Plus® Juce or 100mls of original Lucozade®, then flush.
  • Check blood glucose after 10–15 minutes. Repeat treatment up to three times until glucose >4mmol/L. Refer to full Hypoglycaemia guideline
  • You must always follow up with another feed bolus or by recommencing the feed to prevent the blood glucose falling again. If the tube has been dislodged or the patient is unconscious you will need to gain IV access and administer bolus IV glucose (see Hypoglycaemia guideline under 'severe hypoglycaemia').
• For patients receiving enteral nutrition, extremes of glycaemia should be avoided and target blood glucose levels should be between 6–12 mmol/L. All patients with type 1 diabetes must have their urine checked for ketones daily.
• Patients with diabetes who are commenced on enteral feed will usually require an increase in their diabetes medication or conversion to insulin.
• If a patient on enteral nutrition becomes hyperglycaemic, then the diabetes therapy needs adjusting, rather than a reduction in nutrition. This usually requires an increase in the insulin dose.
• Communication between the Diabetes Team and all of the healthcare professionals looking after the patient is vital, and the targets for blood glucose control should be established for the individual patient, avoiding hypoglycaemia.
• As the patient’s clinical condition improves and activity level increases, insulin requirements may reduce significantly. If the patient comes off enteral feeding and returns to normal eating, they should usually return to their pre-illness diabetes regimen.