Insulin

Insulin - plays a key role in the regulation of carbohydrate, fat and protein metabolism. Hyperglycaemia and insulin resistance are common in critically ill patients, even if they have not previously had diabetes.Two studies (Van den Berghe G, et al. N Engl J Med 2001; 345: 1349–67 and Van den Berghe G, et al. N Engl J Med 2006; 354: 449–61) have shown that tight control of blood glucose levels (between 4.4 and 6.1 mmol/l) reduces mortality among longer stay ( > 3 days) adult intensive care patients. The incidence of complications such as septicaemia, acute renal failure and critical illness polyneuropathy may also be reduced. In practice, however, many centres have found this tight control problematic, with increased risks of hypoglycaemic events. Indeed the NICESUGAR study (N Engl J Med 2009; 360: 1283–97) reported a higher mortality with tight glucose control.

Uses
• Hyperglycaemia
• Tight glucose control
• Emergency treatment of hyperkalaemia

Administration
• Hyperglycaemia
Soluble insulin (e.g.Actrapid) 50 units made up to 50 ml with sodium chloride 0.9%
Adjust rate according to the sliding scale below

Insulin sliding scale:

Blood sugar (mmol/l)	Rate (ml/h)
<3.5	0
3.6–5.5	1
5.6–7.0	2
7.1–9.0	3
9.1–11.0	4
11.1–17.0	5
>17.0	6

The energy and carbohydrate intake must be adequate; this may be in the form of enteral or parenteral feeding, or IV infusion of glucose 10% containing 10–40 mmol/l KCl running at a constant rate appropriate to the patient’s fluid requirements (85–125 ml/h). The blood glucose concentration should be maintained between 4 and 10 mmol/l.

Monitor:
Blood glucose 2 hourly until stable then 4 hourly
Serum potassium 12 hourly

How not to use insulin
SC administration not recommended for fine control
Adsorption of insulin occurs with PVC bags (use polypropylene syringes)
If an insulin infusion in running with feed and that feed is interrupted, e.g. for the patient to go for a scan, then the insulin rate should be reduced and re-titrated.This is a common cause of hypoglycaemia

Adverse effects
Hypoglycaemia

Cautions
Insulin resistance may occur in patients with high levels of IgG antibodies to insulin, obesity, acanthosis nigricans and insulin receptor defects. Co-administration of corticosteroids and inotropes may adversely affect glycaemic control