Complications of insulin therapy

At the injection site:

Shallow injections result in:

• Intradermal insulin delivery
• Painful, reddened lesions
• Scarring
• (Rarely) abscesses

Local allergic responses sometimes occur spontaneously

There are 2 forms of lipodystrophy that can occur:

• Lipoatrophy (a local allergic response now almost completely abolished by the use of highly purified insulins)
• Lipohypertrophy (as a result of overuse of a single injection site)

Insulin resistance:

• The most common cause is obesity
• Are often associated behavioural problems

Weight gain:

Patients who are non-compliant with their diet and predisposed to weight gain may show progressive weight gain on treatment. Insulin makes you feel hungry!

Hypoglycaemia:

• Most common complication of insulin therapy
• Symptoms develop when blood [glucose] < 3mmol/L
• Symptoms typically develop over a few mins

Common signs/symptoms:

• Sweating
• Tremor
• Palpitations
• Pallor

Many patients with long-standing diabetes report ‘hyperglycaemia unawareness’. These patients are at a greater risk of a more severe hypoglycaemia, with signs including:

• Drowsiness
• Clumsiness
• Inappropriate behaviour
• Aggression

Just beyond these symptoms, patients enter a hypoglycaemic coma, often with convulsions

1 in 3 diabetics will enter a hypoglycaemic coma during their lifetime.

Patients are most at risk of hypoglycaemia just before meals and at night. Irregular eating habits, unusual exertion or excessive alcohol may precipitate episodes.

Nocturnal hypoglycaemia:

Basal insulin requirements fall during the night, but increase from about 4am onwards, at a time when levels of injected insulin are falling. As a result, many patients awake with a high glucose level but find that increasing the dose of insulin at night increases the risk of hypoglycaemia in the early hours.

Can be minimised in 3 ways:

• Checking that a bedtime snack is taken regularly
• Taking intermediate insulin before bedtime (rather than at supper)
• Reducing the dose of soluble insulin before supper, since the effects of this persist well into the night