Insulin is the mainstay of treatment of type 1 diabetes (also known as insulin-dependent diabetes mellitus). Because it is inactivated by gastrointestinal enzymes, it is administered by injection, usually subcutaneous. Insulins fall into one of three categories: short-acting (soluble, lispro, aspart, glulisine), intermediate (isophane, zinc suspension, detemir), and long-acting (zinc suspension, glargine).

However, the duration of action differs so regimens must be individually tailored for each patient, many of whom will be on mixed insulins containing more than one type (eg. Mixtard, Humalog mix, Humulin M3). Patients with diabetes are at increased risk of developing renal or cardiac disease or stroke, so may be on a variety of other medication, including antihypertensives, statins or aspirin.

Dosage regimen

* Short-acting insulins need to be injected shortly before or after meals, as they have a fast onset of action.

* Intermediate insulins are usually injected twice a day, though detemir may only be used once daily.

* Long-acting insulins are usually injected once a day.

* Mixed insulins tend to be injected twice daily.

Patient's knowledge of the medicine's use

* Does the patient understand the need for, and actions of, their medications?

* If the patient is using more than one insulin, is he/she aware of the actions of each?

* If the patient is taking an oral antidiabetic in addition to insulin, is he/she aware of the reason for the combination?

* Is the patient aware why they are taking any other prescribed medications (eg statins, aspirin, antihypertensive agents)?

Is the medicine working?

* Does the patient know their most recent HbA1c measurement? If the patient has good diabetic control the result should be below 7%.

* Does the patient self-monitor blood glucose levels? They should be between 4 and 9 mmol/L. Unsatisfactory results warrant referral.

Side effects

* Does the patient experience hypoglycaemia? This is a common side effect of insulin therapy. Patients should be aware of the symptoms and how to deal with them, and be advised to report incidents to their prescriber so their insulin dose or preparation can be reviewed.

Monitoring

* When did the patient last have their HbA1c checked? The BNF recommends at least every 3-6 months.

* When did the patient last have a diabetes review? Most surgeries carry out a full regular diabetes check including weight, diet, lipid level, examination of feet and patient education. Find out your local practice's protocol so you can refer patients if necessary.

Lifestyle

Lifestyle advice should be offered to patients including weight loss, exercise (if approved by GP), healthy diet (including reduced consumption of fats and sugars) and smoking cessation. If you provide a quit service offer the chance to participate or refer to other providers and record on MUR form.

Martin Wilson, pharmacist at The Co-operative Pharmacy, Leckie Rd, Walsall/AF

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