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Choosing the right insulin and insulin regimes

With so many insulin products on the market, specialist nurse Jennefer Richmond offers up-to-the-minute advice

The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated that tight glycaemic control leading to a reduction in HbA1c levels is associated with a reduced risk of the long-term complications of diabetes. These trials, plus the rapid increase in the numbers of people with diabetes and the recent publication of the national service framework for diabetes, have provided the impetus for 'treating to target'.

Therefore, those patients with type 2 diabetes who are not achieving HbA1c target levels with oral therapy are now being transferred to insulin much more readily than in previous years.

But there are so many insulin products currently on the market that choosing one most suited to each individual can be an extremely daunting task.

Insulin analogues and the newer preloaded insulin pens have made the complexity of starting insulin a little easier, particularly for older patients with type 2 diabetes

who are not controlled with oral therapy alone.

In the past most people who required insulin needed to take it at least twice daily. Any less than this was unlikely to achieve adequate metabolic control. But with the advent of insulin glargine and its reported reduction in hypoglycaemic episodes in research studies, once-daily insulin may be the preferred option.

Once-daily glargine may be used as a baseline insulin in a qds regime with either type 1 or type 2 diabetes patients or it may be used in conjunction with an oral agent in type 2 patients. Insulin glargine provides a 'peakless' profile over 24 hours similar to that seen with continuous subcutaneous insulin infusion (CSII)1,2.

It is available in 10ml vials, 3ml cartridges and preloaded pens. Unfortunately, patients have found both the Optiset pen and the Optipen confusing and difficult to use, but the new Autopen 24 is now available to use with glargine 3ml cartridges.

For this particular regime, an oral agent is normally taken with breakfast and the glargine may be taken any time provided it is always at the same time3. The dose is then titrated up over a period of weeks according to the fasting blood glucose readings.

Research has shown patients receiving glargine have fewer hypoglycaemic episodes, particularly at night1,4 than with isophane insulins. This may also be the regime of choice for those who require help with administration.

Glargine can be also be used as a baseline insulin for people with type 1 diabetes, using either a short-acting or rapid-acting insulin analogue before each meal. The advantage of the rapid-acting analogues ­ Novorapid and Humalog ­ is that patients do not have to wait the statutory 20-30 minutes before eating, making it much more convenient for patients.

Indeed from experience, the majority of people questioned in clinic do not wait the required length of time anyway. This may cause post-prandial peaks in blood glucose levels when using the short-acting insulins as opposed to rapid-acting analogues. The rapid-acting analogues start working immediately, peak for two hours and last for four to five hours.

Novorapid and Humalog are available in 3ml cartridges and also preloaded pens (see table on page 57).

For people with type 2 diabetes who require large doses of insulin, around 80-90 units bd, it may be better to transfer them to a qds regime so that the dosage of insulin is reduced for each injection. Many type 2 patients are overweight and take metformin tablets and it is recommended that these people continue with metformin when starting insulin unless there are contraindications to its use.

For those people who start bd regimes, again the analogue mixtures are less complicated and the preloaded pens are easy to use, although at the moment the range of analogue mixtures is fairly limited ­ see second table on page 57.

Most patients when starting insulin want a quick and easy insulin delivery system, particularly if they are elderly.

Starting insulin is a difficult time emotionally for many people and this together with the volumes of information they are required to read can make insulin therapy overwhelming.

Giving patients an easy-

delivery system goes part way to relieving some of the associated stress.

Advantages of insulin analogues

 · Fewer reported hypoglycaemic episodes with both rapid-

acting and long-acting

analogues

 · More convenient for patients ­ no waiting to eat

 · No resuspension of the insulins as they are all clear, including glargine

 · Easy-to-use preloaded pens (rapid-acting analogues)

Finally, continuous subcutaneous insulin infusion therapy is gaining popularity in this country. Short-acting insulin is delivered subcutaneously via a small cannula inserted under the skin and attached to an insulin pump about the size of a pager. The cannula is changed every few days by the patient.

The basal dosage regime is worked out on an individual basis and the patient gives him or herself a bolus with each meal taken. The drawback with this system is the expense.

But for people who have been struggling to achieve good metabolic control and have tried all other alternatives, an insulin pump may provide the long-awaited solution.

Available pen devices for insulin analogues

Company Pen types Insulin (analogues)

Novonordisk Novopen, Innovo, Novorapid

Flexpen (preloaded)

Eli-Lilly Humapen Ergo prefilled Humalog (lispro)

Aventis Optipen, Optiset, Lantus (glargine)

Autopen 24

Easy-to-use pens for analogue mixtures

Company Insulin analogue mixtures Preloaded pens

Novonordisk Novomix 30 Flexpen

Eli-Lilly Humalog Mix 25, Humalog mix

Humalog Mix 50 prefilled pens

References

1 Yki-Jarvinen H et al. Less nocturnal hypoglycaemia and better post-dinner glucose control with bedtime insulin glargine compared with bedtime NPH insulin during combination therapy in type 2 diabetes. HOE901/2002. Diabetes Care 2000;23:1130-6

2 Rosenstock J et al. Basal insulin therapy in type 2 diabetes: 28-week comparison of insulin glargine (HOE901) and NPH insulin. Diabetes Care 2001;4:631-36

3 Barnett AH et al. Treating to target in type 2 diabetes: from lifestyle change to insulin therapy, a consensus guide. Modern Diabetes Management 2003;4:2-5

4 Ratner RE et al. Less hypoglycaemia with insulin glargine in intensive insulin therapy for type1 diabetes. US study group of insulin glargine in type 1 diabetes. Diabetes Care 2000;223:639-43

Further reading

Department of Health. National service framework for diabetes: delivery strategy (available at www.doh.gov.uk/nsf/diabetes)

DCCT Trial Research Group. The effect of intensive diabetes therapy on the development

and progression of long-term complications in insulin-dependent diabetes mellitus.

New Engl J Med 1993;329:977-86

Stratton IM et al. Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study. BMJ 2000;321:405-12

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