Abc do diabetes

Abc do diabetes

(Parte 10 de 19)

Further dietary advice

Sulphonylurea Poor control

Indications for insulin in Type 2 diabetes mellitus

ABC of Diabetes given a three-month trial of insulin and then make their decision, which experience shows to be usually affirmative. Those with a short life expectancy do not necessarily benefit, and those with other medical disorders will require individual consideration.

•Insulin is often required in patients with intercurrent illness.

Many disorders, notably infections, increase insulin resistance, leading to the temporary need for insulin. Withdrawal of insulin after recovering from the illness is important provided adequate control is achieved and maintained.

Corticosteroids always exacerbate hyperglycaemia and often precipitate the need for insulin. This should not deter doctors from prescribing them when they are needed.

Combination treatment with insulin and metformin Metformin can be given together with insulin to overweight Type 2 diabetic patients: this can to a small extent limit the inevitable weight gain following introduction of insulin. A combination of sulphonylureas with insulin gives little benefit and has the added disadvantage that patients must continue with both modes of treatment.

Insulin regimens suitable for Type 2 diabetic patients are described in chapter 5.

The figure showing the cross sectional and 10-year cohort data for HbA1c in patients receiving intensive or conventional treatment is adapted from

UKPDS Lancet1998;352:837-53 with permission from Elsevier Science. The histogram showing increased patient compliance is adapted from Paes AH, Bakker AS, Soe Agnie CJ. Impact of dosage frequency upon patient compliance. Diabetes Care 1997;20:1512-17.

I was like a dried tree, but you have given me new life. An Ethiopian villager, after starting insulin.

The astonishing power of insulin to restore health and wellbeing to rapidly deteriorating newly diagnosed Type 1 diabetic patients is as remarkable now as it was in 1922. After Banting gave insulin to Elizabeth Hughes in that year, she wrote to her mother that “it is simply too wonderful for words this stuff.” Insulin to this day always has this effect; the challenge now is to optimise control in order to maintain health throughout life.

Insulin is also needed to enhance well-being and control in many Type 2 diabetic patients when the natural progression of their disease has lead to loss of optimal control. The potential to reduce the development of long-term diabetic complications as demonstrated by the UKPDS (see page 42) has led to a recent explosion in conversions from tablets to insulin. The difficult decisions which surround the need for insulin in this situation, together with benefits, uses and misuses of insulin have been described in the previous chapter.

The use of insulin must be tailored to meet individual requirements. The aim is to achieve the best possible control in the circumstances, avoiding at all costs the disabling hypoglycaemia which can occur if control is excessively tight. In some elderly patients and those who lack motivation, it is therefore wise to aim only at alleviating symptoms and not to attempt very strict control.

Types of insulin

Soluble insulins These were first introduced in 1922. They have a rapid onset of action (within 15-30 minutes) and a relatively short overall duration of action of six to eight hours. They play an important part in both daily maintenance of diabetic patients by subcutaneous injection, and also in managing emergencies, when they can be given intravenously or intramuscularly. Other insulin preparations are not suitable for intravenous or intramuscular use.

New recombinant insulin analogues These have a very rapid onset and very short action, and have been developed by altering the structure and thus the property of the insulin. The preparations available in the United Kingdom

5Insulin treatment An Ethiopian patient carrying his diabetes equipment to the clinic

Elizabeth Evans Hughes (1907-1981). Banting’s prize patient, who found insulin “unspeakably wonderful.” The photograph is from Banting’s scrapbook

Insulins available in the United Kingdom

Insulins are available as human, pork or beef preparations, or as insulin analogues.

Very short acting insulin analogues •Insulin Aspart •Insulin Lispro (Novo Rapid) (Humalog)

Short acting neutral soluble insulins •Human Actrapid•Pork Actrapid•Beef Neutral

•Human Velosulin•Pork Neutral

•Insuman Rapid

Medium acting isophane insulins •Human Insulatard•Pork Insulatard•Beef Isophane

•Humulin I•Pork Isophane

•Insuman Basal

Medium acting insulin zinc suspensions •Human Monotard•Lentard MC•Beef Lente

•Humulin Lente(beef or pork)

Long acting insulin zinc suspensions •Human Ultratard

•Humulin Zinc

Long acting insulin analogue •Insulin Glargine at present are Insulin Lispro (Humalog) and Insulin Aspart (Novo Rapid). They have some advantages because they may be given immediately before meals (or even immediately after meals if necessary). By virtue of their very short action, there is less hypoglycaemia before the next meal, and when they are used before the main evening meal nocturnal hypoglycaemia is effectively reduced.

There is a risk of postprandial hypoglycaemia if they are used before a meal with a very high fat content because of the delayed gastric emptying. Duration of action is short and does not normally exceed three hours, and their use is therefore inappropriate if the gap between meals exceeds about four hours. Preprandial blood glucose levels are slightly higher than with conventional soluble insulins.

They are also ideal for use in continuous subcutaneous insulin infusion pumps (CSII).

Protamine insulins These are medium duration insulins introduced in Denmark during the 1930s. Isophane insulin is the most frequently used insulin in this group.

Insulin zinc suspensions These were first introduced during the 1950s; there are several preparations with widely ranging durations of action. There are limited indications for using insulins with a very long duration of action (ultratard).

Insulin glargine This is a new prolonged action, soluble insulin analogue (clear solution) forming a microprecipitate after subcutaneous injection. Its onset of action is after about 90 minutes, it has a prolonged plateau rather than a peak, and lasts 24 hours or more. Thus it mimics more closely the basal insulin secretion of healthy people. When taken at bedtime it reduces the incidence of nocturnal hypoglycaemia, and also reduces the prebreakfast hyperglycaemia. It does not appear to reduce symptomatic or severe hypoglycaemia during the day, and there is no significant beneficial effect on overall diabetic control. More extensive clinical experience in using this insulin is still needed.

Insulin mixtures Some preparations of insulin are presented as proprietary mixtures in either vials or pen cartridges, eliminating the need for patients to mix insulins in the syringe. The most popular mixture contains 30% soluble insulin and 70% isophane, whereas the whole range also includes ratios 10%/90%, 20%/80%, 40%/60%, and 50%/50%. These insulin mixtures represent a considerable advantage for many patients, especially those who find it difficult to mix insulins in the syringe or those whose visual acuity is impaired. Details of the types of insulin available in the United Kingdom are shown in the box.

Selection of insulin

The choice of insulin preparation is based on the duration of action. Although insulins can be broadly classified as having very short, short, medium or long duration of action, their effect varies considerably from one patient to another and can be discovered in the individual patient only by trial and error. There are several preparations of medium acting insulins, but those most often used are either one of the isophane preparations or less frequently Human Monotard zinc insulin preparation (see box on page 19).

Most patients (85%) now use insulin of human sequence, a few prefer porcine preparations, while use of some insulin

ABC of Diabetes

Some insulins

Insulin mixtures

These are all mixtures of a short acting soluble insulin (or very short acting insulin analogue) with a medium acting isophane insulin (or insulin analogue). The number after the insulin name indicates the percentage of the short acting insulin, for example, “30” or “M3” indicates 30% soluble insulin mixed with 70% isophane insulin.

•Human Mixtard 10 (pen only) •Human Mixtard 20 (pen only)

•Humulin M2 (pen only)

•Human Mixtard 30•Pork Mixtard 30

(Parte 10 de 19)