Module 203.2 en_0

Editor's Notes

1. This module will cover the basics of insulin use. While it is recognised that in most countries only doctors may prescribe and change doses of insulin, it is important that other health professionals have a good understanding of how insulin works, when and why it is needed, and the rationale for dose changes. It is not expected that having completed this module, participants will be able to adjust insulin; but rather that they will know when a change is needed and be able to counsel people on self-management.
2. Insulin is a hormone secreted by the beta cells in the islets of Langerhans. As the blood circulates through the pancreas, the beta cells “read” the level of glucose and secrete the appropriate amount of insulin. In people without diabetes the normal physiological insulin response is characterised by a low level of background (basal) insulin, rising slightly overnight to suppress hepatic glucose output, with surges of insulin (bolus) triggered by the rise of glucose or other nutrients following eating. These surges are proportional to the size and composition of what is eaten. Typically, the surge of insulin peaks at 20 to 30 minutes after food intake with circulating insulin returning to basal levels within 2 hours.
3. Insulin is essential for life and has many different actions: At the cell level, insulin binds to the receptors of the cell surface. This causes a reaction which allows glucose to enter the cell Insulin also lowers glucose by suppressing glucose output from the liver. This requires only a small amount of insulin, such as the amount of basal insulin. When more insulin is available, glucose uptake in the periphery (adipose tissue and muscle) is stimulated. Insulin regulates the conversion of glucose into triglycerides and the breakdown of triglycerides into fatty acids in the fat cells. Adequate amounts of insulin result in glucose being stored as triglycerides in the fat cells. When insulin levels fall, triglycerides breakdown. Insulin inhibits the enzyme lipase, which breaks down stored fat into fatty acids and glycerol When blood glucose levels are normal, insulin assists muscle cell enzymes to maintain muscle mass by promoting the uptake of amino acids and preventing the breakdown of protein
4. People with type 1 diabetes require insulin for survival – they cannot be managed on oral agents. There is some limited evidence suggesting that the use of metformin within the first trimester of pregnancy is safe. However, there is no evidence for other glucose-lowering agents. Therefore the use of agents other than insulin is not recommended during pregnancy. Ideally, women with type 2 diabetes on glucose-lowering medicines should be transferred to insulin therapy prior to conception. Glucose-lowering medicines should not be recommenced until after the birth and the woman is no longer breast feeding. People with type 2 diabetes may require short-term insulin therapy during periods where their blood glucose levels remain high – such as around a surgical event or illness. Insulin is often needed in type 2 diabetes depending on the stage of progression the disease is at and the degree of beta cell loss. The UKPDS showed that approximately 50% of people with type 2 diabetes require insulin therapy to supplement or replace glucose-lowering medicines within 5 to 10 years of diagnosis. This is known as secondary failure.
5. In people with diabetes, insulin therapy is used to try to replicate the normal physiological insulin response. There are many different types of insulin and insulin regimens. A chosen regimen should be tailored to the needs of the person with diabetes taking into consideration the following: Type of diabetes How often the person is willing to inject Their normal eating and exercise pattern Ability to self-monitor blood glucose Frequency of monitoring Usual pattern of blood glucose levels Age Dexterity, ability to draw up insulin into a syringe Individualized glycaemic target Cost
6. As mentioned previously, there are various insulins available. As shown here, their actions differ in terms of their onset, peak and duration. Due to their short duration, rapid- or short-acting insulins are usually used to replicate the surge or bolus of insulin seen in a person without diabetes following ingestion of food. Due to their longer duration, intermediate- or long-acting insulins are used to provide background or basal insulin coverage. It is important to note that the action times shown in this table are approximate and will differ between individuals. They will also differ within individuals on different days. Premix insulins are also available, they are a combination of either Rapid or Short acting insulin with an intermediate acting insulin. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. (2008). Canadian Diabetes Association 2008 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. Canadian Journal of Diabetes, 32(suppl 1).
7. This slide shows the output of 3-day continuous blood glucose monitoring in a person with type 1 diabetes. Despite taking the same dose of insulin, eating the same diet and performing the same amount of exercise, the absorption of the insulin, and therefore the blood glucose levels, are highly variable . HBGM misses most of the highs and lows; these could affect A1c, especially if there are a lot of hypoglycaemic events.
8. These are some of the factors that affect the absorption and therefore the time action of insulin. For example, in the presence of lipohypertrophy  an abnormal build up of fat under the skin in areas of repeated injection. Larger volumes of injected insulin are known to affect insulin absorption by prolonging or delaying the insulin’s peak effect (sometimes, if a person is on a dose of more than 50 units, and blood glucose levels are not at target, it can be beneficial to split the dose into two injections). Insulin may be absorbed at faster or slower rates from some sites than others, although this may not be as true for the insulin analogues. Exercising the area of injection may cause the insulin to be absorbed more quickly due to increased blood flow to the exercising limb. In higher temperatures or when the area is warmed, such as by rubbing it, the insulin may be absorbed more quickly. Insulin type will also affect absorption. In general, the insulin analogues have less variability than conventional insulins. However, the absorption of NPH insulin is highly variable, especially with incomplete re-suspension of the insulin.
9. Note to the educator: Ask the group as a whole to discuss how insulin is used in their country. An idea might be to ask the participants to first discuss these questions in pairs, giving the individual participants a chance to clarify their own ideas and perceptions before opening the discussion to the whole group.
10. As mentioned earlier, there are various different insulin regimens. In a once-a-day regimen, intermediate acting insulin or a long acting analogue may be given either in the morning or at night. This insulin regimen may be used as a combination with oral antidiabetic medicines in the initiation of insulin therapy in type 2 diabetes. A short- or rapid-acting insulin could then be added either at the largest meal or before the meal that results in the highest post meal blood glucose values. The duration of NPH insulin is insufficient to provide 24-hour insulin coverage. The peak of this insulin at 8 to 10 hours after injection also places the person at increased risk of hypoglycaemia at this time.
11. The use of insulin twice a day is very common, especially in people with type 2 diabetes requiring insulin therapy. It is less suitable for use in type 1 diabetes. This regimen usually uses a soluble or rapid-acting insulin combined with an intermediate-acting insulin. This is often given using pre-mixed insulin, 30/70, 20/80, 40/60 or 50/50. As can be seen here, the intermediate-acting insulin given at breakfast and supper (dinner) time peaks in the early hours of the afternoon and night, putting the person at risk of hypoglycaemia at these times. This type of regimen requires the person to be consistent with meal times, to eat mid meal snacks and to be consistent with the amount of carbohydrate eaten. This is often inconvenient for the person with diabetes. This type of regimen is also associated with weight gain.
12. In many people with type 1 diabetes, the blood glucose level rises in the early morning (around 3 to 4 am) due to an increased secretion of growth hormone at this time. This is known as the “dawn phenomenon”. By delaying the timing of the intermediate-acting insulin to bedtime, instead of supper time, the peak action of the intermediate acting insulin is also delayed which may help minimise this blood glucose rise. It may also serve to reduce the risk of hypoglycaemia earlier in the night.
13. A basal-bolus regimen is traditionally called ‘intensive therapy’ or ‘multiple daily insulin’ (MDI). However, there are differences between these. Intensive therapy implies that a person knows how to adjust the dose of the bolus insulin based on their glucose levels, food to be eaten, and activity levels. In MDI, a person injects several times a day, but might not adjust the insulin based on blood glucose levels, food to be eaten or activity levels. Rapid-acting insulin is usually used as the bolus insulin for this regimen, although soluble insulin could be used if rapid-acting insulin is not available. Intermediate acting insulin is used once or twice a day to provide basal insulin coverage. In some people, a third smaller injection of intermediate-acting insulin is required at lunchtime to cover the dip in circulating insulin in the evening. As can be seen in this slide, this regimen more closely mimics normal physiological insulin secretion.
14. If a long-acting analogue is available, it can be used to replace the intermediate-acting in a basal-bolus regimen. The benefit of this approach is that there are no peaks and a steady amount of basal insulin is provided for 24 hours. It also decreases the number of injections. However, it should be noted that some long-acting insulin analogues need to be given twice a day to provide adequate 24-hour insulin coverage.
15. Insulin should never be positioned as a punishment for not having followed recommendations. It should be explained to people that as beta cell function declines, additional help is needed to keep the blood glucose level on target. The attitude of the health professional is often the key to the acceptance of insulin injections by the person with diabetes. Do not waste time having the person inject oranges or pads or other things. This simply delays the inevitable and ultimately increases tension. Stress and anxiety provoke cognitive roadblocks: a person who is anxious may not hear or take in all the technique instructions until after the injection. When teaching a person who is nervous, you may want to do the injection first, then go back and discuss technique.
16. The starting dose of insulin will depend on many factors. For example, insulin requirements of someone who is newly diagnosed with type 1 diabetes will be less than someone with a long history of type 1 diabetes as the newly diagnosed person will still be able to make some endogenous insulin. By comparison, adolescents, with large levels of growth hormone on board, often require a significantly higher insulin dose per kg of body weight than their adult counterparts. In people with type 2 diabetes who have not achieved glucose targets despite oral glucose-lowering medicines, weight gain and the amount of insulin required can be minimised by adding insulin to oral glucose-lowering medicines. In this case, a safe starting dose is 10 units of intermediate-acting insulin given once a day, either in the morning or before bed, depending on the time of greatest hyperglycaemia.
17. Insulin should be injected into subcutaneous tissue. In some people who are very thin, this may present a problem. A pocket into which the insulin can be injected may be provided by pinching an inch of skin and lifting it off the muscle. Insulin at room temperature is felt less by the individual and causes less pain than cold insulin taken straight from the fridge. Depending on the length of the needle, it should be inserted at a 45o to 90º angle (see next slide). If it is given at an angle of less than 45o, it will not be absorbed as well and may cause irritation at the site (if it is injected intradermally instead of subcutaneously). A thin person should inject at 45o to avoid injecting into the muscle. Injections into muscle hurt more and, due to increased blood flow to the muscle, will be absorbed faster. Swabbing with alcohol is not routinely used prior to injection in the home setting. However, if the person is living or working in an environment that is not clean, the area should be washed. If used, alcohol should be allowed to dry before the injection.
18. Hansen B. et al. (2006). Evidence-based guidelines for injection of insulin for adults with diabetes mellitus. 2nd Ed. Danish Nurses Organization.
19. Syringes and needles are usually disposable. The entire apparatus should be disposed of after a single use. However, for convenience, availability and cost, syringes are often re-used. In these cases, it should be stressed that the needle be used on only one person and the health risks of sharing needles with another person explained. If people are visually impaired, drawing up to a large line (every 5 or 10 units) can improve their drawing-up accuracy.
20. Pens are very convenient and easy to use and reduce dosage errors. However, some elderly people with diabetes may finding loading an new cartridge into the pen difficult. This can be helped by using disposable, pre-loaded pens.
21. Insulin pumps are small computerized devices that deliver small amounts of insulin continuously into subcutaneous tissue. The pump is programmed to give a slow continuous level of basal insulin. The basal insulin can be set at multiple rates across the 24-hour period to meet the individual needs of the person with diabetes. Insulin can also be given as a bolus to cover the post-meal blood glucose rise or to correct for high blood glucose levels. People with diabetes require extensive education and need an ongoing high level of commitment for pump therapy to be successful. They are also extremely expensive. Some pumps now “talk” to blood glucose meters through an infrared technology. This means the pumps recognized the blood glucose result and based on information inputted into the computer calculates the amount of insulin to be given as a bolus. The person has to confirm whether the dose is correct and if they want it given at that time. The pump does not know how much activity has been done or is planned or how much the person is planning to eat or when.
22. It is important that targets be individualised for people with diabetes depending on their specific needs. For example, the targets for young children or the elderly may be different from the average person. The targets in mmol/L are from the Canadian Diabetes Association Clinical Practice Guidelines. The targets in mg/dl are from the American Diabetes Association Clinical Practice Guidelines. IDF Clinical Guidelines Task Force. (2005). Global guideline for Type 2 diabetes. Brussels: International Diabetes Federation. IDF Clinical Guidelines Task Force. (2007). Guideline for Management of Postmeal Glucose. Brussels: International Diabetes Federation. American Diabetes association. (2010). Standards of Medical Care. Diabetes Care, 33(suppl 1), S19. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. (2008). Canadian Diabetes Association 2008 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. Can J Diab, 32(suppl 1).
23. Insulin is often started in people with type 2 diabetes by adding intermediate acting or long acting insulin between 10 and 11 pm. Benefits are that a smaller dose of insulin can be used than would be needed if the glucose-lowering medications were stopped and the person converted to insulin alone. Because of the smaller dose there may be less weight gain and less hypoglycemia than might be expected if switched to insulin alone. In some countries the use of insulin with TZDs is not approved and if used, people must be carefully monitored for fluid retention and increased weight. Riddle, M.C., Rosenstock, J., Gerich,J., the Insulin Glargine 4002 Study investigators. (2003). The Treat to Target Trial: randomized addition of glargine or human NPH insulin to oral therapy of type 2 diabetic patients. Diabetes Care, 26, 3080-86. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. (2008). Canadian Diabetes Association 2003 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. Canadian Journal of Diabetes, 32(suppl 1).
24. It is important to establish a blood glucose pattern before adjusting insulin. The timing of testing will depend on the type of diabetes and the insulin regimen being used. For example, a person with type 1 diabetes may be asked to test their blood glucose before and 2 hours after meals. However, for a person with type 2 diabetes, a single time of the day may be targeted. Once insulin therapy has been initiated, the dose will have to be adjusted. One way to adjust insulin is to teach the person with diabetes to carry out “pattern management.” In pattern management, it is important to keep meals, activity and medications as consistent as possible for a period of 3 days. The person should test their blood glucose frequently over the 3 days. The first thing to correct is hypoglycaemia. If the pattern shows hypoglycaemia at the same time every day, the insulin should be adjusted to prevent the blood glucose levels from falling excessively. If there is no hypoglycaemia, look next at the fasting levels. If the fasting levels are within the target ranges, the insulin may work better throughout the day. Adjustments should be made to achieve target fasting levels. The usual adjustment is 2 to 4 units at a time or 10% of the dose. It is usual to wait 2 to 3 days before making a further adjustment. Finally, make sure to consider post prandial glucose levels.
25. In life, one day is never the same as the next. Therefore, a person’s insulin needs may vary. People with diabetes should be advised how to adjust their own insulin for days of increased or decreased physical activity, late meals, or special events. In general, if a person is going to eat a larger meal than usual, they will require more insulin to cover the meal. Prolonged or sustained exercise helps muscle cells take up glucose. Therefore, people should be advised to decrease the insulin active at the time of exercise. Alternatively, they may like to snack before exercise. People with type 1 diabetes using a basal bolus approach should be taught to adjust their rapid-acting insulin to be proportional to the amount of carbohydrate eaten at each meal. Most adults require between 1 to 3 units of rapid-acting insulin per 15 g of carbohydrate (or 0.7 to 2 units per 10 g of carbohydrate). Most importantly, people have to adjust their doses to maintain optimal blood glucose levels through trial and error. They should be encouraged to learn from their blood glucose testing and to become proactive in preventing glucose excursions whenever possible.
26. This slide provides guidelines as to which insulin to adjust based on insulin action profiles and should be discussed at length with participants.
27. People are encouraged to keep a record of their blood glucose results. This is very helpful for the individual and for the health professional to be able to see what the blood glucose levels are and what makes the levels change. When helping people to start recording their results suggest they record them in a special book or on a lined paper. It is helpful to be able to see all the fasting results in one column, the pre-lunch in another column, and so on. See the next slides for examples.
28. Note to the educator: Ask participants to identify any blood glucose levels outside target and to suggest appropriate insulin adjustment.
29. Note to the educator: Ask participants to identify any blood glucose levels outside target and to suggest appropriate insulin adjustment.
30. The timing of the shorter-acting insulins in relation to a meal is important in order to maximise the effect of the insulin. Short acting (soluble or regular) insulin takes time to be absorbed. Therefore it should be injected 30-45 minutes before a meal. Rapid-acting insulin is absorbed quickly so it should be injected no more than 15 minutes before a meal. Ideally, it should be injected immediately prior to the meal. In some cases, such as when people are unsure of the amount to be eaten – as in young children – the rapid-acting insulin can be injected after the meal. In this way the insulin dose can be adjusted to appropriately cover the amount eaten. Intermediate- or long-acting insulin can be taken at any time and does not need to be taken in relation to food.
31. All insulin vials or cartridges have expiry dates printed on them. The expiry date indicates the date before which the unopened vial or cartridge should be used. Once the vial or cartridge is opened it should be discarded after one month, even if some insulin remains, as the potency of insulin will be lost over time. The potency of the insulin is also affected by cold and heat. Therefore insulin should not be frozen or stored in direct sunlight or heated areas. If a person is unable to prepare their own syringes, a family member can pre-draw the syringes and these can be stored in the fridge for up to one month. However, syringes should be rotated many times to re-suspend the insulin before the injection is given.
32. Insulin is made in several countries using several different manufacturing processes. Therefore, it is not all made to the same strength. The strength is denoted by the U system. U-40 means there are 40 units of insulin in 1 ml of solution. U-100 mean there are 100 units of insulin in every 1 ml of solution and so on. When using insulin of different strength, it is essential that the correct and matched unit syringes are used otherwise the person with diabetes may either over- or under-dose. The long-acting insulin analogues are clear, as are the soluble insulins. Therefore, it is very important when teaching people about their insulin to develop a way to differentiate the bottles.
33. NPH and soluble insulin can be mixed without changing the effectiveness or action of either of the insulins. In some countries it is permissible to mix other types of insulin in the same syringe. Check with the manufacturer of insulin in your country before mixing insulins other than NPH and soluble. The properties of one or other insulin may be altered by mixing.
34. Hypoglycaemia can occur in anyone using insulin therapy; however, it is more likely to occur in a person with type 1 diabetes, especially those who have a diminished counter-regulatory response. Insulin decreases fat breakdown and increases fat formation. Therefore weight gain is often associated with commencement or intensification of insulin therapy. It is also associated with excessive insulin doses. Therefore all people with diabetes commencing insulin therapy should be reviewed by a dietitian to minimise excessive or inappropriate weight gain. Lipohypertrophy is an abnormal build up of fat under the skin which can occur in areas of repeated insulin injection. This is a common side effect which can be minimised by asking people to rotate insulin injection sites. Lipoatrophy occurs due to loss of subcutaneous fat as a result of repeated injection. It is rarely seen with the use of human insulin. Other rare side effects include insulin oedema and insulin allergy. Insulin oedema is associated with commencement or intensification of insulin therapy in people with diabetes who are grossly underweight, who have had extended periods of poor control or who have been grossly under-insulinised. Allergic reaction usually takes the form of local swelling and reddening, but may be a systemic reaction. It may be due either to the preservatives or to the insulin itself.
35. These are some situations that are frequently encountered by people with diabetes. What would you advise? Eat something: hypoglycaemia is a risk if the meal is not eaten within 30 minutes of short-acting insulin or 15 minutes of rapid-acting insulin If the person has a hypoglycaemic episode immediately before the meal and the next dose of insulin: First, treat the low and re-test to be sure the blood glucose is above 4mmol/l (72mg/dl) The insulin should then be taken and the meal eaten as usual Some people might want to decrease the insulin dose, perhaps by 10%, to be sure to avoid another hypoglycaemic event The important thing is not to skip the insulin altogether 3. Exercise usually lowers blood glucose levels; therefore, less insulin is needed This person should reduce the amount of insulin regularly taken before lunch If there is no pre-lunch dose of insulin, the person might reduce the pre-breakfast intermediate-acting insulin The person should always be prepared with some fast-acting sugar source when exercising 4. If the person does not eat, should he/she take his/her insulin? Yes Test blood glucose: if over 14mmol/L (252mg/dl), check for ketones Try to drink sugar-containing foods at least every hour Perhaps omit the short- or rapid-acting insulin Take the intermediate-acting insulin 5. Blood glucose results are reading high or low and the person feels great; or the person feels low or high, yet the meter reads normal levels. Check the meter! Are the strips past the expiry date? Have the strips been left open to air? Is the test being done correctly? Is the meter reading mmol/L or mg/dl? (sometimes a person changes it inadvertently and then reads a 145mg/dl as 14.5mmol/L) Is the meter clean? Are the hands clean? Has the person lost the ability to discern hypos? (may be feeling well while levels are low)