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DOI: 10.1177/0145721705285640 © 2006 American Association of Diabetes Educators; Published by SAGE Publications
Systematically Initiating InsulinThe Staged Diabetes Management ApproachFrom the International Diabetes Center, Minneapolis, Minnesota. Correspondence to Jan Pearson, BAN, RN, CDE Director, International Diabetes Center, 3800 Park Nicollet Boulevard, Minneapolis, MN 55416.
These questions often arise when considering insulin therapy for a patient with type 2 diabetes and will be addressed in this article. To begin, it is important to understand the disease course of diabetes. The natural progression of type 2 diabetes (Figure 1) suggests that 60% of persons with this disease will eventually require insulin therapy to adequately control blood glucose levels.1 Studies show that the use of a systematic approach to type 2 diabetes care focused on treating to target can improve blood glucose control.2-4
Diabetes educators play a key role in recommending and initiating insulin therapy in this population. Available protocols help guide this process and allow health care professionals to become more comfortable and experienced with the process. In addition, when protocols become approved as management guidelines within a health care system, 2 important results occur that facilitate the use of insulin therapy. One is that diabetes educators are authorized to provide care according to guidelines, and the other is that patients hear a consistent message about insulin therapy. Clinical guidelines that are available include Staged Diabetes Management (SDM) Decision Paths. First published in 1995 by the International Diabetes Center (IDC), SDM set forth the first comprehensive guidelines on the management of diabetes. The fourth edition of these guidelines was published in 2005.5 SDM is based on a systematic evidence- and practice-based approach to managing diabetes in the primary care setting.
Rationale for Insulin Therapy in Type 2 Diabetes A rise in postmeal glucose levels occurs even before an individual is diagnosed with type 2 diabetes. The individual's pancreatic ß cells begin to work overtime to produce insulin to control this prediabetic rise in glucose levels. With time, insulin resistance increases, and the ß cells can no longer compensate for the rise in fasting and postmeal glucose excursions. This is when the diagnosis of diabetes is made. Initial therapies in individuals with prediabetic tendencies often begin with nutrition and exercise; oral agents such as metformin and the thiazolidinediones (TZDs) may be added to address insulin resistance. With the diagnosis of type 2 diabetes, secretagogues are often prescribed to supplement insulin release. As the disease progresses, there will be a continuing decline in insulin secretion within 6 to 10 years of diagnosis (this may be seen even earlier in patients who may have had diabetes years before their diagnosis was made). An inability to achieve target glucose goals is an indication that oral agents (particularly secretagogues) are no longer effective and insulin therapy is required. Once insulin therapy is initiated, TZDs and metformin are often continued because of their benefit in targeting insulin resistance.
Insulin is one of the most effective yet most under-used therapies in the management of type 2 diabetes. The goal of insulin therapy is to mimic physiologic insulin secretion and achieve normoglycemia in an effort to reduce the risk of long-term diabetes complications. (In September 2005, the IDC reduced their recommended fasting and premeal blood glucose targets from 70-140 mg/dL [3.85-7.7 mmol/L] to 70-120 mg/dL [3.85-6.6 mmol/L] for type 2 diabetes.) Ultimately, the role of insulin is to increase the uptake and use of glucose by muscle and adipose tissue. It is important to communicate to the patient that insulin is safe and effective for lowering blood glucose levels.
Normal Physiologic Response of Insulin to Food It is important to note that due to their similarity the terms basal and bolus insulin can be confusing especially for patients learning about insulin. At IDC and throughout this article, the terms background and mealtime are used in place of basal and bolus, respectively.
Patient and Glycemic Factors A systematic approach for insulin initiation is necessary, and there are a variety of factors that affect the selection of an insulin regimen for an individual patient. These factors can be grouped together into 2 categories: patient factors and glycemic factors (Table 1). It is critical that the clinical assessment of the patient with diabetes include a review of the patient factors that need to be considered when determining the selection of an insulin regimen. These factors include patient willingness to implement a specific insulin regimen, comfort level, ability (visual acuity, dexterity, and cognitive skills), and lifestyle factors (eating habits, physical activity, and schedule).
Discussing and exploring patient factors help prepare a patient for initiating insulin as this process allows questions and concerns about insulin therapy to be raised by the patient and the health professional. This step is often overlooked in many patient education materials. Evaluation of glycemic factors (current A1C levels, self-monitored blood glucose [SMBG] data, and current medications) also influences the selection of an insulin regimen—and the method—of administration (eg, insulin pen, syringe, or pump). In some cases, the evaluation of glycemic factors may indicate the need for a particular insulin regimen; however, patient factors may be a contraindication for selection of the same regimen. The initial regimen is the starting regimen and can most certainly change as the patient demonstrates a willingness, comfort, and ability to do so.
Primary Insulin Regimens
There are 3 primary insulin regimens (Figure 2) that are used when starting insulin in a patient with type 2 diabetes: (1) background insulin and oral antidiabetic agents, (2) premixed insulin, and (3) background and mealtime insulins. Background and mealtime insulin therapy is considered the gold standard of insulin therapy; however, this regimen requires that the patient be highly motivated and also requires a significant amount of time devoted to teaching the patient as well as time devoted to support and follow-up. Patients often do not like the idea of this regimen and may not be willing to start insulin therapy with 4 injections per day; however, this number of injections is not always necessary. Consideration should be given to initiating insulin therapy with 1 to 2 injections per day and adjusting therapy as barriers to additional injections are overcome or if glycemic control indicates a critical need to change regimens. The objectives of the first few weeks of insulin therapy are to familiarize patients with insulin administration, build patient confidence, and to start to improve blood glucose control. At a later point, patients may be more receptive to the idea of additional injections to cover background and mealtime needs, particularly if they want increased flexibility with respect to food choices and daily activity schedule.
Background Insulin and Oral Agents Today, the use of background insulin with oral antidiabetic agents is a relatively common approach to initiating insulin therapy. Fasting glucose levels are targeted with background insulin and oral agents address mealtime glucose excursions. Table 1 lists factors to be taken into consideration when deciding to use background insulin with oral agents.
The SDM uses body weight and A1C levels as a preferred method to determine
the appropriate starting dose: 0.1 U/kg body weight if A1C levels are <9%
or 0.2 U/kg body weight if A1C levels are When starting this regimen, the fasting blood glucose value guides the titration of background insulin (Table 3). Nutrition and diabetes education are important when beginning this regimen.
The Treat-to-Target trial showed that 60% of study participants achieved an
A1C level of
In the Treat-to-Target study, doses were titrated from the initial dose. At
the end of the study, the average final dose among patients achieving the A1C
goal of
Premixed Insulin ± Sensitizers Knowing the relative contribution of fasting blood glucose (FBG) levels and postprandial glucose levels to A1C levels allows clinicians to make more informed decisions about therapy. For example, if a patient's A1C level is 7.5% and FBG levels are nearing target but postprandial levels are high, then attention needs to be given to lowering postprandial levels. Three studies have compared twice-daily premixed insulin analogs (both lispro and aspart) to once-daily insulin glargine in patients who were also receiving metformin.4,9,10 The results of all 3 trials show that when A1C values are still above but close to target, greater attention should be paid to lowering postprandial values than to lowering FBG values alone. Insulin secretagogues should be discontinued when treatment with premixed insulin is initiated as premixed insulins are able to cover postmeal glucose excursions. Insulin sensitizers can be added or continued to address insulin resistance. As with the background insulin regimen, the higher the patient's A1C level, the higher the recommended starting dose of premixed insulin (Table 4). Premixed insulin is given before breakfast and dinner, and adjustments are based on fasting and predinner SMBG testing. As with all insulin treatment strategies, titration needs to occur at regular intervals until glycemic goals are achieved. Typically, only 1 insulin dose is titrated at a time; it can be either the breakfast or predinner dose, whichever one has more potential for addressing the greatest elevation.
Some patients prepare their own self-mixed insulin wherein they combine intermediate-acting insulin with a rapid- or short-acting insulin in a single syringe. The benefit of this regimen over a premixed regimen is that the patient has the ability to adjust the mealtime insulin dosage. However, self-mixed insulin regimens require the use of syringes, whereas premixed insulins are available in more convenient pen devices and require no daily adjustment by the patient.
Background and Mealtime Insulin ± Sensitizers This regimen is most beneficial and often highly desirable for those who want flexibility in their carbohydrate intake and for those who want to vary the time of their meals, the ability to quickly respond to high blood glucose levels, and/or have a variable activity pattern. The insulin dose calculation for this regimen is similar to that of other regimens and is based on the current A1C level and body weight (Table 5). It is important to note that 2 doses are calculated. The first dose is for the background insulin, which provides a steady amount of insulin throughout the day and is given at about the same time each day. This insulin can be given at any time of day as long as it is at approximately the same time each day (ie, within 1 hour). Most often it is given at bedtime or in the morning.
Background insulin accounts for approximately 50% of the total daily insulin need, and mealtime insulin (given in divided doses) makes up the other 50% of the total daily need. The total daily dose targeted for mealtimes can be divided equally if carbohydrate intake is fairly equally distributed or may be adjusted to match the relative size of each meal. Blood glucose levels will guide the exact dosages to be taken at each meal. However, when this regimen is first initiated, dosages may need to be established prior to knowing a patient's exact carbohydrate intake and before the patient can be fully educated about carbohydrate counting. In these cases, the initial amount of insulin is usually set to be high enough to have a lowering effect on blood glucose levels but low enough to avoid hypoglycemic events. Thus, a brief discussion with the patient about usual mealtimes and quantities of food should give the educator/provider enough information to determine the initial doses of insulin to be taken at mealtimes. There are several instances in which the insulin dose-distribution profile might vary, such as when someone is very athletic or has a high carbohydrate intake. These situations may require a ratio of 40% background insulin and 60% mealtime insulin. Blood glucose levels should be monitored at a minimum of 4 times a day: before breakfast, lunch, and supper and again at bedtime. See Table 5 for guidelines on adjusting insulin doses. Once most daily blood glucose levels are below 200 mg/dL (11 mmol/L), patients should be asked to check glucose levels 2 hours after the start of the meal to ensure that the postmeal blood glucose goal of <160 mg/dL is met. If the 2-hour postmeal glucose exceeds the 160 mg/dL target, increase mealtime insulin 1-2 units if 160-240 mg/dL, and 2-4 units if >250 mg/dL. The aim for patients who take a mealtime insulin is to see no more than a 40 mg/dL (2.2 mmol/L) difference from the premeal to the postmeal blood glucose values. For example, if the premeal blood glucose level is 95 mg/dL (5.2 mmol/L), the 2-hour postmeal goal should be <135 mg/dL (7.4 mmol/L). The goal of diabetes therapy is to achieve near-normal glycemia without wide fluctuations in blood glucose values.
There are times when patients are started on one insulin regimen and then move to another regimen. This section reviews 2 such situations.
Moving From Premixed Insulin to Background/Mealtime Insulin If the patient has not been taking an insulin sensitizer with premixed insulin, it can be added now. In addition, as with the initiation of any insulin regimen, time should be devoted to reinforcing the principles of healthy food intake and activity. If the patient has not had carbohydrate-counting education, the first step would be to introduce consistency with carbohydrate intake. Adequate follow-up should be provided to ensure understanding. Depending on the patient's readiness, introduction to insulin-to-carbohydrate ratio would follow to maximize therapy.
Adding Mealtime Insulin to Background Regimens When this switch is being made, confirm that the patient is able to implement carbohydrate counting or has a consistent carbohydrate intake. If this is not the case, ensure that adequate education and support is provided for carbohydrate counting. High amounts of insulin may be required even when used in combination with insulin sensitizers because of high levels of insulin resistance.
Follow-up for New Insulin Starts
Food and Exercise Adjustments
Nutrition Records and Making Adjustments to Insulin Dose Based on Food Intake
Nutrition therapy is essential for any person taking insulin. This requires initial assessment, education, and adequate follow-up to determine the appropriateness of recommendations and ease of implementation. Lack of nutrition follow-up has been shown to result in increases in A1C levels (Figure 3). The general approach to nutrition therapy with someone who is taking insulin is carbohydrate counting. Even if someone has previously had general nutrition education or specific education in carbohydrate counting, it is still important to review the concepts of carbohydrate counting in light of the specific insulin regimen that he or she is following. Table 6 summarizes the general nutrition principles for the 3 primary insulin regimens.
The natural history of diabetes indicates that insulin therapy will eventually be needed by the majority of persons with type 2 diabetes. A systematic approach presented in a positive, supportive manner helps facilitate the initiation and acceptance of insulin therapy by the patient. The goal of insulin therapy is to mimic the physiologic action of insulin. Patient and glycemic factors should be considered when selecting the initial insulin regimen. Successful implementation of insulin-based treatment strategy depends on (1) initiating insulin treatment when it is appropriate, (2) titrating insulin levels to achieve A1C and glucose goals, and (3) ensuring that patients feel comfortable in administering and monitoring their own therapy.
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Introduction
Selecting an Insulin Regimen
9%. (At the time of publication,
the IDC was favorably considering the adoption of more aggressive insulin
initiation guidelines: 0.1 U/kg per dose if A1C levels were <8%; 0.2 U/kg
per dose if A1C levels were 8%-10%; 0.3 U/kg per dose if A1C levels were
>10%. Note that when premixed insulin regimens are used, 2 doses of insulin
are needed each day. For example, someone with an A1C level of 9% on a
premixed regimen requires a 0.2-U/kg dose at breakfast and a 0.2-U/kg dose at
dinner. The total daily insulin dose would be 0.2 U with A1C levels <8%,
0.4 U with A1C levels of 8%-10%, and 0.6 U with A1C levels >10%.) Insulin
is prescribed either in the morning or at bedtime based on the patient's
schedule. It is important to note that although insulin glargine can be taken
at any time during the day, it should be injected at a similar time each day.
Some patients may consider splitting their background insulin dose if coverage
does not appear to last 24 hours, and this affects blood glucose control. 
7.0% with a single injection of insulin glargine or NPH in
combination with oral
agents.