Type 2 diabetes. Most people with type 2 diabetes will eventually need insulin to achieve target A1C values (Wright 2002). The U.K. Prospective Diabetes Study (UKPDS) showed that b-cell failure is progressive; there is 50% normal b-cell function at diagnosis, with a steady decline after diagnosis (DeWitt 2003; UKPDS 1998). It is also reported that 53% of people with type 2 diabetes initially treated with sulfonylureas require insulin therapy by 6 years, and almost 80% require insulin by 9 years (Turner 1999; Wright 2002).
A small clinical trial examined metabolic control and patient preference in people with type 2 diabetes using conventional “fixed” or flexible insulin therapy (Kloos 2007). The authors concluded that initiation of insulin therapy was safe and effective in both treatment options, but after initially improving glycemic control, neither group achieved A1C levels <7%. After 8 weeks of following both the fixed and flexible insulin plans, the participants stated that they preferred the last therapy they received.
The first randomized study to evaluate intensive basal-bolus analog insulin therapy in people with type 2 diabetes as well as efficacy of carbohydrate counting in this population was conducted in 2008 (Bergenstal 2008). The simple algorithm group was provided with a set dose of prandial insulin to take before meals and compared to a group instructed on carbohydrate counting by an RD who provided an ICR to use for each meal. Prandial and basal insulin levels were adjusted weekly in both groups on the basis of SMBG results from the previous week. A1C levels at the end of study were 6.7% (simple algorithm) and 6.54% (carbohydrate counting). The respective mean A1C changes from baseline to 24 weeks were –1.46 and –1.59% (P = 0.24). Both groups used SMBG results to dose insulin. The simple algorithm group participants either consumed fairly consistent amounts of carbohydrates, thus minimizing needed changes in insulin dosing, or learned to modify their carbohydrate intake on the basis of SMBG results.
Factors That May Affect Long-Term Adherence to Basal-Bolus Insulin Regimens
Three studies exploring the food and eating practices of people with type 1 diabetes converted to FIIT as part of the DAFNE course have been published (Lawton 2011; Rankin 2011; Casey 2011). One study reported that adoption of this type of insulin treatment plan can result in greater dietary rigidity over time as opportunities presented for greater dietary freedom are counterbalanced by new challenges and burdens (Lawton 2011). For example, in an effort to simplify food choices for easier carbohydrate estimation, the individual may rely on prepackaged foods that include nutrition fact information rather than on naturally occurring, unprocessed foods such as fresh fruits and vegetables that do not have food labels. This step could lead to increased consumption of saturated fats and salt. FIIT participants also articulated anxieties about miscalculating carbohydrate amounts and injecting the wrong dose, resulting in the tendency to eat the same things over and over again, limiting intake of new foods or foods with difficult-to-determine carbohydrate content. Some participants purposefully choose low-/no-carbohydrate foods to safely simplify calculations of prandial doses. Despite participation in formal intensive insulin therapy classes, fear of hypoglycemia when matching mealtime insulin to desired food (carbohydrate) intake continues to be a concern for many (Lawton 2011).
Another investigation over 12 months explored participant experiences regarding how they sustain use of FIIT (Rankin 2011). Although patients generally preferred flexible insulin therapy to conventional or “fixed” insulin therapy, the therapy had several constraints. Participants found that they had to make some adjustments to their lives to sustain this method of treatment, such as maintaining a similar weekday schedule on the weekends, adjusting food choices, or by creating food habit routines. The researchers suggested that diabetes education programs need to include interventions or strategies that can help patients successfully convert to FIIT long term.
The third group of researchers interviewed DAFNE program participants and collected information at 6 weeks and 6 and 12 months on how they assimilated course principles over time (Casey 2011). Participants initially (6 weeks) felt support from other participants, for example, by sharing experiences. However, after 6 months, participants began to value support from responsive health care professionals that focused on collaborative decision-making. The authors concluded that there is a need for diabetes educators to clearly communicate and explain to participants that adoption of the FIIT principles takes time (perhaps over 12 months). Support at 6 months appeared to be an important timeframe for participants, since motivation at this point was lowest for many.
People with insulin-requiring diabetes may also diligently perform dose calculations using their individualized algorithms when beginning intensive insulin therapy (Gross 2003). However, adherence to the ongoing determination of the prandial insulin dose may become relaxed as the person with diabetes gains familiarity with the self-adjustment of the insulin. As time passes, there may be the tendency to begin to approximate premeal doses by titrating insulin based on the “standard” or “usual” carbohydrate content of the meal. In addition, many people with insulin-requiring diabetes may actually be hesitant to take on the responsibility of increasing or decreasing their insulin doses on the basis of their carbohydrate intake and premeal blood glucose level (Gross 2003).
It is important to remember that timing of the insulin dose as well as prandial and correction algorithms are just a starting point when initiating or using insulin therapy plans for individuals with insulin-requiring type 1 or type 2 diabetes. Algorithms for flexible insulin dosing or fixed insulin dose prescriptions will not be effective if the individual self-managing his or her diabetes does not possess a thorough understanding of appropriate actions to implement. Also important is the daily incorporation of the carbohydrate-counting meal-planning approach or another method of accurately quantifying carbohydrate intake. Insulin doses need to be confirmed by one of the cornerstones of diabetes self-management—blood glucose monitoring. Finally, the individual with insulin-requiring diabetes has been shown to benefit from regular interaction with responsive and supportive diabetes health care professionals to effectively optimize blood glucose control to reduce the risk of long-term complications of poorly controlled diabetes.
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