› Initiate insulin for patients whose hemoglobin A1c ≥8% despite taking 2 or more oral agents. C
› Prescribe insulin for patients who have not reached their goal one year after diagnosis and initiation of oral therapy. C
› Consider reducing—but do not discontinue—oral agents, such as sulfonylureas and meglitinides, when you initiate insulin therapy. B
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
With type 2 diabetes now affecting 8.3% of the US population, most primary care physicians see patients with this disorder every day.1 Based on the concurrent obesity epidemic, aging population, and emergence of type 2 diabetes in children and adolescents, it is estimated that by 2050, the prevalence will have risen from one in 12 Americans to one in 3.1
Type 2 diabetes is a progressive disorder, with a relentless decline in beta cells. By the time of diagnosis, patients typically have lost at least 50% of insulin secretion; within 6 years of diagnosis, insulin secretion decreases to less than 25%.2
The American Association of Clinical Endocrinologists (AACE)3 and the American Diabetes Association/European Association for the Study of Diabetes (ADA/EASD)4 have recently published guidelines for the management of type 2 diabetes. While the AACE’s guidelines (available at https://www.aace.com/files/aace_algorithm.pdf) focus on different treatments at different stages of disease and both glycemic and nonglycemic benefits of treatment,3 the ADA/EASD’s guidelines (see http://care.diabetesjournals.org/content/early/2012/04/17/dc12-0413.full...) emphasize a patient-centered approach, shared decision making, and individualization of treatment goals based on both patient preference and comorbid disease states.4
One thing both sets of guidelines have in common is a purposeful intensification of therapy every 2 to 3 months, as needed, and the introduction of insulin one year after diagnosis if the patient is still not at goal.3,4 But all too often, this does not occur, particularly in primary care settings.
This article will review the “when” and “how” of insulin initiation. But first, a look at barriers to insulin therapy and evidence in support of earlier use.
Clinical inertia and patient fear are associated with delays
Both the AACE and the ADA/EASD guidelines agree that metformin is best used as early as possible.5,6 With typical use, however, metformin fails to prevent the progression of diabetes, as measured by the climb of hemoglobin A1c (HbA1c), at a failure rate of about 17% of patients per year.5 Physicians have been slow to intensify treatment for type 2 diabetes6—a phenomenon referred to as clinical inertia.
Typically, physicians adopt a stepwise approach, which often results in patients spending more than 10 years with an HbA1c >7% and 5 years with an HbA1c >8% before insulin is started.5 In a recent Veterans Administration study, patients were out of control, with an HbA1c >8%, for an average of 4.6 years before insulin was initiated.7
Both patient and physician factors contribute to the delay. Patient factors include the fear of injection, the belief that insulin will interfere with their lifestyle, and the idea that the use of insulin signifies impending complications or even death.8 But such beliefs are starting to change. In a recent multinational study of patients with type 2 diabetes, less than 20% stated they were unwilling to start insulin.9
For their part, primary care physicians are much less likely to prescribe insulin than clinicians specializing in diabetes.6 Physician-reported barriers to insulin initiation include the time required to train patients to use it correctly; the lack of support, including access to diabetes educators; and the absence of clear guidelines on the use of insulin.10
A case for earlier insulin
There has been recent momentum in favor of earlier initiation of insulin. In fact, some researchers regard intensive insulin as an excellent first treatment for type 2 diabetes,11 based on the belief that early insulin (used for a brief time) can provide not only immediate improvement in glucose control, but also a lasting “legacy” effect. The ADA/EASD guidelines support the use of insulin as a first-line treatment for patients with symptoms of insulin deficiency,4 but do not recommend it for everyone with newly diagnosed type 2 diabetes.
There have also been a number of advances in insulin therapy over the past 2 decades. These include insulin analogs with physiologic profiles that better match daily schedules, as well as improvements in the way insulin is delivered. Insulin pens, smaller needles, disposable devices, and insulin pumps have made it easier to administer and fine-tune insulin delivery. Despite these improvements and recommendations for earlier implementation, the use of insulin in type 2 diabetes is significantly lower today than in the 1990s.12