Starting insulin in patients with type 2 diabetes: An individualized approach

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ABSTRACTBecause type 2 diabetes mellitus is a progressive disease, most patients eventually need insulin. When and how to start insulin therapy are not one-size-fits-all decisions but rather must be individualized. This paper reviews the indications, goals, and options for insulin therapy in type 2 diabetes.


  • In deciding a patient’s hemoglobin A1c goal and whether it is time to start insulin therapy, one should take into account the patient’s age, life expectancy, concurrent illnesses, risk of hypoglycemia, and other factors.
  • When the target hemoglobin A1c is not achieved with metformin or a two-drug regimen that includes metformin, the American Diabetes Association recommends adding a daily dose of basal insulin.
  • Eventually, preprandial bolus doses may need to be added to the insulin regimen to control postprandial blood glucose levels and hemoglobin A1c.



Insulin therapy is one of the most effective tools clinicians can use to help patients reach their individualized hemoglobin A1c target. However, decisions about when and how to start insulin therapy have to be individualized to the needs and goals of each patient. Many insulin options are available, one of the most common being the addition of basal insulin to oral antidiabetic drugs. Although patients are often reluctant to start insulin, this reluctance can be overcome through patient education and hands-on training.

Here, we review hemoglobin A1c targets, factors that determine when to start insulin therapy, and the different regimens that can be used.


Type 2 diabetes mellitus is a chronic progressive disease associated with insulin resistance, beta-cell dysfunction, and decreased insulin secretion. Consequently, most patients eventually require insulin therapy to reduce the risk of long-term complications.

The efficacy of therapy can be assessed by measuring hemoglobin A1c, an important marker of the chronic hyperglycemic state. The hemoglobin A1c value can be reported as a ratio (%) standardized against the results of the Diabetes Control and Complications Trial,1 or as International Federation of Clinical Chemistry units (mmol/mol).2Table 1 shows the relationship between hemoglobin A1c and average glucose values.3


The short answer is, “It depends.”

Currently, the American Association of Clinical Endocrinologists (AACE) supports a hemoglobin A1c goal of less than 6.5% for otherwise healthy patients but states that the goal should be individualized for patients with concurrent illnesses or at risk of hypoglycemia.4

On the other hand, the American Diabetes Association (ADA) recommends a higher hemoglobin A1c target of less than 7% for most adults with type 2 diabetes mellitus.5 This value was shown to be associated with a reduction in the microvascular and macrovascular complications of diabetes.

Yet when three large trials6–8 recently compared intensive and standard glucose control regimens, tighter glucose control failed to improve cardiovascular outcomes. Moreover, in one of the trials,7 patients receiving intensive treatment had a higher rate of all-cause mortality. Details:

  • Action in Diabetes and Vascular Disease (ADVANCE): 11,140 patients; average hemoglobin A1c levels 6.5% vs 7.3%6
  • Action to Control Cardiovascular Risk in Diabetes (ACCORD): 10,251 patients; average hemoglobin A1c levels 6.4% vs 7.5%7
  • Veterans Affairs Diabetes Trial (VADT): 1,791 patients; average hemoglobin A1c levels 6.9% vs 8.4%.8

Similarly, a 2013 Cochrane review9 that included 28 randomized controlled trials concluded that intensive control (in 18,717 patients) did not decrease all-cause and cardiovascular mortality rates compared with traditional glucose control (in 16,195 patients), and it increased the risk of hypoglycemia and serious adverse events.

The AACE and ADA are moving away from one-size-fits-all and toward individualized recommendations

As a result, the ADA5 states that a hemoglobin A1c target less than 6.5% is optional for patients with a long life expectancy, short duration of diabetes, low risk of hypoglycemia, and no significant cardiovascular disease. The ADA further defines a hemoglobin A1c goal of less than 8% for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, extensive comorbid conditions, and long-standing diabetes.

Therefore, the AACE and ADA are moving away from “one-size-fits-all” goals and toward individualizing their recommendations.

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