Insulin therapy for type 2 diabetes: Making it work

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Applied Evidence

Insulin therapy for type 2 diabetes: Making it work

J Fam Pract. 2010 April;59(4):E1-E8

By

Jody Dushay, MD

Martin J. Abrahamson, MD

Initiating and advancing insulin therapy in patients with type 2 diabetes can be challenging. Here’s how to overcome the barriers that may arise.

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References

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PRACTICE RECOMMENDATIONS

• Inform patients with type 2 diabetes about the possible need for insulin therapy if diet, healthy lifestyle, and medications other than insulin do not achieve glycemic control. A

• Add basal insulin to oral medications as soon as needed to help patients reach fasting glycemic goals. If further adjustments are needed, add prandial insulin. B

• Choose basal and prandial insulin analogs to approximate normal physiologic insulin secretion. C

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

Many patients with type 2 diabetes will eventually require insulin to reach glycemic targets that have been shown to protect against micro- and macro-vascular complications of the disease. But in the primary care setting, initiating and advancing insulin therapy for these patients can be challenging. This article discusses the barriers to initiating insulin therapy that family physicians often encounter and suggests strategies for addressing them. The goal should be to approximate normal physiologic insulin secretion as closely as possible. We will outline how that goal can best be achieved using combinations of long-acting and rapid-acting insulin analogs in a variety of basal-prandial regimens.

The evidence behind good glycemic control
Several landmark trials, including the United Kingdom Prospective Diabetes Study (UKPDS), the Diabetes Control and Complications Trial (DCCT), the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC), and the recent ADVANCE study, demonstrate the importance of good glycemic control in reducing the risk of microvascular complications of diabetes.^1-4 These studies all show that lower glycosylated hemoglobin levels (hemoglobin A1C) are associated with a reduction in risk for the development or progression of microvascular complications of the disease.^1-4

Setting glycemic targets

The American Diabetes Association (ADA) and the American Association of Clinical Endocrinologists (AACE) have established guidelines that provide physicians and patients with glycemic targets. The ADA recommends that hemoglobin A1C be maintained at <7.0% or as near normoglycemia (<6.0%) as possible without significant risk of hypoglycemia. Preprandial glucose targets are 70 to 130 mg/dL, and the postprandial target is <180 mg/dL.⁵ The AACE recommends even stricter glycemic control, with an A1C target of <6.5%, a preprandial target of ≤110 mg/dL, and peak postprandial glycemic target of ≤140 mg/dL.⁶ In clinical practice, it is best to aim for glycemic targets that are as close to ADA or AACE guidelines as possible, provided one can do so safely. In doing so, the clinician must recognize that glycemic goals should be individualized, to take into account the presence of comorbid conditions and the expected longevity of the patient.⁷

Glycemic control in type 2 diabetes. Diet, exercise, weight loss, and adoption of a healthy lifestyle are the cornerstones of care for patients at all stages of diabetes. As the disease progresses, most patients with diabetes will also require pharmacologic therapy that will need to be intensified over time.⁸

FAST TRACK

In clinical practice, insulin therapy is often delayed because of misconceptions and fears about disease progression and the role of insulin.

Oral agents are the place to begin. Typically, pharmacologic management of diabetes begins with oral agents.⁸ Several categories of oral medication can be used to treat type 2 diabetes, and more than 1 agent may be used for initial treatment of hyperglycemia. Insulin secretagogues (sulfonylureas and meglitinide analogs) are prescribed to treat the insulin secretory defect, whereas insulin sensitizers (metformin and thiazolidinediones) are used to address insulin resistance. Other agents include a-glucosidase inhibitors, which benefit patients with type 2 diabetes by slowing carbohydrate absorption, while glucagon-like peptide-1 (GLP-1) analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors increase incretin levels, enhance insulin secretion in a glucose-dependent manner, and suppress pancreatic glucagon secretion.

When adding insulin becomes necessary

FAST TRACK

To help guide your decision making, consider the AACE/ACE Diabetes Algorithm for Glycemic Control, an updated guide for moving from oral medications to insulin therapy.

Even when combinations of these medications are used, many patients ultimately require the addition of exogenous insulin to achieve glycemic control.⁹ In clinical practice, however, insulin therapy is often delayed because physicians and patients alike are prey to misconceptions and fears about disease progression and the role of insulin.¹⁰ TABLE 1 presents some of the most common preconceptions held by patients about the initiation of insulin therapy, and suggests strategies for overcoming each of them.¹¹

To help guide your decision making, you can follow the AACE/ACE Diabetes Algorithm for Glycemic Control, an updated guide for moving from oral medications to insulin therapy, depending on A1C levels. The algorithm is available at http://www.diabetesincontrol.com/images/issues/2012/04/aace_guidelines_for_glycemic_control.pdf.¹²