The Continuation of Oral Medications with the Initiation of Insulin Therapy in Type 2 Diabetes: A Review of the Evidence

M. Shawn McFarland, PharmD; Tara N. Knight, PharmD; Andrea Brown, PharmD; Jeremy Thomas, PharmD


South Med J. 2010;103(1):58-65. 

In This Article

Abstract and Introduction


The combination of oral medications with insulin is inevitable in the treatment of type 2 diabetes. Unfortunately, there are no consensus statements available to guide the continuation or discontinuation of specific therapies. The clinician treating the type 2 diabetic patient must be aware of the literature regarding use of oral medications in combination with insulin.


The treatment of type 2 diabetes has become ever increasingly complex with the introduction of newer oral therapies to the market. Because of the progressive nature of the disease process in type 2 diabetes, the use of insulin is often required in treatment either alone or in combination with oral medications.[1] Once insulin is initiated simplification of the oral medication regimen is often needed and at times required. Continuation of oral medications with insulin is often based on the possibility of improvement of glycemic control once insulin is initiated. There is no consensus as to what medications are continued once insulin is initiated and the decision to continue or discontinue oral medications is guided by the past experiences of the clinician.

The American Diabetes Association and the European Association for the Study of Diabetes (ADA/EASD) have released a consensus algorithm for the initiation and adjustment of therapy as a guide to the treatment of type 2 diabetes. The guidelines are based on clinical trials evaluating efficacy and safety, as well as on clinical judgment taking into account benefits, risks, and costs in the treatment of type 2 diabetes. The initiation of basal insulin is now considered a well-validated tier 2 treatment in the ADA/EASD consensus algorithm, with the possibility of progressing to a more intensive insulin regimen as needed in the future. In our experience, most providers will delay initiation of insulin until other oral treatments have failed for fear of inducing hypoglycemia, increasing weight gain, or the perceived complexity of the regimen to the patient and the provider. The ADA/EASD guidelines do not address continuation or discontinuation of oral medications once insulin is begun.

This article will review the evidence associated with the continuation of specific oral medications in combination with insulin. We will focus on (1) improvement of glycemic control with insulin, (2) risk of hypoglycemia with insulin, (3) weight gain with insulin and (4) cost. We hope to provide the clinician treating the diabetic patient requiring oral medications and insulin in combination a literature guided approach as to whether continuation or discontinuation of oral therapies should be considered.


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