Contributions of fasting and postprandial plasma glucose levels to glycosylated hemoglobin and diabetes mellitus-related complications: Treating hyperglycemia with insulin

Abstract

Background: Glycosylated hemoglobin (A1C) is a good indicator of a patient's mean plasma glucose level over the previous 90 to 120 days. It can assist in determining whether fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) levels are under control in a patient with diabetes mellitus. Self-monitoring of blood glucose levels is essential to distinguish the contributions of FPG and/or PPG when a change occurs in the AIC level. Objectives: The goal of this article was to define A1C and address the contributions of FPG and PPG levels to overall A1C. Elevated A1C levels correlate with an increased risk of cardiovascular disease and other complications, which are also reviewed here. Available therapies and therapeutic strategies are discussed, including the use of insulin when oral therapy alone has not maintained glycemic control. Methods: English-language articles (1990–2006) were searched on the PubMed database using the following terms: insulin, type 2 diabetes, early insulin use, A1 C, and hemoglobin A1 C. Results: Several studies are presented here which demonstrate that blood glucose levels can dramatically improve when insulin is added to the existing regimen of oral therapy or when administered alone. In recent trials, active titration of the insulin dose to treatment target levels has been effective in improving the overall glycemic profile. Insulin glargine and insulin detemir, long-acting insulin analogues, are safe and effective and can be used initially as basal insulin with oral agents or with prandial insulin (regular human insulin or a rapid-acting insulin analogue [eg, insulin lispro, insulin aspart, insulin glulisine]) if glucose levels are not well controlled with basal insulin plus oral agents. Basal-prandial insulin regimens that utilize both long-acting and rapid-acting insulin analogues most closely resemble normal pancreatic insulin secretion and are effective in allowing patients to achieve recommended glycemic targets. Conclusions: Early and persistent intensification of therapy designed to achieve glycemic goals, including the use of oral agents and/or insulin, should be initiated at diagnosis and appropriately titrated. The contributions of FPG and PPG to overall A1C should be closely monitored so that the most appropriate and effective treatment regimen may be implemented.