Postprandial glucose regulation: New data andnew implications

Abstract

Background: Type 2 diabetes is characterized by agradual decline in insulin secretion in response to nutrient loads; hence, it is primarily a disorder of post-prandial glucose (PPG) regulation. However, physicians continue to rely on fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) to guide management Objectives: The objectives of this article are to review current data on postprandial hyperglycemia and to assess whether, and how, management of type 2 diabetes should change to reflect new clinical findings. Methods: Articles were selected from MEDLINE searches (key words: postprandial glucose, postprandial hyperglycemia, and cardiovascular disease) and from our personal reference files, with emphasis on the contribution of postprandial hyperglycemia to overall glycemic load or cardiovascular (CV) risk. Results: About 33% of people diagnosed as having type 2 diabetes based on postprandial hyperglycemia have normal FPG. PPG contributes ≥70% to the total glycemic load in patients who are fairly well controlled (HbA, 1c ≤.3%). Furthermore, there is a linear relationship between the risk of CV death and the 2-hour oral glucose tolerance test (OGTT). Increased mortality is evident at OGTT levels of ∼90 mg/dL (5 mmol/L), which is well below current definitions of type 2 diabetes. Biphasic insulin aspart was shown to be more effective at reducing HbAlc below currently recommended levels than basal insulin glargine (66% vs 40%; P < 0.001), and it reduced endothelial dysfunction more effectively than regular insulin ( P < 0.01). Repaglinide achieved regression of carotid atherosclerosis (intima-media thickness) in 52% of patients versus 18 % for glyburide ( P < 0.01) over 1 year, although levels of HbAlc and CV risk factors were similar for both treatment groups. Finally, acarbose reduced the relative risk of CV events by 49% over 3.3 years versus placebo in patients with impaired glucose tolerance (2.2% vs 4.7%; P = 0.03) and by 35% over ≥1 year in patients with type 2 diabetes (9.4% vs 6.1%; P = 0.006). Conclusions: All components of the glucose triad (ie,FPG, HbA 1c, and PPG) should be considered in the management of type 2 diabetes. Therapy targeted at PPG has been shown to improve glucose control and to reduce the progression of atherosclerosis and CV events; therefore, physicians should consider monitoring and targeting PPG, as well as HbA lc and FPG, in patients with type 2 diabetes.