Clinical significance of targeting postprandial and fasting hyperglycemia in managing type 2 diabetes mellitus.

Measurement of glycosylated hemoglobin (HbA1c) remains the gold standard for the assessment of glycemic control in patients with type 2 diabetes. Recent investigations have studied the correlations between HbA1c levels and other aspects of glucose metabolism, specifically, postprandial glucose (PPG) and fasting plasma glucose (FPG). The results suggest that PPG is also important to overall glycemic control and may be a better index of glucose regulation than FPG. Further, elevated PPG values have been associated with cardiovascular complications and cardiovascular mortality. Such evidence has led to recommendations that PPG levels be monitored as part of type 2 diabetes management, in addition to HbA1c and FPG. These glycemic parameters are differentially affected by the various classes of oral antidiabetic agents used in the treatment of type 2 diabetes--sulfonylureas, meglitinides, insulin sensitizers and alpha-glucosidase inhibitors. The sulfonylureas, for example, lower HbA1c, PPG and FPG, while the meglitinides have virtually no effect on FPG. The insulin sensitizer metformin, on the other hand, does not affect PPG levels, whereas the alpha-glucosidase inhibitors, in the presence of a high-carbohydrate diet, can effectively lower PPG. Many patients receive combination therapy, thereby benefiting from multiple mechanisms of glucose control, although in most cases insulin must later be added to the regimen in order to effectively suppress FPG. Thus, all aspects of glucose metabolism appear to be clinically relevant and should be monitored for effective diabetes management. Further study will more precisely define the clinical significance of PPG.