Oral Antidiabetic Agents Usually Drop A1C 1.5 Percent or Less
Sulfonylureas, thiazolidinediones most effective; benefit most apparent in first four to six months
MONDAY, Aug. 2 (HealthDay News) -- Oral antidiabetic (OAD) agents generally result in a maximum 1.5 percent drop in A1C levels, with sulfonylureas and thiazolidinediones having a slightly more beneficial effect than other classes of oral agents, according to research published in the August issue of Diabetes Care.
Diana Sherifali, R.N., of McMaster University in Hamilton, Canada, and colleagues conducted a systematic review and meta-analysis of 61 randomized controlled trials studying the effect of OAD agents on A1C levels. The analysis was conducted because previous reviews of the topic included studies of various designs and methodological approaches.
The reviewed trials included 15,760 participants randomized to an intervention OAD agent, and 10,607 randomized to placebo. The researchers found that thiazolidinediones and sulfonylureas lowered A1C levels by about 1.0 to 1.25 percent, while most OAD agents lowered them by 0.5 to 1.25 percent. Using meta-regression analysis, for each 1 percent higher the baseline pretreatment A1C level, a 0.5 greater decrease in A1C level was obtained after six months of treatment. The authors concluded that the benefit of an OAD agent was most apparent in the first four to six months of therapy, and that a 1.5 percent fall in A1C level was likely to be the maximum.
"This effect was fairly consistent between OAD classes with sulfonylureas and thiazolidinediones having the greatest reduction in [A1C]. The meta-regression analysis numerically demonstrated a small effect of baseline A1C on the fall of A1C with OAD treatment. Further carefully conducted OAD trials are needed to account for 1) combinations of OAD drug use and its impact on A1C levels; 2) the effectiveness of long-term OAD use on A1C levels; and 3) adverse and hypoglycemic events," the authors write.
The study was funded by an unrestricted grant from Merck Frosst. One of the authors received honoraria for providing advice or speaking to the manufacturers of various glucose-lowering agents, and his institution received funding for research from various pharmaceutical and medical device companies.