The burden of treatment failure in type 2 diabetes

Abstract

OBJECTIVE - In type 2 diabetes, therapies to maintain blood glucose control usually fail after several years. We estimated the glycemic burden that accumulates from treatment failure and describe the time course and predictors of failure. RESEARCH DESIGN AND METHODS - A prospective, population-based study using retrospective observational data. We identified all 7,208 complete courses of treatment with nondrug therapy, sulfonylurea monotherapy, metformin monotherapy, and combination oral antihyperglycemic therapy between 1994 and 2002, inclusive, among members of the Kaiser Permanente Northwest Region. We calculated mean cumulative glycemic burden, defined as HbA1c-months >8.0 or 7.0% for each treatment. We then measured the likelihood that the next HbA1c would exceed 8.0 and 7.0% after HbA1c exceeded each of ten hypothetical treatment thresholds. Finally, we estimated multivariate logistic regression models to predict when HbA1c would continue to deteriorate. RESULTS - In this well-controlled population, the average patient accumulated nearly 5 HbA1c-years of excess glycemic burden >8.0% from diagnosis until starting insulin and about 10 HbA 1c-years of burden >7.0%. Whenever patients crossed the American Diabetes Association-recommended treatment threshold of 8.0%, their next HbA1c result was as likely to be <8.0 as >8.0%. Multivariate prediction models had highly statistically significant coefficients, but predicted <10% of the variation in future HbA1c results. CONCLUSIONS - Clinicians should change glucose-lowering treatments in type 2 diabetes much sooner or use treatments that are less likely to fail. An action point at 7.0% or lower is more likely to prevent additional deterioration than the traditional action point of 8.0%.