Factors Associated with Long-Term Oral Hypoglycemic Agent Responsiveness in Korean Patients with Type 2 Diabetes Mellitus

BACKGROUND: This study was performed to determine the factors associated with long-term oral hypoglycemic agent (OHA) responsiveness in Korean type 2 diabetic patients. METHODS: Two groups of patients were selected among the type 2 diabetic patients who were followed for more than two years at a university hospital diabetes clinic. The OHA responsive group consisted of 197 patients whose HbA1c levels were maintained at ≤7% with OHA for more than two years. The OHA failure group consisted of 180 patients whose HbA1c levels were >8% in spite of optimal combined OHA therapy or patients who required insulin therapy within the two years of the study. RESULTS: The OHA failure group had higher baseline values of fasting and postprandial glucose, HbA1c, and lower fasting, postprandial, and delta C-peptide compared to those of the OHA responsive group. The OHA failure group also had a higher proportion of female patients, longer diabetic duration, and more family history of diabetes. There were no significant differences in body mass index (BMI) or insulin resistance index between the two groups. Multiple logistic regression analysis showed that the highest quartile of baseline fasting, postprandial glucose, and HbA1c and the lowest quartile of postprandial and delta C-peptide were associated with an increased odds ratio of OHA failure after adjustment for age, sex, body mass index, and family history of diabetes. CONCLUSION: Lower baseline values of postprandial and delta C-peptide and elevated fasting glucose and HbA1c are associated with long-term OHA responsiveness in Korean patients with type 2 diabetes mellitus.