Changes in diabetes medications in the Diabetes and Periodontal Therapy Trial and their effect on hemoglobin A1c (HbA_1c)

Objective Evaluate the effect of medications and medication changes during the Diabetes and Periodontal Therapy Trial (DPTT) on the primary study outcome, namely, change in hemoglobin A1c (HbA_1c) at 6 months following baseline. Methods The DPTT set strict criteria for changes in diabetes medications. Medication change was defined as: change in dose of any 1 oral hypoglycemic agent by more than two-fold, change in dose of insulin of > 10% and/or addition or subtraction of an oral hypoglycemic agent, insulin or non-insulin injectable agents. Comparisons between the treatment (non- surgical periodontal therapy) and control (no therapy) groups used t-tests for continuous variables and chi-square tests for categorical variables, including DPTT defined diabetes medication changes between baseline (BL) and 3 month visits and 3- and 6-month visits. Changes in HbA_1c were compared across the four medication change categories using ANOVA models, overall and for each treatment group separately. Results Baseline medication use was similar between the treatment groups (p > 0.40), as were medication changes between BL- 3 month visits and 3 and 6 month visits (p = 0.58). Participants with higher BL HbA_1c (> 8%) and those taking insulin at BL were more likely to have a change in medication (p = 0.03). Conclusions The DPTT had the most rigorous definition of medication changes and medication monitoring of any trial in this field to date. The absence of a significant difference in medication changes between treatment groups may suggest that such changes did not play a role in the negative outcome of the DPTT.