Aims. The aim of this study was to investigate the impact of new insights and revised guidelines on initial and follow-up treatment with antihyperglycaemic drugs over the period 1998-2003.
Methods. The InterAction Database (IADB), which contains pharmacy dispensing data from 53 community pharmacies in the Northern and Eastern part of the Netherlands, was used in this study. Prevalence and incidence rates of oral antihyperglycaemic drug use were calculated for each year. Follow-up treatment was compared for two cohorts of initial users of oral antihyperglycaemic drugs, starting treatment either 1 year before or 1 year after guideline revision.
Results. The prevalence and incidence rate of oral antihyperglycaemic drug use increased over the study period from 1.8% to 2.4% (P <0.001) and 0.3% to 0.4% (P = 0.04). The proportion of metformin as initial treatment increased rapidly in the observation period from 14% to 50% (P <0.001). Initial users of metformin in 2000 received additional treatment with a sulphonylurea in the follow-up period less often compared with those who started metformin in 1998 (46% vs. 60%, P <0.004). In contrast, initial users of sulphonylurea in 2000 received additional treatment with metformin more often compared with those who started a sulphonylurea in 1998 (42% vs. 36%, P <0.008). The new drugs, thiazolidinediones and meglitinides, were seldom used as initial treatment
Conclusions. New insights and the revision of the practice guideline were followed by a significant increase in both initial and follow-up treatment with metformin among patients with Type 2 diabetes mellitus.