Treatment pattern trends of medications for type 2 diabetes in British Columbia, Canada

Abstract

Introduction: Several new oral drug classes for type 2 diabetes (T2DM) have been introduced in the last 20 years accompanied by developments in clinical evidence and guidelines. The uptake of new therapies and contemporary use of blood glucose-lowering drugs has not been closely examined in Canada. The objective of this project was to describe these treatment patterns and relate them to changes in provincial practice guidelines.

Research design and methods: We conducted a longitudinal drug utilization study among persons with T2DM aged ≥18 years from 2001 to 2020 in British Columbia (BC), Canada. We used dispensing data from community pharmacies with linkable physician billing and hospital admission records. Laboratory results were available from 2011 onwards. We identified incident users of blood glucose-lowering drugs, then determined sequence patterns of medications dispensed, with stratification by age group, and subgroup analysis for patients with a history of cardiovascular disease.

Results: Among a cohort of 362 391 patients (mean age 57.7 years old, 53.5% male) treated for non-insulin-dependent diabetes, the proportion who received metformin monotherapy as first-line treatment reached a maximum of 90% in 2009, decreasing to 73% in 2020. The proportion of patients starting two-drug combinations nearly doubled from 3.3% to 6.4%. Sulfonylureas were the preferred class of second-line agents over the course of the study period. In 2020, sodium-glucose cotransporter type 2 inhibitors and glucagon-like peptide-1 receptor agonists accounted for 21% and 10% of second-line prescribing, respectively. For patients with baseline glycated hemoglobin (A1C) results prior to initiating diabetic treatment, 41% had a value ≤7.0% and 27% had a value over 8.5%.

Conclusions: Oral diabetic medication patterns have changed significantly over the last 20 years in BC, primarily in terms of medications used as second-line therapy. Over 40% of patients with available laboratory results initiated T2DM treatment with an A1C value ≤7.0%, with the average A1C value trending lower over the last decade.

Keywords: diabetes mellitus, type 2; drug utilization; health services research; practice guideline.

Figure 1

Study flow chart. MSP, Medical Service Plan.

Figure 2

Glycated hemoglobin value immediately preceding treatment initiation.

Figure 3

First-line therapy by period of cohort entry. AGI, alpha-glucosidase inhibitor; DPP4, dipeptidyl peptidase-4; GLP1, glucagon-like peptide-1 receptor; Ins, insulin; Meg, meglitinide; Met, metformin; SGLT2, sodium-glucose cotransporter type 2; SU, sulfonylurea; TZD, thiazolidinedione.

Figure 4

Annual proportion of incident users of blood glucose-lowering drugs. GLP1, glucagon-like peptide-1 receptor; SGLT2, sodium-glucose cotransporter type 2.

Figure 5

Second-line prescribing of blood glucose-lowering drugs post-metformin monotherapy. DPP4, dipeptidyl peptidase-4; GLP1, glucagon-like peptide-1 receptor; SGLT2, sodium-glucose cotransporter type 2.

Figure 6

Path of therapy: blood glucose-lowering drug use by cohort entry period. T2DM, type 2 diabetes mellitus.