Adherence and Persistence to Basal Insulin Among People with Type 2 Diabetes in Europe: A Systematic Literature Review and Meta-analysis

IntroductionDiabetes is associated with a number of complications, particularly if glycaemic targets are not achieved. Glycaemic control is highly linked to treatment persistence and adherence. To understand the burden of poor persistence and adherence, this systematic literature review identified existing evidence regarding basal insulin adherence/non-adherence and persistence/non-persistence among people with diabetes in Western Europe (defined as the UK, France, Spain, Switzerland, the Netherlands, Ireland, Austria, Portugal, Denmark, Norway, Sweden, Finland, Italy, Germany, Iceland and Belgium).MethodsEligible studies were systematically identified from two databases, Medline and Embase (published between 2012 and June 2022). Conference abstracts from ISPOR and EASD were manually included. Identified studies were screened by two independent reviewers in a two-step blinded process. The eligibility of studies was decided on the basis of pre-established criteria. A proportional meta-analysis and comparative narrative analyses were conducted to analyse the included studies.ResultsTwelve studies were identified. Proportions of adherence/non-adherence and persistence/non-persistence varied across studies. Pooled rates of non-persistence at 6, 12 and 18 months were 20.3% (95% CI 13.8; 27.8), 33.8% (95% CI 24.1; 44.3) and 36.5% (95% CI 33.6; 39.4), respectively. In the literature, the proportion of adherent people ranged from 41% to 64% (using the outcome measure medication possession ratio (MPR) > 80%), with a pooled rate of 55.6% (95% CI 45.3; 65.6), suggesting that approximately 44% of people with type 2 diabetes (T2D) are non-adherent.ConclusionThe results highlight that almost half of patients with T2D in Western Europe have poor adherence to insulin therapy and, at 18 months, one in three patients do not persist on treatment. These findings call for new basal insulin therapies and diabetes management strategies that can improve treatment persistence and adherence among people with T2D.