COMBINSI (COMBat to INSufficient Insulin therapy) - A Portuguese project in type 2 diabetes

Inadequate glycemic control in type 2 diabetes (T2D) increases the risk of diabetes-related complications. Insulin initiation is often delayed for several years. This study aims to estimate the adequacy of insulin therapy prescription to people living with T2D in a primary care setting.

This was a cross-sectional study based on adults with T2D in a Portuguese local health unit between January 2019 and January 2020. Subjects under insulin therapy were compared with non-insulin-treated subjects with Hemoglobin A1c (HbA1c) ≥9% regarding clinical and demographic characteristics. The proportion of insulin-treated subjects in both of these groups was defined as insulin therapy index.

Our study included 13,869 adults living with T2D, among whom 11.5% were treated with insulin therapy and 4.1% had HbA1c ≥ 9% and were not under insulin therapy. Insulin therapy index was 73.9%. When comparing with non-insulin-treated subjects with HbA1c ≥ 9%, insulin-treated subjects were significantly older (75.8 vs 66.2 years p < 0.001), had lower HbA1c (8.3 vs 10.3% p < 0.001), lower estimated glomerular filtration rate (66.4 vs 74.0 ml/min/1.73 m²p < 0.001), lower LDL-cholesterol (87.1 vs 105.8 mg/dl), and higher rates of atherosclerotic cardiovascular disease (32.7 vs 16.7% p < 0.001).

Insulin therapy is underprescribed in T2D, with over 1-in-4 people living with T2D not being prescribed insulin despite deficient glycemic control. These findings highlight the need for insulin therapy when glycemic control is inadequate under other interventions.