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Incidence and prevalence of type 1 diabetes mellitus in the PHARMO Data Network in the Netherlands

Incidence and prevalence of type 1 diabetes mellitus in the PHARMO Data Network in the Netherlands

Authors: Jelena Pavlović1, Louise Lemmens1, Jordy Gaspersz1, Marielle Vink2, Thomas Jans2, Mahtab Kaveh2, Bastiaan Van Den Berg2, Jetty A. Overbeek1

Affiliations: 1PHARMO Institute for Drug Outcomes Research, Lumanity, Utrecht, The Netherlands; 2Sanofi B.V., Amsterdam, The Netherlands.

Background:

Contemporary Dutch real-world data (RWD) on type 1 diabetes mellitus (T1D) epidemiology and acute presentation with diabetic ketoacidosis (DKA) is limited. Objectives were to estimate 2024 crude, age- and sex-standardized T1D incidence and prevalence, and proportion of incident DKA requiring hospitalization in the Netherlands.

Methods:

This retrospective study used routinely collected general practitioner (GP) and hospital data from the PHARMO Data Network from 2003 to 2024. T1D was identified with GP and hospital diagnostic codes, or first observed insulin use before 30 years. Age- and sex-standardized incidence and prevalence rates per 100,000 persons were calculated by direct standardization to the 2024 Dutch general population. Incident DKA requiring hospitalization in 2024 was based on the hospital admissions and described using cumulative proportions.

Results:

Among 2,838,664 individuals with linked GP and hospital data in 2024, 296 incident and 15,794 prevalent T1D cases were identified. Crude 2024 T1D incidence was 13.7 per 100,000 (95%CI:12.1-15.3). Age- and sex-standardized incidence was 14.1 per 100,000 (95%CI:12.5-15.8): 13.1 per 100,000 (95%CI:11.0-15.4) and 15.1 per

100,000 (95%CI:12.8-17.7) males and females, respectively. Crude 2024 T1D prevalence was 556.4 per 100,000 (95%CI: 547.7-565.1). Age- and sex-standardized prevalence was 565.3 per 100,000 (95%CI:556.5-574.2): 575.0 per 100,000 (95%CI:562.5-587.8) and 555.8 per 100,000 (95%CI:543.4-568.3) for males and

females, respectively. Among 296 incident T1D cases, 7.5% (95%CI:5.0-11.1) experienced DKA requiring hospitalization, occurring almost exclusively at the time of T1D diagnosis (19 of 22 cases).

Discussion/Conclusions:

2024 Dutch incidence and prevalence estimates were consistent with recent national estimates. DKA requiring hospitalization was the first presentation of T1D in 11% of pediatric population (0-14 years). DKA proportions were likely underestimated because emergency department data were unavailable; many first-presentation DKA in T1D cases may be managed in the emergency departments without requiring hospitalization and therefore would not be captured in hospital data, leading to DKA under-ascertainment.