In this nationwide NZ birth cohort study, type 1 diabetes was associated with significantly lower educational outcomes of high school attainment, high school attendance and university enrolment. Educational outcomes were particularly affected among those with type 1 diabetes who, post diagnosis, underwent a hospitalisation for DKA or hypoglycaemia. Among Māori, those with type 1 diabetes experienced significantly lower rates of NCEA Level 3 attainment, whereas, among Pacific peoples, those with type 1 diabetes had significantly lower rates of any NCEA qualification. In the context of conflicting findings in existing literature, the present study further elucidates the relationship between type 1 diabetes and educational outcomes using contemporary data at the population level and exploring outcomes at multiple points in the education system.

The finding that type 1 diabetes is associated with lower educational attainment is consistent with several nationwide studies [14,15,16,17] but is in contrast to others [9, 13]. Differences in findings might be due to selection bias. For example, unlike a number of studies with null findings, the present study, and that of Lindkvist et al [17], did not exclude unenrolled students or those in specialist schools [9, 13, 17, 21]. This suggests that such exclusions may mask the impact of type 1 diabetes. Further variability in findings may also be attributable to differences in outcome measurement. In NZ, the NCEA is internally and externally assessed across the year. It is possible that students with type 1 diabetes who experience higher levels of school absence may find achieving internally assessed qualifications (which are often completed over time) particularly difficult. Given that other studies have typically explored outcomes derived from one-off assessments, this may help to explain the negative effect of type 1 diabetes observed in the present study [9, 21, 44]. Cross-country variation in the level and quality of both health support and education support for young people with type 1 diabetes, including variability in the time periods covered and advances in diabetes treatment, may also have influenced the results.

Our results indicating that type 1 diabetes is associated with school absenteeism align with previous research [10,11,12,13]. They are also consistent with the lower subsequent educational outcomes observed among the type 1 diabetes group, as school attendance is strongly associated with academic attainment [45]. Similarly, the negative association between type 1 diabetes and university enrolment, as found by Lindkvist et al [17], is also consistent with what one would expect, given lower school attainment levels among the type 1 diabetes group. These findings are concerning given the strong association between university qualifications and later income in NZ [46], and the known link between poor educational outcomes and deleterious consequences in later life such as increased risk of unemployment and crime [47].

The finding that post-diagnosis hospitalisation for DKA or hypoglycaemia was a significant predictor of lower educational outcomes among those with type 1 diabetes is in line with a number of existing studies [9, 11, 17]. Children hospitalised for DKA or hypoglycaemia will generally have less healthy glucose levels, will require more diabetes treatment and will experience a greater psychosocial burden. They may also be from households with fewer resources available, which impacts both health and educational outcomes. Diabetes and glucose variability substantially impact the childhood brain [48,49,50]. Compounding this effect are the known psychosocial disruptions of childhood diabetes [51,52,53]. Taken in the context of the now multiple diabetes registry studies highlighting that the majority of children are still not meeting recommended glucose targets [54,55,56], this study provides a further call to arms for ongoing efforts to continue to improve glucose levels using all proven methods available. Such efforts include improved access and equity to continuous glucose monitoring [57], automated insulin delivery [58] and diabetes psychosocial support, education and nutrition.

As a collective, Māori and Pacific children already experience inequitable educational outcomes compared with non-Māori/non-Pacific children [27, 59]. The findings of this study suggest that, for several educational outcomes, Māori and Pacific peoples with type 1 diabetes are achieving at similar levels to their peers without type 1 diabetes. However, for other outcomes, they indicate that the additional complexity of type 1 diabetes creates multiple disadvantages, widening existing disparities further. This highlights the need for diabetes-related support for students who already face inequitable access to the determinants of health, including the provision of culturally competent and appropriate health and education services [60].

Our findings point to the need for policymakers, school leaders and teachers to be mindful of students’ needs and potential impacts of chronic illness on their access to curriculum content, particularly in relation to high-stakes school leaver assessments. Proactive measures with adequate resourcing to support student achievement and success, including embedding and sustaining a whole-school approach to the promotion of student wellbeing, are required. Initiatives to improve educational outcomes for those with type 1 diabetes are underway in other countries, for example the Diabetes in Schools Program in Australia [61]. However, because they have only recently been implemented, their impact on educational and health outcomes is unknown.

This study has a number of strengths. It included a large, contemporary, national sample allowing identification of a sizeable group of individuals with type 1 diabetes and enabling analysis of subpopulations including Māori and Pacific peoples, those with early-onset type 1 diabetes and those with a previous hospitalisation for DKA or hypoglycaemia. The data enabled examination of aspects of the pathway through education from high school to university-level study, and adjustment for a range of socioeconomic and maternal measures known to associate with educational outcomes. The study design also accounted for early exit as a result of death or long-term overseas travel.

The study must also be viewed in light of several limitations. The educational attainment outcomes are blunt and do not enable analysis of which areas of learning (e.g. numeracy and literacy) are most affected. Attendance data were available only for term 2 and may not be representative of the full school calendar year. While we included controls for a number of important covariates, other measures associated with educational outcomes such as congenital anomalies, birthweight, gestational age and Apgar score were unable to be accounted for. Moreover, while we excluded, in a sensitivity analysis, students who attended specialist schools, the available data did not allow us to exclude students with special educational needs within the mainstream setting. The impact of omitted variables on study findings is unknown. The VDR is not a formal registry of people with diabetes in NZ; instead, it identifies people who have diabetes by drawing on health service use from multiple datasets. While the VDR is validated and has strong predictive properties (e.g. high sensitivity and specificity), misclassification error may have impacted the study findings [33]. Moreover, the VDR does not readily distinguish between type 1 and type 2 diabetes. However, type 2 diabetes is relatively uncommon in young children (aged <13 years), and those with a type 2 diabetes diagnosis recorded in hospital data were excluded [34]. The data employed in this study do not include measures of HbA1c, which would have been an additional important marker of glucose levels compared with hospitalisations with DKA or hypoglycaemia, which is a less nuanced measure. Lastly, the birth cohort were born mostly in the 1990s and treatment has changed subsequently; however, because of the follow-up time required to observe educational outcomes, the present study was unable to account for newer developments in therapy.

Given the inconsistency of the findings in the existing literature, research to better understand the drivers of educational success among those with type 1 diabetes should be prioritised. Among other things, this might include improving the ability of school systems to accommodate chronic illnesses such as type 1 diabetes, and understanding their potential impacts on learning as well as the intersectionality of inequitable access to the social determinants of health and type 1 diabetes. Using temporal data available in the IDI, and more nuanced educational data such as subject-specific attainment information, may help to better elucidate the relationship between type 1 diabetes and educational outcomes. Moreover, further research might also explore other medium- and long-term impacts of type 1 diabetes, such as impacts on employment, income and other forms of continued education. Analysis of the influence of post-pubertal and teenage diagnoses of type 1 diabetes on educational outcomes, because of the substantial psychosocial impacts, also warrants further investigation. Analysis by sex/gender may also provide further insights into the relationship between educational success and type 1 diabetes.

In this whole NZ cohort study, negative associations between type 1 diabetes and educational outcomes, particularly in those with surrogate markers of glycaemic variability, highlight a further aspect of the profound impact of diabetes on the developing brain and psychosocial development. Ongoing efforts are needed to ensure barrier-free access to education for young people with type 1 diabetes, including school-based supports to enable student achievement and success and equitable outcomes for indigenous populations.