In the United Kingdom (UK), about 1.5 million individuals have learning disabilities. This makes them more vulnerable to chronic conditions like type 2 diabetes mellitus (T2DM). This population has a lower life expectancy due to a combination of lifestyle factors, genetic predisposition, and socioeconomic challenges. Management of T2DM is particularly difficult for these individuals as it requires consistent self-care behaviors such as medication adherence, regular blood glucose monitoring, physical activity, and dietary control. Cognitive impairments and communication problems further complicate these essential tasks.
This study aimed to investigate the difference in glycemic control, initiation of insulin therapy, progression to diabetes-related complications, and mortality between individuals with T2DM who have a learning disability and those without.
This observational cohort study was conducted using the UK Clinical Practice Research Datalink (CPRD) GOLD database. It contains anonymized primary care electronic health records linked to the Office for National Statistics (ONS) mortality data and the Index of Multiple Deprivation (IMD). Adults aged 18 years and older with a new diagnosis of T2DM from January 2004 to January 2021 were included. Exclusion criteria included individuals with less than 6 months of follow-up, insulin prescription within 12 months before or 2 years after diagnosis (to avoid misclassification of type 1 diabetes), and diagnosis within 6 months of registering at a practice (to minimize the inclusion of pre-existing cases).
The primary exposure of interest was a diagnosis of learning disability recorded before the T2DM diagnosis. Outcomes assessed included glycated hemoglobin (HbA1c) levels at 2- and 5-year post-diagnosis, initiation of insulin therapy beyond 2 years (as a proxy for severe diabetes), incidence of macrovascular and microvascular complications occurring more than 6 months after diagnosis, and all-cause as well as diabetes-related mortality.
Of 3,52,215 individuals diagnosed with T2DM during the study period, 2,80,300 met the inclusion criteria. About 2,074 (0.74%) had a recorded learning disability. Compared with those without learning disabilities, affected individuals were younger at baseline (mean age: 51 versus 64 years), had shorter follow-up (5.3 versus 6.0 years), and were more likely to be male, of White ethnicity, severely obese, and residing in more deprived areas. At baseline, they presented with higher HbA1c, lower systolic blood pressure, greater use of antihypertensive and lipid-lowering medication, and higher rates of diabetes-related complications.
In terms of glycemic control, after adjusting for confounders, individuals with learning disabilities demonstrated slightly but consistently lower mean HbA1c at both two years (−0.05%, 95% confidence interval [CI]: −0.07 to −0.02, p<0.001) and five years (−0.05%, 95% CI: −0.08 to −0.02, p=0.004) post-diagnosis. They also had lower odds of poor glycemic control at both time points with odds ratios of 0.82 (95% CI: 0.73 to 0.92, p=0.001) at two years and 0.81 (95% CI: 0.70 to 0.94, p=0.004) at five years. For insulin initiation, there was weak evidence of earlier initiation among those with learning disabilities (hazard ratio [HR]: 1.20, 95% CI: 1.00 to 1.45, p=0.052), though this association was attenuated after adjustment for baseline HbA1c (HR: 1.04, 95% CI: 0.81 to 1.34, p=0.767). No significant associations were observed for microvascular complications (HR: 1.09, 95% CI: 0.96 to 1.23, p=0.190) or macrovascular complications (HR: 1.13, 95% CI: 0.89 to 1.44, p=0.308). In the ONS-linked subgroup, which represented 43% of the cohort, learning disability was associated with nearly 2-fold increased risk of both all-cause mortality (HR: 1.81, 95% CI: 1.60 to 2.04, p<0.001) and diabetes-related mortality (HR: 2.01, 95% CI: 1.43 to 2.84, p<0.001).
In conclusion, this study found that individuals with learning disabilities achieved better glycemic control but were more likely to initiate insulin treatment and faced substantially higher risks of all-cause and diabetes-related mortality. Missing results could have introduced bias in the glycemic control estimates and potential exposure misclassification. Further research is required to understand and address the healthcare barriers for this vulnerable population.
References: Wing A, Mathur R. The impact of learning disabilities on control, management, and outcomes of type 2 diabetes mellitus in the UK: an observational cohort study using the Clinical Practice Research Datalink. BMJ Open Diabetes Res Care. 2025;13(1):e004879. doi:10.1136/bmjdrc-2024-004879
