Sociodemographic disparities in non-diabetic hyperglycaemia and the transition to type 2 diabetes: evidence from the English Longitudinal Study of Ageing

Aim To explore whether there are social inequalities in non-diabetic hyperglycaemia (NDH) and in transitions to type 2 diabetes mellitus and NDH low-risk status in England. Methods Some 9143 men and women aged over 50 years were analysed from waves 2, 4, 6 and 8 (2004-2016) of the English Longitudinal Study of Ageing (ELSA). Participants were categorized as: NDH 'low-risk' [HbA(1c)< 42 mmol/mol (< 6.0%)], NDH [HbA(1c)42-47 mmol/mol (6.0-6.4%)] and type 2 diabetes [HbA(1c)> 47 mmol/mol (> 6.4%)]. Logistic regression models estimated the association between sociodemographic characteristics and NDH, and the transitions from NDH to diagnosed or undiagnosed type 2 diabetes and low-risk status in future waves. Results NDH was more prevalent in older participants, those reporting a disability, those living in deprived areas and in more disadvantaged social classes. Older participants with NDH were less likely to progress to undiagnosed type 2 diabetes [odds ratio (OR) 0.27, 95% confidence interval (CI) 0.08, 0.96]. NDH individuals with limiting long-standing illness (OR 1.72, 95% CI 1.16, 2.53), who were economically inactive (OR 1.60, 95% CI 1.02, 2.51) or from disadvantaged social classes (OR 1.63, 95% CI 1.02, 2.61) were more likely to progress to type 2 diabetes. Socially disadvantaged individuals were less likely (OR 0.64, 95% CI 0.41, 0.98) to progress to NDH low-risk status. Conclusions There were socio-economic differences in NDH prevalence, transition to type 2 diabetes and transition to NDH low-risk status. Disparities in transitions included the greater likelihood of disadvantaged social groups with NDH developing type 2 diabetes and greater likelihood of advantaged social groups with NDH becoming low-risk. These socio-economic differences should be taken into account when targeting prevention initiatives.