Stability of commonly used sleep questionnaires in people with type 2 diabetes mellitus treated in primary care.

Abstract

Sleep is increasingly recognized as a modifiable factor influencing metabolic and cardiovascular outcomes in type 2 diabetes mellitus (T2DM). Reliable sleep assessments are essential in primary care to assess sleep in T2DM. However, the stability of self-rated sleep measures in this group remains unclear. This study evaluated the temporal stability of the Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and STOP-BANG questionnaire in T2DM patients. This prospective observational study included 53 individuals with T2DM referred from Swedish primary care for OSA evaluation (median age 65, 53% male). A total of 109 eligible individuals were approached and 53 agreed to participate. Participants completed ESS, PSQI, and STOP-BANG twice with a median interval of 68.5 days. Stability was analysed using Spearman's rho, intraclass correlation coefficients (ICC), and Cohen's kappa. Systematic differences were assessed with the Wilcoxon signed-rank test, and the impact of interval duration on score stability was analysed using robust rank regression. ESS, PSQI, and STOP-BANG all showed significant test-retest stability. Spearman's rho was 0.73 for ESS, 0.78 for PSQI, and 0.81 for STOP-BANG (all p < 0.001), and Cohen's kappa at clinical thresholds was 0.62, 0.46, and 0.75, respectively. No systematic score drift was observed for ESS or PSQI; STOP-BANG exhibited a small mean decrease (-0.4 points, p < 0.01). No significant association was found between interval length and score differences. This study confirms the stability of ESS and PSQI in assessing sleep quality and sleepiness in patients with T2DM. STOP-BANG showed reasonable stability, with variations in snoring responses suggesting it may be more effective if administered prior to the clinical visit. Incorporating these validated tools into routine care could improve the management of sleep disturbances and their impact on metabolic health.