Changes in subjective sleep quality in patients with type 2 diabetes who did not use Sleep agents: a cross-sectional study according to age and clinical background

Aim Diabetes and aging are both well-established risk factors for insomnia. Therefore, we investigated the changes in subjective sleep quality in relation to clinical backgrounds and age in patients with type 2 diabetes mellitus (T2DM). Methods This cross-sectional study included 380 participants with T2DM who were between 18 and 79 years of age from our outpatient clinics. Individuals with any symptoms and medical histories associated with obstructive sleep apnea (OSA) were excluded from the interview and analyses. Data were collected using self-administered questionnaires, namely the Pittsburgh Sleep Quality Index (PSQI) and the Morning-Evening Questionnaire (MEQ), as well as medical records and blood samples. We performed stratified analyses according to age decades. Results The number of patients in the age groups (in years) was as follows: < 50 ( n = 69), 50–60 ( n = 52), 60–70 ( n = 138), and 70–80 ( n = 121). PSQI score was highest in the < 50 group (4.99 ± 2.40), and significantly decreased with age ( p < 0.05). Body mass index (BMI) was also highest in the < 50 group (25.5 ± 4.8 kg/m 2 ), and markedly decreased with age ( p < 0.01). Interestingly, BMI was significantly correlated with the PSQI score (rs = 0.157, p < 0.05). We also found that younger patients had shorter sleep duration, stronger daytime sleepiness, and a tendency for the evening type. Conclusion Younger T2DM patients had poorer sleep quality and higher BMI. Our findings suggest that insomnia should be accounted for as a potential comorbidity when examining or treating patients with T2DM and obesity even in the younger population.