We read with much interest the findings in the recent paper by West et al¹ of the prevalence of obstructive sleep apnoea (OSA) in men with type 2 diabetes. Although there may have been selection bias in the questionnaire respondents, the findings support the hypothesis that OSA is common in this population and is likely to be underdiagnosed. OSA is known to be independently associated with an increase in the cardiovascular risk factors that comprise the metabolic syndrome,² including diabetes mellitus and impaired glucose tolerance.³

We have reviewed our data on 156 successive patients with OSA recently diagnosed by polysolmnography, 114 of whom (72 men) had glucose measurements checked at the time of diagnosis. Sixteen patients (14%) were already known to have diabetes or impaired glucose tolerance. Although only five newly diagnosed cases of diabetes were identified, a further two had a single raised fasting glucose level and four had raised non-fasting glucose levels. Thus, a total of 11 patients (9.6%) were identified by the screening process as potentially having diabetes or impaired glucose tolerance.

Unsurprisingly, the patients with diabetes or impaired glucose tolerance had higher mean body mass indices (37 vs 33.2 kg/m²), but there seemed to be little difference in either the Epworth score (11.8 vs 9.9) or in the apnoea-hypopnoea index (22.6 vs 24.4). These data support active screening of patients with newly diagnosed OSA for diabetes in order to allow earlier recognition and treatment.