Sleep-disordered breathing in nonobese diabetic subjects with autonomic neuropathy

To assess the occurrence and nature of sleep-disordered breathing (SDB) in 26 adult, nonobese diabetics (18 with autonomic neuropathy (DAN+) (age 45 (41–50) yrs; body mass index (BMI) 24.1 (22–26) kg·m −2 ) and eight without autonomic neuropathy (DAN−) (age 45 (35–55) yrs; BMI 24.8 (23–26) kg·m −2 )) overnight full sleep studies and measurements of central and peripheral carbon dioxide (CO 2 ) chemosensitivity were performed. DAN+ were divided in two subgroups, according to the presence (DAN+PH+; n=10) or absence (DAN+PH−; n=8) of postural hypotension. Ten normal subjects were studied as controls (age 42 (36–48) yrs; BMI 24.4 (23–25) kg·m −2 ). In contrast to DAN− and controls, who did not show SDB, five DAN+ (four DAN+PH− and one DAN+PH+) had an apnoea/hypopnoea index ≥10 and four DAN+ (two DAN+PH− and two DAN+PH+) had an apnoea index ≥5. All the events were obstructive, occurring mainly during rapid eye movement (REM) sleep. Ten DAN+ exhibited a mean lowest oxygen saturation 2 . Both DAN+ subgroups showed a marked reduction in peripheral CO 2 chemosensitivity. In conclusion, adult nonobese diabetics with autonomic neuropathy, independent of the severity of their dysautonomy, have obstructive sleep apnoea/hypopnoea with a frequency >30%. A decrease in peripheral carbon dioxide chemosensitivity prevents adult nonobese diabetics with autonomic neuropathy and postural hypotension from experiencing posthyperventilatory central sleep apnoea, despite an increased hypercapnic central drive.