Diabetic polyneuropathy is associated with respiratory muscle impairment in type 2 diabetes

Diabetes has a major negative effect on intensive care unit outcome. This has been partly attributed to impaired respiratory neuromuscular function. However, data on respiratory neuromuscular involvement in diabetes are lacking. This study therefore aimed to assess respiratory neuromuscular function related to diabetic polyneuropathy in patients with type 2 diabetes.

Both volitionally assessed maximal inspiratory and expiratory mouth pressures, and sniff nasal and transdiaphragmatic pressures were comparable between diabetic patients and controls (p > 0.1 for all). TwPmo was reduced in diabetic patients compared with controls (1.3 ± 0.5 vs 1.0 ± 0.4 kPa; p = 0.04), while TwPdi was comparable (1.7 ± 0.5 vs 1.6 ± 0.7 kPa; p = 0.6). Following subgroup analysis, patients with no or mild polyneuropathy (n = 10) as assessed by neurological disability scoring had normal respiratory neuromuscular function, whereas patients with moderate or severe polyneuropathy (n = 11) presented with markedly impaired respiratory neuromuscular function as indicated by TwPmo (1.3 ± 0.4 vs 0.8 ± 0.3 kPa; p = 0.01) and TwPdi (1.9 ± 0.6 vs 1.1 ± 0.4 kPa; p < 0.01).

With regard to volitional tests, diabetes does not affect respiratory neuromuscular function. In contrast, the application of non-volitional phrenic nerve stimulation provides strong evidence that diabetic polyneuropathy, as simply assessed by neurological disability scoring, is associated with substantially impaired respiratory neuromuscular function in type 2 diabetic patients.