Abnormal ventilatory responses to hypoxia in Type 2 diabetes

• Published in: Diabetic medicine Vol. 22; no. 5; pp. 563 - 568
• Main Authors: Weisbrod, C. J., Eastwood, P. R., O'Driscoll, G., Green, D. J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.05.2005; Blackwell
• Subjects: Biological and medical sciences; breathing pattern; chemoreflex; diabetes; Diabetes Mellitus, Type 2 - complications; Diabetes Mellitus, Type 2 - physiopathology; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Female; Forced Expiratory Volume - physiology; Humans; Hypoxia - etiology; Hypoxia - physiopathology; Lung Volume Measurements; Male; Medical sciences; Middle Aged; minute ventilation; Respiration Disorders - etiology; Respiration Disorders - physiopathology; Endocrinopathy; Type 2 diabetes; breathing pattern; Oxygen; Metabolic diseases; Hypoxia; Ventilation; chemoreflex; diabetes; minute ventilation
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2005.01458.x

Aims  The incidence of Type 2 diabetes is increasing, along with its associated micro‐ and macrovascular disease manifestations. Previous studies indicate that patients with Type 2 diabetes exhibit abnormal cardiopulmonary reflex responses to various stimuli, although the impact of hypoxia, a common physiological stimulus, on ventilatory responses has not previously been studied in humans with Type 2 diabetes. Methods  Minute ventilation (V̇E) breathing pattern responses (total breath time, TTOT; expiratory time, TE; inspiratory time, TI; inspiratory duty cycle, TI/TTOT) were measured during 5 min each of normoxia and isocapnic hypoxia (arterial O2 saturation ∼85%) in eight subjects with Type 2 diabetes and seven age‐ and body mass index‐matched healthy subjects. Results  During normoxia, V̇E was similar in control and diabetic subjects (6.4 ± 1.2, 6.4 ± 1.1 l/min, respectively). In response to hypoxia, V̇E significantly increased in both groups (to 17.0 ± 5.0 and 9.5 ± 2.0 l/min, respectively, P < 0.05), but the magnitude of increase in V̇E was significantly less in diabetic than in control subjects (P < 0.05). In addition, the breathing pattern response to hypoxia differed between groups in terms of TI/TTOT and TTOT (P < 0.05), with control subjects significantly decreasing TTOT and TE (P < 0.05) while diabetic subjects tended to increase both. Conclusions  Relative to matched control subjects, Type 2 diabetic subjects exhibit blunted V̇E responses to acute isocapnic hypoxia, suggesting that this group of diabetic subjects possesses a chemoreflex ill‐equipped to respond homeostatically to hypoxic challenge.