It remains unclear, whether exercise training as part of lifestyle intervention has favorable effects on the development or progression of diabetic neuropathy in patients with type 2 diabetes (T2D). Therefore, we assessed peripheral and autonomic nerve fiber function and morphology in patients with T2D as well as in individuals with normal glucose tolerance (CON) before and after a high intensity interval training (HIIT) intervention program over 12 weeks. The T2D group included 20 male individuals ([median (1st; 3rd quartile)] age: 56 (53; 63) years; diabetes duration: 5 (2; 9) years; BMI: 31.2 (28.6; 32.8) kg/m²; HbA1c: 6.9 (6.4; 8.0)%). The CON group was matched for age, sex, and BMI (n=23; age: 57 (53; 60) years; BMI: 30.3 (28.4; 32.2) kg/m²; HbA1c: 5.4 (5.2; 5.7)). Somatosensory and autonomic nerve tests included nerve conduction velocity, quantitative sensory testing, skin biopsy, corneal confocal microscopy, cardiovascular autonomic function tests (CAFT), and spontaneous baroreflex sensitivity (BRS). After 12 weeks of HIIT, no improvement in somatosensory nerve tests was detected in T2D or CON. In both groups, resting heart rate decreased ([mean±SEM] baseline vs. follow-up: T2D: 68.8±2.3 vs. 63.4±1.8 bpm; CON: 65.1±1.8 vs. 60.2±1.9 bpm; both P<0.05). The change in systolic blood pressure after standing up (-13.9±2.6 vs. -9.4±2.2 mmHg) and three BRS sequence analysis indices (e.g., BRS-slope: 7.9±1.9 vs. 12.6±5.1 ms/mmHg) improved in T2D (P<0.05), while the standard deviation of normal RR intervals (SDNN; 36.1±2.6 vs. 55.3±8.8 ms; P<0.05) and coefficient of variation (CV; 3.8±0.3 vs. 5.2±0.7%; P<0.05) improved in CON.

In conclusion, while cardiovascular autonomic function improved moderately after 12 weeks of HIIT in male T2D patients, a longer training period may be required to achieve favorable effects on somatosensory nerve function or morphology.

Disclosure

G.J. Bönhof: None. A. Strom: None. M. Apostolopoulou: None. D. Pesta: None. M. Roden: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Poxel SA, Servier. Board Member; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Sanofi. Speaker's Bureau; Self; Novo Nordisk Inc. D. Ziegler: Advisory Panel; Self; Allergan, TrigoCare. Consultant; Self; Mitsubishi Tanabe Pharma Corporation, Mylan, Novartis Pharmaceuticals Corporation, Wörwag. Speaker's Bureau; Self; Berlin-Chemie AG.

Funding

German Ministry of Culture and Science of the State of North Rhine-Westphalia; German Federal Ministry of Health; German Federal Ministry of Education and Research

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