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Epidemiology
Research
Glucose intolerance associated with hypoxia in people living at high altitudes in the Tibetan highland
  1. Kiyohito Okumiya1,2,
  2. Ryota Sakamoto2,3,
  3. Yasuko Ishimoto4,
  4. Yumi Kimura2,
  5. Eriko Fukutomi2,
  6. Motonao Ishikawa5,
  7. Kuniaki Suwa5,
  8. Hissei Imai6,
  9. Wenling Chen2,
  10. Emiko Kato2,
  11. Masahiro Nakatsuka7,
  12. Yoriko Kasahara8,
  13. Michiko Fujisawa2,
  14. Taizo Wada2,
  15. Hongxin Wang9,
  16. Qingxiang Dai9,
  17. Huining Xu9,
  18. Haisheng Qiao10,
  19. Ri-Li Ge11,
  20. Tsering Norboo12,
  21. Norboo Tsering12,
  22. Yasuyuki Kosaka13,
  23. Mitsuhiro Nose2,
  24. Takayoshi Yamaguchi14,
  25. Toshihiro Tsukihara15,
  26. Kazuo Ando2,
  27. Tetsuya Inamura16,
  28. Shinya Takeda13,
  29. Masayuki Ishine17,
  30. Kuniaki Otsuka5,18,
  31. Kozo Matsubayashi2
  1. 1Research Department, Research Institute for Humanity and Nature, Kyoto, Japan
  2. 2Center for Southeast Asian Studies, Kyoto University, Kyoto, Japan
  3. 3Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan
  4. 4Faculty of Medicine, Public Health Nursing, School of Nursing, Mie University, Tsu, Mie, Japan
  5. 5Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
  6. 6Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine, Kyoto, Japan
  7. 7Sakakibara Hakuho Hospital, Tsu, Mie, Japan
  8. 8College of Nursing, Kanto Gakuin University, Yokohama, Japan
  9. 9Affiliated Hospital of Qinghai University, Xining, Qinghai, China
  10. 10Qinghai Academy of Animal and Veterinary Sciences, Xining, Qinghai, China
  11. 11Research Center for High Altitude Medicine, Qinghai University, Xining, Qinghai, China
  12. 12Ladakh Institute of Prevention, Ladakh, India
  13. 13Graduate School of Asian and African Area Studies, Kyoto University, Kyoto, Japan
  14. 14National Institute for Agro-Environmental Sciences, Ibaragi, Japan
  15. 15Faculty of Education and Regional Studies, University of Fukui, Fukui, Japan
  16. 16The Open University of Japan, Chiba, Japan
  17. 17Yasugi Clinic, Shimane, Japan
  18. 18Chronomics & Gerontology, Tokyo Women's Medical University, Tokyo, Japan
  1. Correspondence to Dr Kiyohito Okumiya; okumiyak{at}hotmail.com

Abstract

Objectives To clarify the association between glucose intolerance and high altitudes (2900–4800 m) in a hypoxic environment in Tibetan highlanders and to verify the hypothesis that high altitude dwelling increases vulnerability to diabetes mellitus (DM) accelerated by lifestyle change or ageing.

Design Cross-sectional epidemiological study on Tibetan highlanders.

Participants We enrolled 1258 participants aged 40–87 years. The rural population comprised farmers in Domkhar (altitude 2900–3800 m) and nomads in Haiyan (3000–3100 m), Ryuho (4400 m) and Changthang (4300–4800 m). Urban area participants were from Leh (3300 m) and Jiegu (3700 m).

Main outcome measure Participants were classified into six glucose tolerance-based groups: DM, intermediate hyperglycaemia (IHG), normoglycaemia (NG), fasting DM, fasting IHG and fasting NG. Prevalence of glucose intolerance was compared in farmers, nomads and urban dwellers. Effects of dwelling at high altitude or hypoxia on glucose intolerance were analysed with the confounding factors of age, sex, obesity, lipids, haemoglobin, hypertension and lifestyle, using multiple logistic regression.

Results The prevalence of DM (fasting DM)/IHG (fasting IHG) was 8.9% (6.5%)/25.1% (12.7%), respectively, in all participants. This prevalence was higher in urban dwellers (9.5% (7.1%)/28.5% (11.7%)) and in farmers (8.5% (6.1%)/28.5% (18.3%)) compared with nomads (8.2% (5.7%)/15.7% (9.7%)) (p=0.0140/0.0001). Dwelling at high altitude was significantly associated with fasting IHG+fasting DM/fasting DM (ORs for >4500 and 3500–4499 m were 3.59/4.36 and 2.07/1.76 vs <3500 m, respectively). After adjusting for lifestyle change, hypoxaemia and polycythaemia were closely associated with glucose intolerance.

Conclusions Socioeconomic factors, hypoxaemia and the effects of altitudes >3500 m play a major role in the high prevalence of glucose intolerance in highlanders. Tibetan highlanders may be vulnerable to glucose intolerance, with polycythaemia as a sign of poor hypoxic adaptation, accelerated by lifestyle change and ageing.

  • ALTITUDE MEDICINE
  • EPIDEMIOLOGY

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2015-009728

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