Glucose intolerance associated with hypoxia in people living at high altitudes in the Tibetan highland

• Published in: BMJ open 2016-02, Vol.6 (2), p.e009728-e009728
• Main Authors: Okumiya, Kiyohito, Sakamoto, Ryota, Ishimoto, Yasuko, Kimura, Yumi, Fukutomi, Eriko, Ishikawa, Motonao, Suwa, Kuniaki, Imai, Hissei, Chen, Wenling, Kato, Emiko, Nakatsuka, Masahiro, Kasahara, Yoriko, Fujisawa, Michiko, Wada, Taizo, Wang, Hongxin, Dai, Qingxiang, Xu, Huining, Qiao, Haisheng, Ge, Ri-Li, Norboo, Tsering, Tsering, Norboo, Kosaka, Yasuyuki, Nose, Mitsuhiro, Yamaguchi, Takayoshi, Tsukihara, Toshihiro, Ando, Kazuo, Inamura, Tetsuya, Takeda, Shinya, Ishine, Masayuki, Otsuka, Kuniaki, Matsubayashi, Kozo
• Format: Article
• Language: English
• Subjects: Adaptation; Adult; Aged; Aged, 80 and over; Aging; Altitude; Comorbidity; Cross-Sectional Studies; Developing countries; Diabetes; Diabetes Mellitus - epidemiology; Epidemiology; Female; Glucose; Glucose Intolerance - epidemiology; Health facilities; Hemoglobin; Humans; Hypertension; Hypotheses; Hypoxia; Hypoxia - epidemiology; LDCs; Life Style; Lifestyles; Livestock; Male; Middle Aged; Nomads; Older people; Population; Prevalence; Rural areas; Rural Population - statistics & numerical data; Socioeconomic Factors; Tibet - epidemiology; Transients and Migrants - statistics & numerical data; Urban Population - statistics & numerical data
• ISSN: 2044-6055; 2044-6055
• DOI: 10.1136/bmjopen-2015-009728

ObjectivesTo 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.DesignCross-sectional epidemiological study on Tibetan highlanders.ParticipantsWe 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 measureParticipants 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.ResultsThe 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 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.