The heightened stress that accompanies urbanization, including relocating from rural areas to cities, may be affecting the hormone levels of people in developing nations, thereby increasing their susceptibility to diabetes and other metabolic disorders, according to new data published in the Journal of Clinical Endocrinology & Metabolism.
“Our findings indicate that people who leave a rural lifestyle for an urban environment are exposed to high levels of stress and tend to have higher levels of the hormone cortisol,” study researcher Peter Herbert Kann, MD, PhD, MA, of Philipp’s University in Marburg, Germany, said in a press release. “This stress is likely contributing to the rising rates of diabetes we see in developing nations.
In their prospective, cross-sectional, diagnostic study, Dr. Kann and colleagues evaluated people from one ethnic group: the Ovahimba people of Namibia in southwestern Africa. Namibia is the second least-densely populated country in the world, with only 38.6% of its residents living in urban areas, according to background information in the study.
For the study, the researchers measured cortisol, blood sugar, cholesterol and other metabolic parameters in 60 Ovahimba people living in Opuwo, the regional capital with a population of 21,000, and in 63 Ovahimba people living at least 50 km from the nearest town or village.
Prevalence of diabetes or glucose metabolism disorders was significantly higher in the urban group when compared with the rural group (28.3% vs. 12.7%; P=.04). Similarly, cortisol levels were significantly higher among those living in urban vs. rural areas.
Furthermore, unfavorable changes were noted in other metabolic parameters in the urban group, including hip circumference (P<.001); waist circumference (P<.001); BMI (P=.014); systolic blood pressure (BP) at rest (P<.001); diastolic BP at rest (P=.002); systolic BP after exercise (P<.001); heart rate after exercise (P=.007); fasting glucose (P<.001); 2-hour glucose by oral glucose tolerance test (P=.002); triglycerides (P=.04); HDL cholesterol (P=.014); and prevalence of metabolic syndrome (P<.001).
The researchers found that the urban group had an increased intake of fast foods and sweets and less physical activity than the rural group, but Dr. Kann noted that the differences in cortisol likely played a large role in these metabolic differences as well.
“The results suggest sociocultural instability caused by urbanization contributes to an increased risk of developing diabetes or another metabolic disorder,” Dr. Kann said. “This is the first prospective study to systematically show the body’s regulation of the hormone cortisol plays a part in the metabolic changes brought on by the shift to an urban lifestyle.”