Obesity, diabetes and hypovitaminosis D among women in a rural district of Nepal: Prevalence and risk factors. A population-based study

Abstract

The prevalence of obesity, diabetes, and hypovitaminosis D has increased worldwide over the last decades, and these conditions have reached epidemic proportions. Low- and middleincome countries have experienced the most pronounced rise. South Asians tend to be more susceptible to obesity and diabetes than other ethnicities. Few studies have addressed the prevalence of these conditions among women in rural Nepal. The overall aim of this doctoral thesis was to investigate the prevalence of overweight/obesity, central obesity, diabetes and hypovitaminosis D, and associated risk factors among women in a rural district of Nepal. The thesis is based on two population-based cross-sectional surveys. Survey I was conducted in 2012-2013 among women in a rural district of Nepal (paper 1 and 2), and the outcomes were prevalence of sexually transmitted infections, and prevalence of overweight/obesity and diabetes and associated risk factors. The inclusion criteria were that they were or had been married and >15 years. Pregnancy was an exclusion criterion. Survey II was conducted in 2019-2020, and women who participated in survey I were invited (paper 3). The main outcome was prevalence of diabetes and risk factors and relation with vitamin A and D. In collaboration with female community health volunteers, all eligible participants received verbal information about the project and were invited to participate. In both surveys, information was collected through questionnaire, anthropometric and blood pressure measurements, and blood tests. In paper 1, 1391 women aged 17 to 86 years (43.1 ± 14.4 years) were included. The women belonged to three ethnic groups, and the majority were uneducated. The prevalence of overweight/obesity, and central obesity was examined using cut-offs for Asians for body mass index (BMI) and waist circumference (WC). Altogether, 30.4% of the women were overweight and 12% obese; 34.2% had central obesity, whereas 25.7% exhibited both overweight/obesity and central obesity. Underweight was observed in 9.8%. Altogether 13.7% had hypertension. Intake of instant noodles ≥2 times weekly was associated with increased risk for central obesity and overweight/obesity, however, borderline significant for the latter. Current smoking and having >3 children were associated with a reduced risk for central obesity, although not significant. Hypertension was associated with both overweight/obesity and central obesity. The aim of paper 2 was to assess the prevalence of diabetes and associated risk factors using HbA1c with a cut-off ≥6.5% (≥48 mmol/mol) as a diagnostic tool. HbA1c was analyzed in 757 women, age 17-86 years who were included in the study. We observed a high prevalence of diabetes and prediabetes, 13.5% and 38.5%, respectively. When using a cut-off of 7.0% to increase the specificity, the prevalence of diabetes was 5.8%. Aging, and intake of instant noodles and milk ≥2 times weekly were associated with increased risk for diabetes. Women with diabetes displayed a higher WC than those with normoglycemia, although not significant. The awareness on diabetes was low. The aim of paper 3 was to study the prevalence of hypovitaminosis D (< 50 nmol/L) and risk factors. Altogether 733 women, 21-80 years of age, were included in the analyses, based on completion of vitamin D measurements. Vitamin D deficiency (< 30 nmol/L) and vitamin D insufficiency (30-50 nmol/L) were observed in 6.3% and 42.4%, respectively. Women reporting intake of milk or eggs ≥2 times a week displayed higher vitamin D levels than those with intake < 2 times weekly. Current smokers displayed lower levels of 25(OH)D than never smokers, although borderline significant. Women with vitamin D levels < 50 nmol/L exhibited higher levels of cholesterol, low-density lipoprotein-cholesterol, triglycerides, and HbA1c. Moreover, a regression analysis showed a significant association between hypovitaminosis D, dyslipidemia, and HbA1c elevation. In conclusion, we show that obesity, diabetes, and hypovitaminosis D were highly prevalent among women in all age groups in a rural district of Nepal. Consumption of instant noodles was associated with increased risk both for overweight/obesity, central obesity, and diabetes. Low vitamin D levels seemed to imply increased risk for diabetes and dyslipidemia. Eggs and milk appeared to be the best dietary sources of vitamin D. Our findings show that there is a need for increased awareness at all levels. Our study provides knowledge that could be used to develop preventive and promotive health programs addressing overweight/obesity, diabetes and hypovitaminosis D at community level, thereby slowing down the diabetes epidemics. Moreover, an intervention study with vitamin D supplements to those with vitamin D levels below 50 nmol/L is warranted to explore the effect of metabolic components.