The Status Of Vitamin D And Its Relationship With Glucose Tolerance Among Middle-aged And Elderly Individuals

Objective To investigate the nutritional status of 25-hydroxyvitamin D and the prevalence of vitamin D deficiency; and to compare vitamin D levels based on the spectrum of glucose tolerance among middle-aged and elderly individuals.Methods We used cluster random sampling methods to selected 10100 permanent residents (reside in Lanzhou City at least 5 years) aged 40-75 years in three communities (Tianqingjiayuan Community, Wuquanshan community and Wudulu community) in urban district, Lanzhou. Each of the participants had the questionnaire survey, physical examination and some related biochemical examinations. The 1999 World Health Organization diagnostic criteria were used to diagnose prediabetes and diabetes. Vitamin D status was defined as’deficiency’ (25OHD<20 ng/ml),’insufficiency’(25OHD>20, and<30 ng/ml) and’sufficiency’(25OHD>30 ng/ml). IBM SPSS STATISTICS 19 software (IBM Corporation, Armonk, NY, USA) was used to investigate the nutritional status of 25-hydroxyvitamin D and the prevalence of vitamin D deficiency; and to compare the vitamin D status based on the spectrum of glucose tolerance.Results (1) 10038 subjects were deemed eligible for and included in the study,2902 (28.9%) subjects were male and 7136 (71.1%) subjects were female among them. All participants aged 40-75 years and the mean year of them is 58.0±8.5 years old. The mean body mass index of the subjects is 24.2±3.3 kg/m2, and the prevalence of overweight and obesity are 32.6%.4.5%, respectively. The mean concentration of 25OHD is 16.4±7.0 ng/ml, the concentration of male is higher than female (P<0.001). The percent of subjects with family history of diabetes is 18.2%. The prevalence of diabetes, hypertention and dyslipidemia are 24.8%,37.2%,66.6%, respectively. (2) The percents of people with vitamin D deficiency, vitamin D insufficiency and sufficiency are 75.2%,22.6%,2.3%, respectively. The percent of vitamin D insufficiency is up to 97.7%. The prevalence of vitamin D deficiency of female is higher than male (P<0.001). Some risk factors of prediabetes and diabetes were significantly increased in the vitamin D deficient compared with the vitamin D sufficient group (LDL cholesterol, triglycerides, BMI, etc). (3) People with normal glucose tolerance (NGT,47.3%), prediabetes (IGR,28.0%) or diabetes (DM,24.8%) aged 40-75 years were included in the study. Diabetes subjects have older mean age than NGT and IGR individuals (all P<0.05). The DM prevalence of male is higher than female (32.3% vs 21.7%, P<0.001). As expected, subjects with prediabetes and diabetes were older; had greater glucose levels, Alc, LDL cholesterol, triglycerides, BMI, waist circumference, SBP; and had higher percentages of individuals with hypertention or dyslipidaemia than subjects with NGT (all P<0.05). (4) Logistic regression analyses was used to investigate the risk factors of vitamin D deficiency. Results showed that female, older age, higher body mass index, smoking and dyslipidemia were risk factor, and drinking tea, consumption of nutrients, more physical activity decresed the risk for vitamin D deficiency. The prevalences of vitamin D deficiency were higher among female, aged 60-75 years and obesity (BMI≥30 kg/m2) individual in prediabetes and diabetes (all P<0.05). The prevalences of vitamin D deficiency were lower among people who drink tea and coffee, eat organ meats and consumption of nutrients (all P<0.05). (5) After adjusted confounding factors, the difference in 25OHD concentration between people with NGT and prediabetes was not significant (16.5 vs 16.0 ng/ml, P=0.773), but the 25OHD concentration of diabetes were higher than that of subjects with NGT (16.5 vs 16.5 ng/ml, P=0.025) and prediabetes (16.5 vs 16.0 ng/ml, P=0.032) after adjusting confounders. There was no difference in the prevalence of vitamin D deficiency between people with NGT and diabetes (74.7% vs 74.0%, P=0.535), but the prevalence vitamin D deficiency of prediabetes were higher than that of people with NGT (77.0% vs 74.7%, P=0.024) and diabetes (77.0% vs 74.0%, P=0.012). The concentration of plasma 25OHD had the negative relationship with fasting blood glucose, postprandial blood gluclose, glycated hemoglobin, and the relative index were -0.035,-0.045,-0.024, respectively (all P<0.05).Conclusions The prevalence of vitamin D deficiency among the middle-aged and elderly residents in Lanzhou urban district was high. We should enhance the early screening and management during vitamin D deficiency sufferers as soon as possible, and control the spread of abnormal vitamin D status. Female, older age, higher body mass index, smoking and dyslipidemia were risk factor, and drinking tea, consumption of nutrients, more physical activity decresed the risk of vitamin D deficiency. The concentration of serum 25OHD had the negative relationship with fasting blood glucose, postprandial blood gluclose, glycated hemoglobin. Although vitamin D status was significantly different across the spectrum of glucose tolerance among middle-aged and elderly Chinese individuals, the difference was not clinically significant. The results however highlight the very high prevalence of vitamin D deficiency in this population and should raise the awareness of this important public health issue among healthcare providers.