BACKGROUND: Both obesity and type 2 diabetes are associated with hypovitaminosis D. We investigated the impact of body mass index (BMI) status on the relationship of serum 25-hydroxyvitamin D (25OHD) concentration with insulin sensitivity. DESIGN: This cross-sectional study enrolled 126 healthy and glucose-tolerant subjects. The participants were divided into two groups based on BMI: normal weight (n = 68) and overweight (n = 58). Insulin sensitivity index (ISI) and beta-cell function were assessed by using hyperglycaemic clamps. Serum 25OHD concentration was determined in the fasting samples. RESULTS: The correlation of serum 25OHD with ISI was much stronger in the overweight group (r = 0·5271, P < 0·0001) than in the normal weight group (r = 0·2836, P = 0·002). The correlation remained significant in the overweight group (r = 0·3620, P = 0·002), but not in normal weight group after adjusting for age, gender, BMI, season of study, ethnicity and exercise. Nonlinear regression analysis revealed that when serum 25OHD concentration was > 40 ng mL(-1), the association between serum 25D concentrations and insulin sensitivity plateaued. CONCLUSIONS: We observed stronger associations of serum 25OHD with insulin sensitivity in overweight than normal weight subjects, suggesting that overweight subjects with hypovitaminosis D may benefit more from vitamin D replacement than normal weight subjects. Furthermore, the optimal serum 25OHD concentration for insulin sensitivity is about 40 ng mL(-1). As more than 60% of the US population is overweight and hypovitaminosis D is highly prevalent in overweight subjects, hypovitaminosis D has a large population attributable risk for type 2 diabetes.
BACKGROUND: Both obesity and type 2 diabetes are associated with hypovitaminosis D. We investigated the impact of body mass index (BMI) status on the relationship of serum 25-hydroxyvitamin D (25OHD) concentration with insulin sensitivity. DESIGN: This cross-sectional study enrolled 126 healthy and glucose-tolerant subjects. The participants were divided into two groups based on BMI: normal weight (n = 68) and overweight (n = 58). Insulin sensitivity index (ISI) and beta-cell function were assessed by using hyperglycaemic clamps. Serum 25OHD concentration was determined in the fasting samples. RESULTS: The correlation of serum 25OHD with ISI was much stronger in the overweight group (r = 0·5271, P < 0·0001) than in the normal weight group (r = 0·2836, P = 0·002). The correlation remained significant in the overweight group (r = 0·3620, P = 0·002), but not in normal weight group after adjusting for age, gender, BMI, season of study, ethnicity and exercise. Nonlinear regression analysis revealed that when serum 25OHD concentration was > 40 ng mL(-1), the association between serum 25D concentrations and insulin sensitivity plateaued. CONCLUSIONS: We observed stronger associations of serum 25OHD with insulin sensitivity in overweight than normal weight subjects, suggesting that overweight subjects with hypovitaminosis D may benefit more from vitamin D replacement than normal weight subjects. Furthermore, the optimal serum 25OHD concentration for insulin sensitivity is about 40 ng mL(-1). As more than 60% of the US population is overweight and hypovitaminosis D is highly prevalent in overweight subjects, hypovitaminosis D has a large population attributable risk for type 2 diabetes.
Authors: Ji Hyun Kang; Sang Soo Kim; Seung Su Moon; Won Jin Kim; Min Jung Bae; Bo Gwang Choi; Yun Kyung Jeon; Bo Hyun Kim; Yong Ki Kim; In Joo Kim Journal: Endocrinol Metab (Seoul) Date: 2013-06-18
Authors: Barbora de Courten; Aya Mousa; Negar Naderpoor; Helena Teede; Maximilian P J de Courten; Robert Scragg Journal: Trials Date: 2015-08-07 Impact factor: 2.279