Chiu KC, Chu A, Go VLW, Saad MF. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr 79, 820-825

Division of Clinical Epidemiology and Preventive Medicine, Department of Medicine, University of California-Los Angeles School of Medicine, 924 Westwood Boulevard, Los Angeles, CA 90024, USA.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 06/2004; 79(5):820-5.
Source: PubMed


Although the role of vitamin D in type 2 diabetes is well recognized, its relation to glucose metabolism is not well studied.
We investigated the relation of 25-hydroxyvitamin D [25(OH)D] concentrations to insulin sensitivity and beta cell function.
We enrolled 126 healthy, glucose-tolerant subjects living in California. Insulin sensitivity index (ISI) and first- and second-phase insulin responses (1stIR and 2ndIR) were assessed by using a hyperglycemic clamp.
Univariate regression analyses showed that 25(OH)D concentration was positively correlated with ISI (P < 0.0001) and negatively correlated with 1stIR (P = 0.0045) and 2ndIR (P < 0.0001). Multiple regression analyses confirmed an independent correlation between 25(OH)D concentration and ISI (P = 0.0007). No independent correlation was observed between 25(OH)D concentration and 1stIR or 2ndIR. However, an independent negative relation of 25(OH)D concentration with plasma glucose concentration was observed at fasting (P = 0.0258), 60 min (P = 0.0011), 90 min (P = 0.0011), and 120 min (P = 0.0007) during the oral-glucose-tolerance test. Subjects with hypovitaminosis D (<20 ng/mL) had a greater prevalence of components of metabolic syndrome than did subjects without hypovitaminosis D (30% compared with 11%; P = 0.0076).
The data show a positive correlation of 25(OH)D concentration with insulin sensitivity and a negative effect of hypovitaminosis D on beta cell function. Subjects with hypovitaminosis D are at higher risk of insulin resistance and the metabolic syndrome. Further studies are required to explore the underlying mechanisms.

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Available from: Ken Chiu, Jun 24, 2014
    • "Moreover, the sequestration of vitamin D in the large pool of subcutaneous fat and its lower bio-availability are among other hypotheses contributing to the high prevalence of vitamin D deficiency among the obese population9101143]. Interestingly, the previously reported higher levels of PTH and 1,25(OH)2D in obese subjects have also been proposed as important factors exerting negative feedback control over the synthesis of 25(OH)D in the liver, which in turn secretes less insulin and deteriorates insulin sensitivity, promoting insulin resistance and type 2 diabetes mellitus, weight gain, hypertension, left ventricular hypertrophy as well as hypovitaminosis D among this population [10,16,32,42,444546. These findings provide initial evidence that the distribution of fat may be associated with vitamin D status, but this relation may be dependent on metabolic factors [47]. "
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    ABSTRACT: Considering the controversial results regarding the relationship between vitamin D levels and bone mineral density in different populations, the present study was designed to evaluate this correlation in a healthy Iranian population.
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    • "Vitamin D has been well recognized for its role in regulating extracellular calcium flux, and insulin secretion is known as a calcium dependent process [35] . Several studies reported an impaired insulin release in association with vitamin D defi- ciency [11, 36, 37], and vitamin D supplementation has been shown to improve insulin release in randomized controlled trials383940. In addition, vitamin D has been proposed to improve insulin resistance by stimulating the expression of insulin receptors [12]. "
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    ABSTRACT: Background Vitamin D homeostasis may play a critical role in glucose metabolism. Little is known on vitamin D deficiency and its association with diabetes in countries of the Arabia Gulf where the population is experiencing a rapid increase in the incidence of diabetes. Methods In a cross-sectional study of 960 adults enrolled in the first National Nutrition Survey of the State of Kuwait (NNSSK), we examined vitamin D status in association with the prevalence of diabetes and prediabetes. Vitamin D status was measured by serum levels of 25-hydroxyvitami D (25(OH)D). Prevalences of diabetes and prediabetes were determined based on fasting glucose and HbA1C levels. Results The median level of serum 25(OH)D in Kuwaiti adults was 13.8 ng/ml. Approximately 56 % of the Kuwaiti adults had vitamin D inadequacy (25(OH)D = 12–19.9 ng/ml), and 27 % had vitamin D deficiency (25(OH)D < 12 ng/ml). The prevalences of prediabetes and diabetes were 40 and 27 %, respectively. Vitamin D inadequacy (OR = 1.7, 95 % CI: 1.0–2.9) and deficiency (OR =2.0, 95 % CI: 1.1–3.3) was each associated with about two-fold increased odds of prediabetes compared to sufficient vitamin D status (25(OH)D ≥20 ng/ml). Vitamin D inadequacy (OR =2.1, 95 % CI: 1.2–3.7) and deficiency (OR =2.0, 95 % CI: 1.1–3.9) were also associated with two-fold increased odds of diabetes. Conclusions Data from Kuwaiti’s first nutrition nutritional survey suggests a very high prevalence of vitamin D deficiency in Kuwaiti adults. Associations of low vitamin D status and high prevalence of diabetes point to the need of continuous monitoring of vitamin D status and further evaluating potential health consequences in this high-risk population.
    Preview · Article · Dec 2015 · BMC Public Health
    • "visceral fat; CT, computer tomography ; DEXA, dual-energy X-ray absorptiometry; GIR, glucose infusion rates; HOMA, homeostasis model assessment; IR, insulin resistance; PCOS, polycystic ovary syndrome; T2DM, type 2 diabetes mellitus D deficiency (vitamin D <50 nmol/L) in 50% of women and 31% of men living at latitudes >35 degrees south, which includes Melbourne, the location of the current study [6]. Low vitamin D levels have been found in type 2 diabetes mellitus (T2DM) and correlate with obesity, pancreatic beta cell dysfunction , and insulin resistance (IR) and risk of developing T2DM [7] [8] [9] [10]. Supplementation of vitamin D has been shown to improve IR [11] and prevent T2DM [9]. "
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    ABSTRACT: Polycystic Ovary Syndrome (PCOS) is underpinned by IR. In PCOS, the relationships between vitamin D, adiposity and IR are unclear. We aim to explore these relationships in lean and overweight women with PCOS. This is a cross-sectional study conducted in a tertiary medical centre. Participants included 42 women with PCOS and 34 controls without PCOS. Vitamin D and metabolic markers were measured. Detailed body composition and gold standard hyperinsulinaemic euglycaemic clamps were performed. The main outcome measures were plasma levels of vitamin D, adiposity measures and glucose infusion rate (GIR). Vitamin D levels were lower in overweight women with PCOS compared with overweight controls (31.6 and 46.1 nmol/nmol respectively, p = 0.01). Vitamin D was not associated with IR after adjustment for confounders; however, there was a significant interaction between PCOS and % body fat. Further analysis by PCOS status revealed that vitamin D was associated with IR in the PCOS group (β coefficient 2.1, 95% CI 0.2-4.0, p = 0.03), but not in the non-PCOS group. Vitamin D is associated with IR in women with PCOS, but not in controls. Large intervention studies are needed to determine if vitamin D supplementation can improve IR in PCOS. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Aug 2015 · Molecular Nutrition & Food Research
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