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
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    • "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.
    Molecular Nutrition & Food Research 08/2015; DOI:10.1002/mnfr.201500259 · 4.60 Impact Factor
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    • "Some animal studies showed that knockout of the vitamin D receptor in diabetic mice was associated with severe albuminuria and glomerulosclerosis [32]. Alternatively, vitamin D might slow the progression of DN by improving insulin secretion, delaying destruction of b-islet cells, affecting osteocalcin and consequently assisting in glucose metabolism [4] [33] [34]. In addition, 1, 25(OH) 2 D 3 is known as a RAS inhibitor due to its negative regulatory effect on renin production [35]. "
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    ABSTRACT: Objective There has been a long history documenting the usage of different vitamin D derivatives as therapy for renal diseases. However, there is no comprehensive assessment of the relation between vitamin D deficiency and risk of diabetic nephropathy (DN). In addition, the effect of vitamin D supplementation on DN is still unclear. The aim of this meta-analysis was to assess these issues by pooling together the results from cross sectional studies and clinical trials. Methods A systematic literature search of PubMed, Scopus, and Google Scholar was conducted up to September 2014. For cross-sectional studies, odds ratio (OR) was used as a measure of the association between vitamin D status and risk of DN, and for clinical trials mean and standard deviation (SD) of the main outcome (urine albumin/creatinine ratio (UACR)) in intervention and placebo groups were considered for analysis. Results The final selected articles were published between 2009 and 2014. A total of 3700 and 219 patients were enrolled in observational and interventional studies, respectively. The pooled ORs from 6 cross-sectional studies was 1.80 (95% CI, 1.25 to 2.59; p=0.002) indicating a significant inverse association between serum vitamin D status and risk of nephropathy in diabetic patients. However, the pooled data of UACR levels in clinical trials suggested no significant change following vitamin D supplementation (17.98; 95% CI, -35.35 to 71.32, p=0.51). Conclusion This meta-analysis showed the higher risk of nephropathy in vitamin D deficient diabetic patients. Causality in this association was not supported by pooling together the results of available clinical trials following vitamin D supplementation
    Nutrition 05/2015; 31(10). DOI:10.1016/j.nut.2015.04.009 · 2.93 Impact Factor
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    • "Vitamin D and calcium insufficiency may negatively influence glycemia, whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism [6] , Vitamin D itself is essential for normal insulin release in response to glucose and for maintenance of glucose tolerance so that vitamin D deficiency results in decreased pancreatic insulin secretion, without altering glucagon secretion [15 ,16 ]. Vitamin D supplementation improves stimulated insulin secretion in response to an oral glucose load in patients with mild (normal fasting serum glucose) [17] [18], type 2 diabetes mellitus, in non-diabetic healthy subjects and in subjects with vitamin D deficiency but not in patients with established type 2 diabetes mellitus [19] [20]. Many researchers have confirmed that vitamin D plays an important role in endothelial function, blood pressure control, calcification of the coronary vasculature, increased vascular resistance, and prevention of CVD [21]. "
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    ABSTRACT: Background: lipid profile had major effect in many diseases worldwide especially atherosclerosis, insulin and vitamin D (vit D) play an important role on the lipids metabolism and its complications. Study aim to evaluate lipid profile level in type 2 diabetes mellitus (DM) with vit D deficiency. Materials and Methods: Descriptive cross sectional study, 120 type2 DM patients aged between 25-80 years old were enrolled, then classified based on vitD results classified into two groups, (<30 ng/ml) considered as cases and (>30 ng/ml) as control groups. VitD, lipid profile (Cholesterol, triglyceride, LDL-C and HDL-C) and glucose were measured in fasting blood samples, using competitive ELISA and Mindray BS-380. Results DM and vitamin D deficient are more common among females. Mean of lipid profile () showed insignificant difference when compared case with control groups, in contrast mean concentration of cholesterol significantly increased in patients who have duration >5 years, in addition no significant differences observed between others lipids and (duration of disease, BMI and gender variations).
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