title: The effects of oral vitamin D on insulin resistance in pre-diabetic patients.
abstract: BACKGROUND
  Some epidemiological and interventional studies have shown the role of vitamin D on insulin secretion and resistance. A previous study in our center showed that intramuscular vitamin D decreases insulin sensitivity in pre-diabetic patients. We investigated the role of oral vitamin D on the insulin sensitivity index and insulin resistance in pre-diabetic patients.
  
  
  METHODS
  In a randomized clinical trial, we divided 45 people with pre-diabetes aged 47.4 ± 6.6 (range 33-61) years into three groups: group A subjects treated with 50,000 IU oral vitamin D and 500 mg calcium carbonate (n = 21), group B subjects treated with a single 300,000 IU intramuscular vitamin D and 500 mg calcium carbonate (n = 9), and group C subjects treated with 500 mg calcium carbonate alone (n = 15). Serum 25-hydroxyvitamin D [25(OH) D] was measured at baseline. If it was less than 75 nmol/l, 50,000 IU vitamin D was given weekly, and if serum 25(OH) D was more than that, vitamin D was administered every 2 weeks. Before and after 12 weeks of treatment, a 75-g glucose tolerance test was performed. We used paired t-test and analysis of variance (ANOVA) to analyze the data. P values less than 0.05 were considered significant.
  
  
  RESULTS
  Mean (SD) of serum vitamin D increased from 77.5 ± 39.2 to 118.8 ± 56.3 nmol/l (P = 0.009) in group A and from 80 ± 36 to 102.8 ± 43.3 nmol/l (P = 0.053) in group B, and decreased from 44.8 ± 18.3 to 34.6 ± 13.9 nmol/l (P = 0.06) in group C. Insulin sensitivity index (Matsuda) decreased from 11.4 ± 3 to 9.9 ± 3.2 (P = 0.046) in group A, but in comparison with other groups, it was not significant.
  
  
  CONCLUSIONS
  Oral vitamin D had no effect on insulin sensitivity in pre-diabetes patients in 12 weeks treatment. A randomized double-blind study with a longer duration of treatment is suggested to investigate the effect of vitamin D on insulin resistance.
authors.affiliation: Department of Internal Medicine and Endocrinology, Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Seyed A
authors.initials: SA
authors.lastname: Hoseini
authors.forename: Ashraf
authors.initials: A
authors.lastname: Aminorroaya
authors.forename: Bijan
authors.initials: B
authors.lastname: Iraj
authors.forename: Massoud
authors.initials: M
authors.lastname: Amini
keywords: Glucose tolerance test; insulin resistance; pre-diabetes; vitamin D; vitamin D deficiency
references.citation: Diabetes Res. 1989 Jul;11(3):141-7
references.pmid: 2697485
references.citation: Diabetes Care. 2006 Mar;29(3):650-6
references.pmid: 16505521
references.citation: Am J Clin Nutr. 1994 May;59(5):1083-7
references.pmid: 8172095
references.citation: Calcif Tissue Int. 1992 Aug;51(2):105-10
references.pmid: 1422948
references.citation: Diabetes Care. 2010 Jun;33(6):1373-5
references.pmid: 20332348
references.citation: Diabetes Care. 1999 Sep;22(9):1462-70
references.pmid: 10480510
references.citation: Diabet Med. 2009 Jan;26(1):19-27
references.pmid: 19125756
references.citation: Br J Nutr. 2010 Feb;103(4):549-55
references.pmid: 19781131
references.citation: Diabetologia. 1985 Jul;28(7):412-9
references.pmid: 3899825
references.citation: Endokrynol Pol. 2012;63(3):191-5
references.pmid: 22744624
references.citation: J Res Pharm Pract. 2012 Oct;1(2):60-5
references.pmid: 24991591
references.citation: Postgrad Med J. 1994 Jun;70(824):440-3
references.pmid: 8029165
references.citation: N Engl J Med. 1997 Sep 4;337(10):670-6
references.pmid: 9278463
references.citation: Arch Intern Med. 2009 Oct 26;169(19):1806-8
references.pmid: 19858440
references.citation: Diabetes Care. 2011 Jan;34 Suppl 1:S11-61
references.pmid: 21193625
references.citation: Eur J Clin Invest. 1997 Jul;27(7):629-33
references.pmid: 9263752
references.citation: Epidemiology. 2008 Sep;19(5):666-71
references.pmid: 18496468
references.citation: Endocr Pract. 2010 Jul-Aug;16(4):600-8
references.pmid: 20350923
references.citation: Nutrition. 2008 Oct;24(10):950-6
references.pmid: 18653316
references.citation: Postgrad Med J. 1998 Jun;74(872):365-6
references.pmid: 9799895
references.citation: Acta Med Scand. 1987;222(4):361-7
references.pmid: 3321925
references.citation: Kidney Int. 1998 May;53(5):1353-7
references.pmid: 9573552
references.citation: Diabetes Care. 2004 Dec;27(12):2813-8
references.pmid: 15562190
references.citation: Diabetes. 2008 Oct;57(10):2619-25
references.pmid: 18591391
references.citation: Diabetologia. 1995 Oct;38(10):1239-45
references.pmid: 8690178
references.citation: Diabetes Care. 2007 Apr;30(4):980-6
references.pmid: 17277040
references.citation: Diabetes Res Clin Pract. 1995 Mar;27(3):181-8
references.pmid: 7555599