The role of vitamin D deficiency and thyroid dysfunction on blood glucose regulation in patients with type 2 diabetes mellitus: A retrospective cohort study



25 hydroxi Vitamin D, Thyroid dysfunction, Type 2 diabetes mellitus, Blood glucose regulation


Background/Aim: In patients with diabetes mellitus (DM), complications due to hyperglycemia decrease the quality of life and increase mortality. Vitamin D deficiency and thyroid dysfunction negatively affect blood glucose regulation. We aimed to demonstrate effects of treatment of vitamin D deficiency and thyroid dysfunction on blood glucose regulation. This study aimed to reduce the complications that may develop due to hyperglycemia. Methods: In this retrospective cohort study, Type 2 DM patients admitted to our clinic between 2015-2018 were reviewed from hospital registry. Patients who did not attend to their control visits for DM at the 0th, 3rd and 6th months and those with the exclusion criteria were not included. Patients who regularly attended diabetes controls at the 0th, 3rd and 6th months were determined. Among them, those with 25-hydroxy (OH) vitamin D, glycated hemoglobin (HbA1c), fasting blood glucose (FBG), postprandial blood glucose (PPG), free T4, free T3, thyroid stimulating hormone (TSH) values in the hospital registry were sought. Patients with vitamin D deficiencies and thyroid disorders who began treatment at the 0th month were finally included in the study, and the effects of vitamin D replacement treatment and thyroid dysfunction treatment on blood glucose regulation parameters at the 3rd and 6th months were examined. Results: HbA1c levels significantly decreased in Type 2 DM patients whose vitamin D levels were within normal limits at the 3rd month after receiving vitamin D replacement therapy (P=0.023). Vitamin D and HbA1c levels at the 3rd month controls were negatively correlated (r=-0.23, P=0.016, respectively). There were no significant differences in FBG and PPG levels at the 3rd month (P=0.063, P=0.361, respectively). In type 2 DM patients with hypothyroidism at the 0th month who were euthyroid at the 3rd month, there were no statistically significant differences in HbA1c, FBG and PPG (P=0.202, P=0.14, P=0.40, respectively). Six type 2 DM patients became euthyroid at the 3rd and 6th months after beginning levothyroxine treatment at the 0th month, and six patients became euthyroid at the 3rd and 6th months after hyperthyroidism treatment. Two patients had their FBG, and PPG values measured. Due to the insufficient sample size, statistical significance of differences in HbA1c, FBG and PPG levels could not be determined. Conclusion: Vitamin D replacement treatment had positive effects on blood glucose regulation in DM patients with vitamin D deficiency. The effects of vitamin D on blood glucose regulation should be evaluated by HbA1c. Thyroid dysfunctions were not sufficiently questioned during the three-month follow-up of DM patients, so its effects on blood glucose regulation could not be evaluated. Thyroid dysfunction should be questioned in the 3-month follow-up of DM patients and thyroid function tests should be requested.


Download data is not yet available.


Sakin A, Sahin S, Sakin A, Atci M, Geredeli Ç, Cihan Ş. Effect of type 2 diabetes mellitus on survival in metastatic pancreatic cancer. Journal of Surgery and Medicine, 2021;5(1):17-21. doi: 10.28982/josam.840948.

Nasri H, Rafieian-Kopaei M. Effect of Vitamin D on insulin resistance and nephropathy in type 2 diabetes. J Res Med Sci. 2014;19(6):581–2.

Sacerdote A, Dave P, Lokshin V, Bahtiyar G. Type 2 Diabetes Mellitus, Insulin Resistance, and Vitamin D. Curr Diab Rep. 2019;19(10):101 doi:10.1007/s11892-019-1201-y.

Elgazar EH, Esheba NE, Shalaby SA, Mohamed WF. Thyroid dysfunction prevalence and relation to glycemic control in patients with type 2 diabetes mellitus. Diabetes Metab Syndr Clin Res Rev. 2019;13(4):2513–7. doi:10.1016/j.dsx.2019.07.020.

Koçak F, Köseoğlu B, Tomruk Sütbeyaz S. Impact of vitamin D on mobilization, pulmonary function tests, grip strength and functionality in patients with spinal cord injury: A cross-sectional study. Journal of Surgery and Medicine, 2020;4(2):120-5. doi: 10.28982/josam.689130.

Kositsawat J, Freeman VL, Gerber BS, Geraci S. Association of A1C levels with vitamin D status in U.S. adults: data from the National Health and Nutrition Examination Survey. Diabetes Care. 2010;33(6):1236-8. doi: 10.2337/dc09-2150.

Kalra S, Aggarwal S, Khandelwal D. Thyroid Dysfunction and Type 2 Diabetes Mellitus: Screening Strategies and Implications for Management. Diabetes Ther. 2019;10(6):2035-44. doi: 10.1007/s13300-019-00700-4.

Wang C. The Relationship between Type 2 Diabetes Mellitus and Related Thyroid Diseases. J Diabetes Res. 2013;2013:390534. doi: 10.1155/2013/390534.

Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96(1):53-8. doi: 10.1210/jc.2010-2704.

Türkiye Endokrinoloji ve Metabolizma Derneği (TEMD). Osteoporoz ve metabolik kemik hastalıkları tanı ve tedavi kılavuzu. Bölüm 13. Vitamin D Eksikliği. Ankara; 2020.

Tunceli K, Bradley CJ, Nerenz D, Williams LK, Pladevall M, Elston Lafata J. The impact of diabetes on employment and work productivity. Diabetes Care. 2005;28(11):2662-7. doi: 10.2337/diacare.28.11.2662.

Villaggio B, Soldano S, Cutolo M. 1,25-dihydroxyvitamin D3 downregulates aromatase expression and inflammatory cytokines in human macrophages. Clin Exp Rheumatol. 2012;30(6):934-8.

Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res. 2011;31(1):48-54. doi: 10.1016/j.nutres.2010.12.001.

Cigerli O, Parildar H, Unal AD, Tarcin O, Erdal R, Guvener Demirag N. Vitamin D deficiency is a problem for adult out-patients? A university hospital sample in Istanbul, Turkey. Public Health Nutr. 2013;16(7):1306-13. doi: 10.1017/S1368980012003588.

Bayani MA, Akbari R, Banasaz B, Saeedi F. Status of Vitamin-D in diabetic patients. Caspian J Intern Med. 2014 Winter;5(1):40-2. PMID: 24490013; PMCID: PMC3894470.

Holick MF. Vitamin D for health and in chronic kidney disease. Semin Dial. 2005;18(4):266-75. doi: 10.1111/j.1525-139X.2005.18402.x.

Forouhi NG, Ye Z, Rickard AP, Khaw KT, Luben R, Langenberg C and et al. Circulating 25-hydroxyvitamin D concentration and the risk of type 2 diabetes: results from the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort and updated meta-analysis of prospective studies. Diabetologia. 2012;55(8):2173-82. doi: 10.1007/s00125-012-2544-y.

Mirhosseini N, Vatanparast H, Mazidi M, Kimball SM. The Effect of Improved Serum 25-Hydroxyvitamin D Status on Glycemic Control in Diabetic Patients: A Meta-Analysis. J Clin Endocrinol Metab. 2017;1;102(9):3097-3110. doi: 10.1210/jc.2017-01024.

Wu C, Qiu S, Zhu X, Li L. Vitamin D supplementation and glycemic control in type 2 diabetes patients: A systematic review and meta-analysis. Metabolism. 2017;73:67-76. doi: 10.1016/j.metabol.2017.05.006.

Lee CJ, Iyer G, Liu Y, Kalyani RR, Bamba N, Ligon CB and et al. The effect of vitamin D supplementation on glucose metabolism in type 2 diabetes mellitus: A systematic review and meta-analysis of intervention studies. J Diabetes Complications. 2017;31(7):1115-26. doi: 10.1016/j.jdiacomp.2017.04.019.

Krul-Poel YH, Westra S, ten Boekel E, ter Wee MM, van Schoor NM, van Wijland H and et al. Effect of Vitamin D Supplementation on Glycemic Control in Patients With Type 2 Diabetes (SUNNY Trial): A Randomized Placebo-Controlled Trial. Diabetes Care. 2015;38(8):1420-6. doi: 10.2337/dc15-0323.

Jali MV, Kambar S, Jali SM, Pawar N, Nalawade P. Prevalence of thyroid dysfunction among type 2 diabetes mellitus patients. Diabetes Metab Syndr. 2017;11 Suppl 1:S105-S108. doi: 10.1016/j.dsx.2016.12.017.

Hage M, Zantout MS, Azar ST. Thyroid disorders and diabetes mellitus. J Thyroid Res. 2011;2011:439463. doi:10.4061/2011/439463.

Ogbonna SU, Ezeani IU, Okafor CI, Chinenye S. Association between glycemic status and thyroid dysfunction in patients with type 2 diabetes mellitus. Diabetes Metab Syndr Obes. 2019;12:1113-22. doi: 10.2147/DMSO.S204836.

Bilic-Komarica E, Beciragic A, Junuzovic D. Effects of treatment with L-thyroxin on glucose regulation in patients with subclinical hypothyroidism. Med Arch. 2012;66(6):364-8. doi: 10.5455/medarh.2012.66.364-368.






Research Article

How to Cite

Açıkgöz B, Bozkurt E. The role of vitamin D deficiency and thyroid dysfunction on blood glucose regulation in patients with type 2 diabetes mellitus: A retrospective cohort study. J Surg Med [Internet]. 2021 May 1 [cited 2023 Dec. 2];5(5):529-33. Available from: