{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T10:48:28Z","timestamp":1785408508443,"version":"3.56.0"},"reference-count":48,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T00:00:00Z","timestamp":1779926400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Deanship of Research and Graduate Studies at King Khalid University under the Large Research Project","award":["RGP2\/461\/46"],"award-info":[{"award-number":["RGP2\/461\/46"]}]},{"award":["RGP2\/461\/46"],"award-info":[{"award-number":["RGP2\/461\/46"]}],"id":[{"id":"https:\/\/ror.org\/052kwzs30","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Children and adolescents with type 1 diabetes mellitus (T1DM) may be particularly vulnerable to vitamin D deficiency; however, its association with glycemic control remains incompletely understood. This study aimed to determine the prevalence of vitamin D deficiency among children and adolescents with T1DM and to evaluate its relationship with glycemic control. Methods: This cross-sectional study enrolled individuals aged 1\u201318 years diagnosed with T1DM. Serum 25-hydroxyvitamin D concentrations were assessed, with deficiency defined as &lt;20 ng\/mL, insufficiency as 20\u201329 ng\/mL, and sufficiency as \u226530 ng\/mL. Glycemic control was defined as HbA1c &lt; 9.0% (controlled) versus \u22659.0% (poor control). Multivariable logistic regression was performed to assess the independent association of 25-hydroxyvitamin D with glycemic control. Receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) were conducted to evaluate the diagnostic and potential clinical utility of 25-hydroxyvitamin D levels. Results: A total of 266 participants were included; their median age was 13.0 years (IQR: 10.0\u201315.0), with a slight male predominance (56.8%). Overall, 64.3% of patients had suboptimal 25-hydroxyvitamin D status, including 30.1% with deficiency and 34.2% with insufficiency. Patients with poor glycemic control had significantly lower 25-hydroxyvitamin D levels compared to those with controlled diabetes (21.0 ng\/mL [IQR: 17.0\u201326.0] vs. 35.0 ng\/mL [IQR: 28.0\u201345.0], p &lt; 0.001). A strong negative correlation was observed between HbA1c and 25-hydroxyvitamin D levels (Spearman\u2019s \u03c1 = \u22120.651, p &lt; 0.001). Vitamin D insufficiency was significantly associated with poor glycemic control (aOR = 4.74, 95% CI: 2.48\u20139.32), while vitamin D deficiency was associated with substantially greater odds (aOR = 40.59, 95% CI: 15.55\u2013129.23). The optimal cut-off for predicting poor control was 26.5 ng\/mL, achieving a sensitivity of 75.5% and specificity of 82.2%. Decision curve analysis confirmed that the 25-hydroxyvitamin D model provided superior net benefit compared to treat-all and treat-none strategies across a threshold probability range of 32\u201385%. Conclusions: Vitamin D deficiency and insufficiency are highly prevalent among children and adolescents with T1DM. Lower 25-hydroxyvitamin D levels are independently associated with poorer glycemic control. Serum 25-hydroxyvitamin D demonstrates good diagnostic accuracy and potential clinical utility for risk stratification. Screening for 25-hydroxyvitamin D status and consideration of supplementation may serve as an adjunctive strategy to support metabolic management in this population.<\/jats:p>","DOI":"10.3390\/diagnostics16111661","type":"journal-article","created":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T09:57:43Z","timestamp":1779962263000},"page":"1661","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Diagnostic Value of Serum 25-Hydroxyvitamin D Levels in Predicting Poor Glycemic Control Among Children with Type 1 Diabetes Mellitus: A ROC Curve and Decision Curve Analysis"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-8162-6288","authenticated-orcid":false,"given":"Youssef A.","family":"Alqahtani","sequence":"first","affiliation":[{"name":"Department of Child Health, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0444-5595","authenticated-orcid":false,"given":"Ayed","family":"A. Shati","sequence":"additional","affiliation":[{"name":"Department of Child Health, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ayoub A.","family":"Alshaikh","sequence":"additional","affiliation":[{"name":"Department of Family and Community Medicine, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5141-2804","authenticated-orcid":false,"given":"Ashwag","family":"Asiri","sequence":"additional","affiliation":[{"name":"Department of Child Health, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saleh M.","family":"Alqahtani","sequence":"additional","affiliation":[{"name":"Department of Child Health, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nada Hamzah","family":"Albarqi","sequence":"additional","affiliation":[{"name":"Asser Health Cluster, Ministry of Health Saudi Arabia, Abha 62461, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fatmah Qasim","family":"Shamakhi","sequence":"additional","affiliation":[{"name":"Asser Health Cluster, Ministry of Health Saudi Arabia, Abha 62461, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7611-706X","authenticated-orcid":false,"given":"Ramy Mohamed","family":"Ghazy","sequence":"additional","affiliation":[{"name":"Department of Family and Community Medicine, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia"},{"name":"Tropical Health Department, High Institute of Public Health, Alexandria University, Alexandria 21526, Egypt"},{"name":"Health and Medical Research Centre, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1186\/s12986-022-00696-y","article-title":"Fat-soluble vitamins: Updated review of their role and orchestration in human nutrition throughout life cycle with sex differences","volume":"19","author":"Youness","year":"2022","journal-title":"Nutr. 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