ABSTRACTBackground: Type 2 Diabetes Mellitus (T2DM) is characterized by hyperglycemia and insulin resistance with HbA1c as the main indicator. Vitamin D plays a role in glucose metabolism through modulation of insulin sensitivity and anti-inflammatory effects, but the relationship between vitamin D and HbA1c still shows varied results. Objective: This review aims to analyze the effect of vitamin D on HbA1c levels in T2DM patients based on published studies. Methods: This study is a narrative review was conducted by searching databases including PubMed, ScienceDirect, and Google Scholar over the past 10 years. Screening using Mendeley application yielded 10 articles meeting the criteria. Variables studied included HbA1c levels, simple carbohydrate intake, fiber intake, vitamin D intake, and oral hypoglycemic agent adherence.Results Several studies show that vitamin D can reduce HbA1c levels through increased insulin sensitivity and reduced inflammation. However, other studies report no significant effect of vitamin D on HbA1c, especially in individuals with sufficient vitamin D levels. Conclusion: Vitamin D potentially plays a role in controlling HbA1c levels in T2DM patients, especially in individuals with vitamin D deficiency. Further research with more rigorous designs is still needed to confirm the effect of vitamin D on HbA1c.Keywords: Type 2 diabetes mellitus; HbA1c; inflammation; insulin sensitivity; vitamin d ABSTRAKLatar Belakang: Diabetes Mellitus Tipe 2 (T2DM) ditandai dengan hiperglikemia dan resistensi insulin dengan HbA1c sebagai indikator utama. Vitamin D berperan dalam metabolisme glukosa melalui modulasi sensitivitas insulin dan efek anti-inflamasi, namun hubungan antara vitamin D dan HbA1c masih menunjukkan hasil bervariasi. Tujuan: Menganalisis efek vitamin D terhadap kadar HbA1c pada penderita T2DM berdasarkan studi yang telah dipublikasikan. Metode: Tinjauan naratif dilakukan dengan menelusuri basis data PubMed, ScienceDirect, dan Google Scholar dalam 10 tahun terakhir. Screening menggunakan aplikasi Mendeley menghasilkan 10 artikel yang sesuai kriteria. Variabel yang diteliti meliputi kadar HbA1c, asupan karbohidrat sederhana, asupan serat, asupan vitamin D, dan kepatuhan minum OHO. Hasil: Beberapa studi menunjukkan vitamin D dapat menurunkan kadar HbA1c melalui peningkatan sensitivitas insulin dan pengurangan peradangan. Namun, beberapa penelitian lain melaporkan tidak ada efek signifikan dari vitamin D terhadap HbA1c, terutama pada individu dengan kadar vitamin D cukup. Kesimpulan: Vitamin D berpotensi berperan dalam pengendalian kadar HbA1c pada penderita T2DM, terutama pada individu dengan defisiensi vitamin D. Penelitian lebih lanjut dengan desain lebih ketat masih diperlukan untuk memastikan efek vitamin D terhadap HbA1c.Kata Kunci: Diabetes mellitus tipe 2; HbA1c; inflamasi; sensitivitas insulin; vitamin d
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