Vitamin D and Improved Insulin Levels

Research synthesisModerate evidenceModerate effect3 studies · 3 beneficial · 0 neutral · 0 harmful

Across 3 studies, all reported beneficial effects on insulin levels, with a predominant moderate effect size. The most studied dose was 1000 IU/day, and effects were observed in clinical populations including gestational diabetes, type 2 diabetes, and metabolic-associated fatty liver disease. Study durations ranged up to 12 weeks, with a median of 42 days.

Studied populations: women with gestational diabetes, adults with type 2 diabetes, patients with metabolic-associated fatty liver disease

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive, but clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed).

Generated Jul 14, 2026

Doses used in studies

IU/day: 1,000 (median 1,000, IQR 1,000–1,000) — 1 study

Time to effect

Median: 6 weeks · IQR 6 weeks–6 weeks · Range 6 weeks–6 weeks — Reported in 1 of 3 studies

3 of 3 papers

Vitamin D and Evening Primrose Oil Administration Improve Glycemia and Lipid Profiles in Women with Gestational Diabetes.
- 2016-01-19
- RCT · n = 60
- Lipids 51(3)
- - Mehri Jamilian
  - Maryam Karamali
  - Mohsen Taghizadeh
  - Nasrin Sharifi
  - Zahra Jafari
  - Mohammad Reza Memarzadeh
  - Mahnaz Mahlouji
  - Zatolla Asemi
- PubMed: 26781763
- DOI: 10.1007/s11745-016-4123-3
9 Insights on
- Improved Insulin Levels
- High evidence
- Clinical
serum insulin concentrations (-2.0 ± 5.3 vs. +4.6 ± 10.7 µIU/mL, P = 0.004)
Effect
Beneficial
Effect size
Moderate
Significant
Yes
Dose
1000 IU/day
The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.
- 2025-07-30
- Meta-Analysis
- Nutrients 17(15)
- - Enny Probosari
  - Hertanto W Subagio
  - Heri-Nugroho
  - Banundari Rachmawati
  - Siti F Muis
  - Kevin C Tjandra
  - Dwi Adiningsih
  - Tri I Winarni
- PubMed: 40806075
- DOI: 10.3390/nu17152489
6 Insights on
- Improved Insulin Levels
- High evidence
- Rigorous Journal
- Clinical
Significant differences were found at 12-week follow-up in insulin level (MD(-3.59) [95% CI: -6.93, -0.25])
Effect
Beneficial
Effect size
Small
Significant
Yes
Effect of Vitamin D Supplementation on Metabolic Parameters in Patients with Metabolic-Associated Fatty Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
- 2026-04
- Meta-Analysis
- The Journal of nutrition 156(4)
- - Bowen Yu
  - Junyan Liu
  - Fangfang Bu
  - Hongli Yan
  - Chen Chen
  - Yanfei Li
  - Yifei Sun
  - Yaqin Wang
  - Junhua Yuan
- PubMed: 41478593
- DOI: 10.1016/j.tjnut.2025.101314
9 Insights on
- Improved Insulin Levels
- High evidence
- Clinical
Pooled analysis demonstrated that vitamin D supplementation significantly reduced: ... insulin (-0.60, 95% CI: -1.15, -0.05)
Effect
Beneficial
Effect size
Moderate
Significant
Yes

Vitamin D and Improved Insulin Levels

Vitamin D and Evening Primrose Oil Administration Improve Glycemia and Lipid Profiles in Women with Gestational Diabetes.

The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.

Effect of Vitamin D Supplementation on Metabolic Parameters in Patients with Metabolic-Associated Fatty Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.