Effect of Vitamin D Supplementation on Glycemic Control in Prediabetes: A Meta-Analysis

Abstract

Clinical research results of vitamin D supplementation in the improvement of prediabetes remain controversial. Accordingly, a literature search was conducted of PubMed, Embase (Ovid), and Web of Science prior to 9 November 2021. Randomized controlled studies reported that the following indicators were included: body mass index (BMI), fasting blood glucose (FBG), 2 h oral glucose tolerance test plasma glucose (2h-PG), hemoglobin A1c (HbA1c), insulin resistance by homeostasis model assessment (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-B), and fasting insulin (FINS). Twenty-nine articles (N = 3792) were included in the present meta-analysis. Intriguingly, vitamin D supplementation resulted in a vast improvement in FBG (standardized mean difference (SMD) = −0.38; 95%CI: −0.59, −0.16), HbA1c (SMD = −0.14; 95%CI: −0.22, −0.06) and FINS (SMD = 0.18; 95%CI: −0.26, −0.09), but not in other outcomes. However, preferred changes were observed in subgroups, as follows: Asia (SMD2h-PG = −0.25, 95%CI: −0.45, −0.04), study duration ≥1 year (SMDHOMA-IR = −0.44, 95%CI: −0.81, −0.06) (SMDHOMA-B = 0.34, 95%CI: 0.01, 0.66), baseline 25(OH)D < 50 nmol/L (SMD2h-PG = −0.23, 95%CI: −0.39, −0.06), and baseline 25(OH)D ≥ 50 nmol/L (SMDHOMA-IR = −0.50, 95%CI: −0.96, −0.03). In conclusion, oral supplementation of vitamin D has shown better effects in improving FBG, HbA1c, and FINS compared with controls among prediabetics; long-term vitamin D supplementation could have additional effects in participants with vitamin D deficiency for 2h-PG, HOMA-IR, and HOMA-B.

Polysaccharides from Dendrobium officinale improve obesity‐induced insulin resistance through the gut microbiota and the SOCS3‐mediated insulin receptor substrate‐1 signaling pathway

“…It tends to increase and remains high during insulin resistance, impairing glucose tolerance. 33 Our results showed that the intervention with DOP in SD rats decreased the fasting blood glucose and improved glucose tolerance. The findings are aligns with a study showing that DOP intervention also improved pancreatic damage and metabolism disorders of bile acid and amino acid in diabetic rats.…”

“…Fasting blood glucose is maintained within a lower range under normal circumstances. It tends to increase and remains high during insulin resistance, impairing glucose tolerance 33 . Our results showed that the intervention with DOP in SD rats decreased the fasting blood glucose and improved glucose tolerance.…”

Association of serum 25-hydroxy vitamin D status with cardiometabolic risk factors and total and regional obesity in southern Iran: Evidence from the PoCOsteo study

“…Nonetheless, some research ndings indicate that vitamin D signi cantly lowers HbA1c in those with prediabetes or diabetes (56-58). Additionally, a number of earlier studies have demonstrated that vitamin D supplementation can lower the risk of developing diabetes in prediabetic persons (53,57,(59)(60)(61). As a result, it appears that su cient vitamin D levels have a positive impact on lowering blood sugar levels, especially in the prediabetic population.…”

The impacts of vitamin D supplementation in adults with metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

“…Nevertheless, the results of current studies were contradictory. Some studies on pre-diabetic patients ( Lemieux et al, 2019 ; Zhang et al, 2021 ) and T2DM patients ( Farrokhian et al, 2017 ; Safarpour et al, 2020 ) have shown the benefits of VDS. A meta-analysis conducted by Zhang et al reported that VDS resulted in a vast improvement in FPG, HbA1c, and FI levels in prediabetics, but not in other parameters ( Zhang et al, 2021 ).…”

“…Some studies on pre-diabetic patients ( Lemieux et al, 2019 ; Zhang et al, 2021 ) and T2DM patients ( Farrokhian et al, 2017 ; Safarpour et al, 2020 ) have shown the benefits of VDS. A meta-analysis conducted by Zhang et al reported that VDS resulted in a vast improvement in FPG, HbA1c, and FI levels in prediabetics, but not in other parameters ( Zhang et al, 2021 ). However, a meta-analysis of 23 RCTs investigating the influence of vitamin D on glycemic control in individuals with T2DM revealed no effect on FPG, HOMA-IR and HbA1c ( Krul-Poel et al, 2017 ).…”