(11.13) Correlation of serum uric acid and vitamin D status in patients with type 2 diabetes: A systematic review and meta-analysis

Vitamin D (VD) deficiency or insufficiency affects nearly one billion people worldwide, which could lead to osteoporosis and exert burden to family and society. The increase of serum uric acid (SUA) level is accompanied by various comorbidities, such as hypertension, diabetes and dyslipidemia. But SUA has its anti-inflammatory effect. Results about previous studies about VD and SUA were inconsistent, and a systematic meta-analysis confirmed that increasing SUA might be associated with increasing 25-hydroxyvitamin D (25OHD) level, while VD deficiency is associated with hyperuricemia. Type 2 diabetes (T2DM) is not only related to VD deficiency, but also belongs to metabolic diseases. The aim of the study was to explore the controversial relationship between SUA and status of VD in patients with T2DM.

Methods:

PubMed, Embase and Cochrane Library databases were searched by using keywords and related words. The quality of the literature was evaluated by Newcastle-Ottawa Scale form. We systematically screened the literature to extract information and data according to inclusion and exclusion criteria. RevMan 5.3 and Stata 13.0 software were conducted for statistical analysis. The Results were expressed as the mean difference (MD) and 95% confidence interval (CI). The heterogeneity was evaluated by I² and Q tests.

Results:

This meta-analysis included 4 studies and 49,304 subjects with T2DM including male and female. The quality of literatures was moderate and high. Statistical analysis: (i) VD sufficiency group (25OHD 20-30 ng/ml) vs. Normal VD (25OHD >30ng/ml) group: MD=9.03 (95% CI: -2.83, 20.88), I²=66%, P=0.03. No source of heterogeneity was found. (ii) VD deficiency group (25OHD< 20ng/ml) vs. VD normal group: MD=29.34 (95% CI: 2.31, 56.36), I²=95%, P< 0.00001. By sensitivity analysis, MD=39.88 (95% CI: 26.87, 52.89), I²=43%, P=0.17, indicated VD deficiency group had higher SUA level. (iii) VD deficiency group vs. VD sufficiency group: MD=14.52 (95% CI: -9.65, 38.69), I²=92%, P< 0.00001. No source of heterogeneity was found.

Discussion/Conclusion:

We cannot prove the causality between VD deficiency or insufficiency and SUA because the studies included were observational, but this meta-analysis reminded us lower SUA level may be related with higher 25OHD level. The possible mechanism is that VD deficiency is a cause of secondary hyperparathyroidism, which could induce hyperuricemia. In patients with T2DM, it is important to manage SUA and 25OHD levels simultaneously to avoid complications such as osteoporosis and gout.