The Effect of Curcumin on Lipid Profile and Glycemic Status of Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.

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• Dyslipidemia and dysglycemia interact with each other, and are risk factors of macro- and microvascular diseases in T2DM.

Although effective intervention strategies exist for improving glycemic status of T2DM patients, they often need lipid-lowering drugs simultaneously to prevent CVD.

• Novel therapeutic interventions are needed to manage dyslipidemia and dysglycemia in diabetic patients, when statin therapy to treat dyslipidemia, may increase the risk of new-onset diabetes and myopathy.
• Other clinical studies have highlighted the benefits of curcumin supplementation on lipid profile and glycemic status. Clarifying its effects is important for assessing its potential as an alternative and complementary medicine on improving the metabolic status of T2DM patients.
• Overall there is limited evidence and further research is required.

Introduction

This meta-analysis aimed to evaluate the effects of curcumin on lipid profile in patients with type 2 diabetes mellitus (T2DM), including: serum triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL-c), and/or high-density lipoprotein cholesterol (HDL-c). Fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) were also assessed.

Methods

A search was performed on Pubmed, Embase, Web of Sciences, and the Cochrane Library up to March 2022. Quality assessment of all included studies was performed.

Results

9 studies were included in the review, with a total of 604 participants (284 in the curcumin group and 281 in the control group) of mean age from 41 to 60.95 years. Curcumin forms varied among the studies including, turmeric, curcuminoids, and curcumin. The dosage of curcumin in the intervention group ranged from 80 to 2100 mg/day. The duration of intervention was between 4 weeks and 3 months in different studies.

• Effect of Curcumin on TG: A difference was observed between curcumin supplementation and control (p = 0.03), indicating curcumin could reduce serum TG.
• Effect of Curcumin on TC: The mean difference in net changes of TC between intervention and control groups was −8.91mg/dL (p = 0.001), suggesting that curcumin could decrease serum TC.
• Effect of Curcumin on LDL-C: No difference in the net change of LDL-c between intervention and control groups (p = 0.26).
• Effect of Curcumin on HDL-C: No difference in HDL-c between intervention and control groups (p = 0.56).
• Effect of Curcumin on FBG: Curcumin reduced blood glucose levels compared with control treatment (p = 0.002). The effect was greater in trials with the treatment duration >8w (p = 0.037), curcumin dose >100mg/day (p = 0.004), and with the participants receiving the other therapy (p = 0.002).
• Effect of Curcumin on HbA1c: HbA1c (%) decreased in the intervention group compared with the control group (p ≤ 0.001).

Conclusion

Curcumin has promising effects on the lipid profile and glycemic status of T2DM patients and might be a therapeutic option for T2DM patients with mixed dyslipidemia.

• Limitations were the small number of included studies, mostly with small sample sizes. In some studies, treatment duration was short (<2 months) and may be insufficient to see a difference in some metabolic parameters.
• The reduction of FBG and HbA1c after treatment with curcumin suggested that it improved the glycemic metabolism in the T2DM patients studied.
• Studies have shown that curcumin could promote insulin release through inducing β-cell electrical activity and lower serum glucose level via decreasing the production of hepatic glucose and increasing glucose uptake. While changes of LDL-c and HDL-c was not statistically significant, the authors note the effect of curcumin on LDL-c/HDL-c and its potential clinical significance could not be neglected.
• The reduction of dyslipidemia by curcumin supplementation could improve the glucose metabolic status of T2DM patients, and multiple molecular targets including PPAR-c, cholesteryl ester transfer protein, and lipoprotein lipase contribute to the beneficial effects of curcumin.

• While significant heterogeneity was found in pooled analyses of TG, LDL-c, FBG, and Hb1Ac, a random-effects model revealed that trial duration, curcumin dosage, and other therapy may contribute to the variation in pooled effects, and these aspects could be discussed in future studies.
• The study found that a higher dose of curcumin was more powerful in reducing plasma TG and FBG concentrations, but further large-scale multicenter RCTs are required to confirm the clinical improvement of curcumin.