Potential Protective Effect of Cocoa Flavanols in Type 2 Diabetes: A Systematic Literature Review of Human Studies

Díaz López Cristina*

Objective: This systematic review aims to critically evaluate existing human epidemiological and intervention studies investigating the potential protective effects of cocoa flavanols against Type 2 Diabetes Mellitus (T2DM).

Methods: A systematic literature search was conducted using PubMed, Science Direct, and Web of Science databases, covering the period of the last 15 years. Keywords used included “cocoa,” “flavan-3-ols,” “type 2 diabetes,” “interventional studies,” and “epidemiological studies.” Inclusion criteria involved original research articles examining cocoa flavanol intake and its effects on glycemic control, insulin sensitivity, lipid profile, endothelial function, and oxidative stress biomarkers in humans. Exclusion criteria included non-human studies, reviews, and studies lacking defined outcomes, and articles without clearly defined outcomes were excluded. PRISMA guidelines were followed for the review protocol.

Main findings: Eighteen studies were included: eight epidemiological and ten intervention studies. Epidemiological studies generally demonstrated an inverse association between moderate, regular cocoa consumption and risk of developing T2DM, particularly evident in populations with normal weight and healthy lifestyle practices. Intervention studies yielded mixed results: improvements in insulin sensitivity, endothelial function, lipid profiles, and oxidative stress were observed in some studies, especially with chronic, high-dose cocoa flavanol intake. However, other studies reported no significant effects, possibly due to methodological heterogeneity, short durations, and variability in flavanol dosages.

Conclusion: Although evidence from human studies suggests cocoa flavanols may have beneficial effects in managing or preventing T2DM, findings are not entirely consistent across studies. Well-controlled, long-term clinical trials with standardized flavanol dosages and clearly defined populations are necessary to firmly establish the clinical utility of cocoa flavanols for diabetes prevention or management.

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Published on: Jul 1, 2025 Pages: 1-13

Full Text PDF Full Text HTML DOI: 10.17352/ojpp.000026
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