## 4 The Antidiabetic Effects of Dietary Phenolic Compounds: Preclinical and Clinical Evidence
\begin{table}
\begin{tabular}{l l l l l} \hline \hline \multicolumn{1}{l}{_In Vivo Approaches_} & & & \\ \hline
**Compound** & **Animal Model** & **Administration,** & **Molecular Mechanism** & **Refs** \\  & & **Concentration, and** & & \\  & & **Duration of the Treatment** & & \\ \hline Proanthocyanidins & Diet-induced & Daily oral gavage & Protection of the gut barrier & [133] \\ polymers & obese mice & 37 mg/kg & integrity: Increased number of & \\  & (C57 BL/6J) & 8 weeks & mucin-secreting globet cells & \\ \hline Curcumin & Rats fed standard chow & One oral dose by gavage & Enhanced glucose-induced & [134] \\  & (Sprague-Dawley) & 1.5 mg curcumin/kg & secretion of GLP-1 & \\  & & & through a GPR40/ & \\  & & 120-dependent mechanism & \\ \hline Coffee & Mice fed & One oral dose by gavage & Enhanced postprandial GLP-1 & [135] \\ polyphenol extract & standard chow & 0.6 g/kg & secretion coupled with a reduced & \\  & (C57 BL/6J mice) & & postprandial glycemia & \\ \hline Resveratrol & Diet-induced obese & Oral & Improved oral glucose & [19] \\  & mice and GLP-1R & Diet supplementation & tolerance through a GLP-1 & \\  & KO mice & with 60 mg/kg & receptor-dependent mechanism & \\  & (C57 Bl/6J) & & & \\ \hline Polyphenol-rich fruit & Diet-induced & Daily oral gavage & Resistance to developing obesity & [136] \\ extracts: _Myricaria dubia_ & obese mice & 200 mg/kg & due to changes in gut microbiota & \\  & (C57 Bl/6J) & 8 weeks & composition, especially & \\  & & & an increase in the abundance of & \\  & & & _Akkermansia muciniphilla_ & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Molecular mechanisms involved in the glucoregulatory effects of phenolic compounds. A focus on muscle, liver, and intestine. \begin{table}
\begin{tabular}{l l l l l} \hline \hline \multicolumn{1}{l}{**Clinical Evidence**} & & & \\ \hline
**Compound** & **Clinical Trial** & **Administration,** & **Evidence of Antidiabetic** & **Refs** \\  & & **Concentration, and** & **Effects** & \\  & & **Duration of the Treatment** & & \\ \hline Cranberry extract & Diet-induced & Daily oral gavage & Protective effect: & [124] \\ (phenolic acids, & obese mice & 200 mg/kg & Restoration of & \\ flavonoids, & (C57 Bl/6J) & 8 weeks & hepatic steatosis & \\ anthocyanins, and & & & Improved oral & \\ proanthocyanidins) & & & glucose tolerance & \\  & & & Normalized & \\  & & & insulin sensitivity & \\ \hline Aspalathin & ob/ob mice: & Oral & Protective effect: & [124] \\  & hyperphagic and & Supplementation & Reduced fasting glycemia & \\  & overweight & of 20\% casein diet with & Improved glucose tolerance & \\  & leptin-deficient type & 0.1\% aspalathin & & \\  & 2 diabetic mice & 5 weeks & & \\  & (C57 BL/6J) & & & \\ \hline Green tea & High-fat diet fed & Daily oral gavage & Protective effect: & [127] \\ phenolic compounds & Zucker fatty (ZF) rats & 200 mg/kg & Reduced weight gain, & \\  & & 8 weeks & visceral fat accumulation, & \\  & & & fasting serum glucose and & \\  & & & insulin, and amelioration of & \\  & & & the insulin resistance & \\ \hline Proanthocyanidins & Diet-induced & Daily oral gavage & Improved oral & [133] \\ polymers & obese mice & 37 mg/kg & glucose tolerance & \\  & (C57 BL/6J) & 8 weeks & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._