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. 2020 Jan 27;9(2):346. doi: 10.3390/jcm9020346

Table 2.

Summary of the Completed Clinical Trials with Flavonoids for the Treatment of DM.

Objective to Study Treatment Duration Results PMID
Diabetic Nephropathy Renoprotective effect of milk thistle extract on T2D patients with macroalbuminuria. n = 30; 3 × 140 mg silymarin
n = 30; Placebo
3 months Significant decrease in UACR levels, urinary TNF-α and urinary and serum MDA in the silymarin group. 22770926
NCT01003236
Effect of silymarin on glycemic control and body mass index in T2D patients with insulin resistance and poor glycemic control with oral hypoglycemic agents n = 18; 200 mg silymarin + 10 mg Glibenclamide
n = 21; Placebo + 10mg Glibenclamide
4 months Silymarin treatment significantly reduced fasting and postprandial plasma glucose, HbA1c levels and body mass index. 17887949
Effects silymarin administration on the glycemic state in T2D patients. n = 25; 3 × 200 mg silymarin
n = 26; Placebo
4 months Decreased significantly FBG, HbA1c, total cholesterol, LDL, triglyceride, GOT and GPT after treatment with silymarin. 17072885
Safety and effect of green tea (epigallocatechin gallate, EGCG) in patients with DN. n = 24; ACEi/ARBs + 800 mg EGCG
n = 23; ACEi/ARBs + Placebo
3 months Treatment with green tea extract reduced UACR by 41%. 27320846
NCT01923597
Effects of isolated soy protein consumption on urinary albumin excretion and blood lipid profile in early stages of DN. n = 14; 0.5 g/kg/day of the dietary protein was provided as either isolated soy protein 2 × 8 weeks Soy protein consumption reduced UACR levels by 9,55%. 15284369
Efficacy of curcumin for blocking DN development in T2D patients (short time). n = 14; 500 mg curcumin 1 month Curcumin attenuated microalbuminuria and reduced plasma MDA and LPS levels content. Maintaining gut barrier integrity and function. 25875220
Diabetic Retinopathy Effects of pycnogenol in early stages of DR. n = 24; 150 mg pycnogenol
n = 22; Placebo
2 months Visual improvement was subjectively perceived by 18 of 24 patients in the pycnogenol group. Significant improvement visual acuity from baseline. 19916788
Evaluate long-term follow-up of the orally administered combination of flavonoids for treatment of diabetic cystoid macular edema without macular thickening. n = 35; 300 mg Diosmin,
15 mg C. asiatica
160 mg Melilotus
n = 35; Placebo
3 years Retinal sensitivity reduced in control group only from month 6 until month 36. In the treatment group, a greater retinal sensitivity was present at month 12, 24, and 36. 23844756
Determine the relationship between dietary flavonoid-rich fruit and vegetable consumption on DM-related biomarkers and DR. Data from 381 participants with DM from the NHANES 2003–2006. - Greater high-flavonoid fruit and vegetable consumption was associated with lower levels of CRP, HbA1c and glucose, with reducing the odds of having diabetic retinopathy by 30%. 25055729
Efficacy of anti-oxidant dietary supplementation reducing the ROS levels in patients with non-proliferative DR. n = 34; 50 mg pycnogenol, 30 mg Vit. E, 20 mg CoQ
n = 34; Placebo
6 M In the group receiving antioxidant therapy the levels of free oxygen radicals and retinal thickness were significantly reduced over three times. Conversely, in the control group a significant increase was observed. 25686055
Diabetic Neuropathy Efficacy and safety of QR-333 (quercetin, ascorbyl palmitate and vitamin D3) in the treatment of diabetic neuropathy. n = 23; three topical applications QR-333
n = 11; Placebo
1 M QR-333 produced significant relief of some symptoms of diabetic neuropathy and was safe and well tolerated. 16112498
NCT16112498
Cardiovascular complications Effect of flavanol-rich chocolate in patients with hypertension. n = 20; Cross-over
100 mg Dark Chocolate
(88 mg flavanols)
90 mg flavanol-free White Chocolate
15 d per treatment Dark chocolate decreased blood pressure and serum LDL cholesterol, improved FMD, and ameliorated insulin sensitivity in hypertensive patients. 16027246
Evaluate whether regular ingestion of an unsweetened, strongly defatted and flavanol-rich cocoa powder might improve BP and glucose and lipid metabolism in stably treated T2D subjects. n = 17; Five × 0.5 g cocoa powder capsules
n = 18; Placebo
3 M Daily intake of 2.5 g of flavanol-rich, unsweetened and strongly defatted cocoa powder does not affect BP, glucose and lipid metabolism in stably-treated patients with T2D and hypertension in a fasting state. 30301127
Effect of dietary flavonoids on CVD risk in postmenopausal women with T2D on established statin and hypoglycemic therapy. n = 59; 27 g flavonoid-enriched chocolate
n= 59; Placebo
12 M Improvement in insulin sensitivity was observed. Reductions in total cholesterol, HDL-cholesterol ratio and LDL cholesterol. Estimated 10 year total coronary heart disease risk was attenuated after flavonoid intervention. 22250063
NCT00677599
Effect of combined isoflavone and flavan-3-ol intake on vascular function in postmenopausal women with T2D. The flavonoid intervention did not significantly change the intima-media thickness of the common carotid artery, augmentation index, or BP, but pulse pressure variability improved.
Effect of oral Hesperidin supplementation in hemodynamic changes in T2D patients. n = 32; 500 mg Hesperidin
n = 32; Placebo
1.5 M Significant difference in mean percent change of SBP, diastolic blood pressure, mean arterial BP, serum TAC, and inflammatory markers between Hesperidin and control groups. 29468764
Association between the intake of total polyphenols and polyphenol classes with the major CV risk factors in a T2D population. TOSCA.IT study. n = 2573 people with T2D 10 years A diet characterized by a higher intake of total polyphenols was associated with a better cardiovascular risk factors profile and a lower grade of subclinical inflammation. 27890487
NCT00700856