Research shows citrus and grape compounds may protect against type 2 diabetes

Nov 2 2025

A new Italian study reveals that a daily blend of citrus and grape extracts with chromium can normalize blood sugar and improve cholesterol faster than diet alone, offering new hope for millions living with prediabetes.

Study: Impact of a food supplement containing Citrus limon L. Osbeck and Vitis vinifera L. extracts, hesperidin and chromium in combination with an isocaloric diet on glucose and lipid metabolism in subjects with impaired fasting blood glucose: a single-center, controlled, randomized, parallel-arm, double-blind clinical trial. Image Credit: nnattalli / Shutterstock

In a recent study published in the journal Frontiers in Nutrition, researchers investigated whether a novel food supplement could improve metabolic health in people with impaired fasting glucose (IFG). The study comprised a single-center, six-month, randomized, double-blind, placebo-controlled trial wherein 62 subjects with IFG were placed on a healthy diet. Half of the included participants received a supplement containing citrus and red grape extracts, hesperidin, and chromium (250 µg chromium and 560 mg total flavonoids per day).

Supplementation Restores Normal Blood Glucose Levels

Study findings revealed that supplementation reduced fasting blood glucose from 114 to 94 mg/dL within 6 months and achieved normal fasting levels by 3 months, while also improving low-density lipoprotein (LDL-C, “bad”) cholesterol, high-density lipoprotein (HDL-C, “good”) cholesterol, and triglycerides. In contrast, the placebo group showed a small reduction in fasting blood glucose (113 to 107 mg/dL), but it remained in the prediabetes range, with no meaningful lipid improvements and a rise in triglycerides, suggesting that this multi-ingredient approach may serve as a valuable strategy for managing prediabetes.

Prediabetes, Growing Health and Metabolic Challenge

Impaired fasting glucose (IFG), commonly known as prediabetes, is a rapidly growing global health issue. It is characterized by blood sugar levels higher than normal but not yet diagnostic of type 2 diabetes (T2D), and is strongly linked to cardiovascular disease (CVD) risk. Although prediabetes is often reversible through a healthy diet and exercise, adherence is low, and lifestyle measures alone are frequently insufficient. This has led researchers to explore nutritional supplements that can complement traditional lifestyle interventions and deliver measurable metabolic benefits.

Study Design and Research Objectives

This randomized, double-blind, placebo-controlled clinical trial aimed to determine whether a specific blend of ingredients, chromium, hesperidin, and extracts from lemon and red grapes, could improve glucose metabolism and lipid balance in individuals with IFG. Fasting blood glucose served as the primary outcome, with HbA1c, insulin, HOMA-IR, and a full lipid panel as secondary endpoints.

Participant Details and Treatment Protocol

The study enrolled 62 Italian adults (ages 18–75) diagnosed with IFG (fasting blood glucose levels of 100–125 mg/dL). Participants were randomly assigned to either the supplement or placebo group. The treatment group received two tablets daily (after lunch and dinner) for six months, while both groups followed an isocaloric DASH (Dietary Approaches to Stop Hypertension) diet. Use of additional glucose- or lipid-affecting supplements or drugs was prohibited.

Supplement Formula and Dietary Control

The supplement provided 250 µg of chromium and 560 mg of flavonoids derived from Citrus limon (lemon), Vitis vinifera (red grape), and Citrus sinensis (orange). Participants received dietary counseling to maintain an isocaloric regimen. Blood samples were collected at baseline, three months, and six months to measure key biomarkers, including glucose, insulin, HbA1c, and lipid fractions.

Primary and Secondary Outcomes

The primary endpoint was the effect of supplementation on fasting blood glucose (FBG), while secondary endpoints included HbA1c, insulin resistance (HOMA-IR), and lipid markers (total cholesterol, HDL-C, LDL-C, and triglycerides). Statistical analyses incorporated demographic and medical history corrections to ensure robust comparisons between groups.

Results, Improved Glucose and Lipid Control

The supplement group achieved a significant reduction in fasting glucose (114 to 94 mg/dL) compared with the placebo group (113 to 107 mg/dL). HbA1c decreased significantly only in the supplement group, while insulin and HOMA-IR showed no treatment effect. Lipid outcomes were also favorable, with LDL-C decreasing from 114 to 73 mg/dL, HDL-C increasing from 38 to 56 mg/dL, and triglycerides declining significantly (p = 0.011). Conversely, triglyceride levels increased in the placebo group (p = 0.0012). Aspartate transaminase (AST), alanine transaminase (ALT), and creatinine levels indicated excellent tolerability.

Clinical Significance, Limitations, and Future Outlook

This study supports the therapeutic potential of a citrus and grape extract supplement with hesperidin and chromium for managing prediabetes. Within six months, the formulation normalized blood glucose and improved lipid balance, suggesting strong cardiovascular benefits. However, limitations include the single-center design, restriction to participants with a BMI <30, and lack of post-trial follow-up, which may affect generalizability. Further multicenter human trials are recommended to validate the durability and scalability of the results.