Background: Dietary phytochemical index (DPI) has introduced as an inexpensive method for quantifying the phytochemicals in foods. For the first time, this study was conducted to investigate the relationship between DPI and the risk of prediabetes. Methods: Three hundred participants were assigned to 150 prediabetics (cases) and 150 healthy (controls) groups. Anthropometric values, fasting blood glucose, and 2‑ h oral glucose tolerance test (OGTT) were measured. The DPI was calculated based on data collected from 168‑ item validated food frequency questionnaire. Results: The sex‑ specific energy‑ adjusted DPI was inversely related to fasting blood glucose (FBG) and OGTT (P < 0. 001). The odds ratio (OR) of prediabetes was assessed across sex‑ specific energy‑ adjusted DPI quartiles. After adjusting for body mass index, physical activity, education, dietary intake of energy, fiber, carbohydrate (% of energy), fat (% of energy), and protein (% of energy), the OR of prediabetes across the sex‑ specific energy‑ adjusted DPI quartiles decreased significantly (P‑ trend < 0. 001). Conclusions: We found that higher DPI score is related to lower prediabetes OR. This simple method may be used for the improvement of dietary intake to prevent prediabetes.