This study aimed to evaluate the phytochemicals and total antioxidant capacity in the diets of individuals with type 2 diabetes and assess their relationship with glycemic parameters, as well as certain biochemical parameters and Fibroblast growth factor 21 (FGF21), which is an inflammatory marker. The study was conducted on a total of 80 individuals, including 40 patients with overweight or obesity (Body Mass Index (BMI) > 25 kg/m²) with type 2 diabetes aged between 18 and 64, and 40 healthy controls (BMI between 18.5-35 kg/m²). The individuals were followed for 12 weeks with an appropriate diet. Biochemical parameters, anthropometric measurements, and dietary intake records were monitored at specific intervals throughout the study. The phytochemical index and total antioxidant capacity of the individuals' diets were measured, and FGF21 was examined in the serum.

Individuals were divided into two groups: type 2 diabetes and control. Individuals with type 2 diabetes were followed for 12 weeks with an appropriate diet specific to their condition, and necessary measurements were taken at the beginning, 4th week, and 12th week. No dietary intervention was made for the control group, and necessary measurements were taken at the beginning and 12th week. At the control points, biochemical parameters, serum samples, anthropometric measurements (body composition, weight, height, waist circumference, hip circumference), 24-hour dietary intake record, and 24-hour physical activity record were evaluated. In the experimental group, dietary intake was recorded at the beginning (week 0), 4th week, and 12th week. The dietary intake of the control group was examined at week 0 and week 12.

The "Phytochemical Index" method was used to calculate the total phytochemical intake from the diet. The total antioxidant capacity of the diet was calculated using data obtained from dietary intake records based on Ferric Reducing Ability of Plasma (FRAP), Oxygen Radical Absorbance Capacity (ORAC), Trolox Equivalent Antioxidant Capacity (TEAC), and Total Reactive Antioxidant Potential (TRAP) methods. Additionally, physical activity was determined using a recording method. Body compositions at all three control points will be determined using the bioelectrical impedance method, and waist and hip circumference measurements were taken using a non-stretchable tape measure. Routine biochemical parameters for the type 2 diabetic group (fasting blood glucose, serum lipids, HbA1c) were obtained from the records. Serum samples collected after a 10-12 hour fasting period at the beginning and 12th week were analyzed for Fibroblast growth factor 21 (FGF21) using suitable kits.

Inclusion Criteria:

• For intervention group: type 2 diabetes diagnosis
• For control group: healthy individuals
• Aged between 19 and 64
• With a body mass index over 25 kg/m²

Exclusion Criteria:

• Pregnancy
• Type 1 diabetes
• Cancer
• Chronic kidney disease
• Chronic liver disease
• Other chronic inflammatory diseases
• Individuals with HbA1c levels above 9%
• Individuals using short or medium-acting or mixed (medium+short) insulin
• Individuals with any condition that hinders physical activity
• Individuals following any weight loss diet