This study evaluates the efficacy of D-Chiro-Inositol (DCI) as an add-on therapy to metformin in improving insulin resistance, measured by the HOMA index, in people with overweight or obesity and type 2 diabetes mellitus (T2DM). Secondary outcomes include glycemic variability, indirect calorimetry, respiratory quotient, and other metabolic parameters.

The DIACHIRO trial is a randomized, double-blind, crossover clinical trial assessing the impact of DCI combined with metformin versus metformin plus placebo on insulin resistance in people with overweight or obesity and T2DM. The primary outcome is the change in the HOMA index. Secondary outcomes include glycemic variability parameters (e.g., time in range), oxidative stress markers, indirect calorimetry, respiratory quotient, and HbA1c levels. Participants are monitored using Flash Glucose Monitoring (FGM) systems.

Inclusion Criteria:

1. Diagnosis of type 2 diabetes mellitus.
2. Age between 18-75 years.
3. BMI ≥25 kg/m².
4. HbA1c < 9%.
5. Stable dose of metformin for at least three months prior to enrollment.

Exclusion Criteria:

1. Use of antidiabetic drugs other than metformin within three months prior to enrollment.
2. History of ketoacidosis or severe hypoglycemia within six months prior to enrollment.
3. Significant renal or hepatic impairment (eGFR <60 mL/min/1.73 m²; ALT/AST >2× ULN).
4. Pregnancy or lactation.