INS and vitamin D deficiency: Primary outcome:• Highly effective correction of vitamin D deficiency• Serum 25(OH)D increased from 19.2 ± 6.2 ng/mL to 30.9 ± 10.1 ng/mL (Glass’s Δ = 1.2)Glycemic outcome:• Minimal improvement in glycemic control (Glass’s Δ = 0.1 for HbA1c)Additional findings:• Higher insulin dose and elevated BMI were associated with lower postintervention vitamin D levels• A sedentary lifestyle was significantly correlated with higher HbA1c