Objective: Lipohypertrophy (LH) is one of the most common treatment-related cutaneous complications of injectable therapies. Although the etiology of LH cannot be clarified, it may be due to the lipogenic effect of insulin or recurrent tissue trauma caused by injections. In this respect, we aimed to evaluate the relationship between vitamin D level and LH. Material and Methods: Patients with Type 2 diabetes mellitus aged 18 years or older, who were under insulin and/or exenatide treatment for at least one year were included in this study. The injection sites of the patients were examined by inspection and palpation method. Patients were catego-rized into two groups according to vitamin D levels as below and above 20 ng/mL. Results: A total of 140 patients, including 91 women and 49 men, aged between 20-78 years with a mean age of 54.53±13.89 were included in the study. LH was detected in 91 (65%) of 140 patients. This study de-monstrated that there was a significant relationship between gender and LH. Statistically, the frequency of LH was higher in female patients (p=0.001). Further, a relationship between vitamin D levels and LH was also observed (p=0.006). Conclusion: Besides calcium metabolism, the effects of vitamin D on lipogenesis are also known. Vitamin D inhibits the differentiation of pre-adipocytes to mature adipocytes. This is the first study showing the relationship between vitamin D and LH in our knowledge.