Candidiasis: This is the most common cause of vaginal itching in diabetic patients. Diabetes increases the risk of candidiasis due to higher glucose levels in the mucosal secretions, which facilitates the growth of Candida albicans.

Bacterial Vaginosis (BV): Although not as directly linked to diabetes as candidiasis, BV is a common cause of vaginal itching and discharge. The altered pH and microbial environment in diabetic patients might predispose them to BV.
Trichomoniasis: A sexually transmitted infection that can cause vaginal itching, discharge, and odor. While not specifically more common in diabetics, it remains a consideration in sexually active women.
Atrophic Vaginitis: Common in postmenopausal women, this condition can cause vaginal itching and dryness. Diabetes itself isn't a direct risk factor, but the condition should be considered, especially in older diabetic patients.

Lichen Sclerosus: A chronic inflammatory skin condition that can cause intense itching and is associated with an increased risk of vulvar cancer. Although rare, missing this diagnosis could lead to significant morbidity.
Vulvar Intraepithelial Neoplasia (VIN): A precancerous condition that can cause itching and should be considered to prevent progression to invasive cancer.
Herpes Simplex Virus (HSV): Genital herpes can cause severe itching, pain, and lesions. Given its potential for significant morbidity and transmission, it's crucial not to miss this diagnosis.

Desquamative Inflammatory Vaginitis (DIV): A rare condition characterized by vaginal inflammation and ulceration, leading to itching and discharge. Its exact cause is unknown, but it might be considered in cases where common causes have been ruled out.
Vulvar Dermatoses: Other rare skin conditions like lichen planus or psoriasis can affect the vulva, causing itching and discomfort. These are less common but should be considered in the differential diagnosis if initial treatments fail.