Primary amenorrhea signifies an underlying genetic or endocrine abnormality. Swyer Syndrome, or 46, XY Complete Gonadal Dysgenesis, represents a rare etiologic entity characterized by phenotypic femaleness despite a male karyotype, secondary to aberrant gonadal differentiation. The resultant streak gonads confer hypoestrogenism and heightened gonadal malignancy risk. This report describes an uncommon coexistence of Swyer Syndrome and Type 1 Diabetes Mellitus (DM) in a young adult female.

A 31-year-old Filipino female presented to the outpatient clinic for evaluation of primary amenorrhea. She denied any family history of infertility, delayed puberty, or ambiguous genitalia. Her past medical history was remarkable for Type 1 Diabetes Mellitus, diagnosed at 22 years of age. At that time, laboratory results demonstrated marked hyperglycemia, with fasting blood glucose of 279 mg/dL and glycated hemoglobin (HbA1c) of 12.5%. Low serum C-peptide level of 0.11 nmol/L confirmed absolute insulin deficiency, consistent with Type 1 DM. She was commenced on insulin therapy and achieved improved metabolic control with regular follow-up. Amenorrhea was not previously reported due to sociocultural stigma, financial limitations, and restricted healthcare access.

Physical examination revealed a phenotypic female with normal external genitalia. Breast and pubic hair development were consistent with Tanner stage 2, while axillary hair was absent, indicating delayed secondary sexual maturation. Hormonal evaluation showed hypergonadotropic hypogonadism, with elevated follicle-stimulating hormone (33.90 mIU/mL) and luteinizing hormone (12.93 mIU/mL) levels, and low estradiol (10.57 pg/mL), suggestive of primary gonadal failure. Pelvic ultrasonography demonstrated hypoplastic uterus (4.6 × 2.3 × 1.6 cm), thin endometrium (0.2 cm), and a small cervix (1.4 × 1.2 cm), with non-visualization of the ovaries. Pelvic magnetic resonance imaging confirmed these findings, revealing a small uterus (2.2 × 3 × 0.7 cm), bilateral streak gonads, and a rudimentary vaginal canal. Chromosomal analysis established a 46, XY karyotype, confirming Complete Gonadal Dysgenesis (Swyer Syndrome). The patient was counseled regarding the heightened risk of gonadal malignancy and was advised to undergo prophylactic gonadectomy followed by hormone replacement therapy. However, she refused surgical management owing to cultural reservations and personal hesitation.

This case illustrates the intricate interplay between Swyer Syndrome and Type 1 DM, emphasizing the need for heightened clinical vigilance. Early identification of primary amenorrhea and delayed puberty facilitates timely intervention. A coordinated multidisciplinary approach remains essential to reduce gonadal malignancy risk, ensure appropriate hormonal management, and enhance overall reproductive and psychosocial well-being.