A 34-year-old woman with obesity presented to the endocrinology clinic with a 4-year history of progressively worsening skin lesions and a 3-month history of unintentional weight loss. Her body-mass index (the weight in kilograms divided by the square of the height in meters) was 30. Physical examination showed symmetric clusters of pink-yellow papules that merged into branching projections on the trunk, buttocks, and all four limbs. Laboratory studies showed a fasting triglyceride level of 6349 mg per deciliter (71.7 mmol per liter; reference value, <150 mg per deciliter [<1.7 mmol per liter]), a total cholesterol level of 760 mg per deciliter (19.7 mmol per liter; reference value, <200 mg per deciliter [<5.2 mmol per liter]), and a glycated hemoglobin level of 11.8% (reference range, 4.0 to 5.6). The thyrotropin level was normal. Biopsy of skin from the right calf revealed foamy macrophages, loose lipids, and fusiform fibroblast hyperplasia. A diagnosis of eruptive xanthomas due to severe hypertriglyceridemia in the context of untreated diabetes mellitus was made. Eruptive xanthomas are a sign of severe hypertriglyceridemia, a condition in which prompt intervention may prevent complications such as pancreatitis. A treatment regimen of a low-fat diet, fenofibrate, insulin, and oral diabetes agents was initiated. At follow-up 6 months after presentation, the eruptive xanthomas had resolved, but hyperpigmentation remained over the branching projections.