The purpose of this study is to better understand the interactions between the innate immune system, in particular eosinophils, their secreted cytokines (interleukin-4), and metabolism in human health and disease states such as obesity and insulin resistance.

Patients with a body mass index (BMI) less than 30 kg/m2 and a history of atopic dermatitis on long-term (greater than 6 months) treatment with dupilumab. Researchers will compare in vivo evaluations of insulin sensitivity in subjects on dupilumab vs subjects matched for similar weight and BMI, with atopic dermatitis, but without dupilumab therapy (phototherapy).

Inclusion Criteria:

• Ability to sign informed consent form.
• Body mass index (BMI), 22-29 kg/m^2.
• Diagnosis of Atopic Dermatitis treated with dupilumab for longer than 6 months.
• Diagnosis of Atopic Dermatitis treated with topical steroids or phototherapy.

Exclusion Criteria:

• Any prescription for systemic glucocorticoid, immunosuppressant, antidiabetic medications in the past 6 months.
• Evidence of diabetes mellitus.
• Morning Cortisol < 5 mg/dl (collected before 10.30 am).
• Presence of acute illness.
• Low hemoglobin or hematocrit.
• Current participation in a weight-loss regimen, with a weight loss > 10% total body weight in the last 6 months).
• Smoking history in the last 6 months (tobacco, nicotine-containing products including e-cigarettes).
• Pregnant or breastfeeding.
• Personal history of gastric bypass surgery.
• Previous participation in a clinical trial with an investigational product in the past 30 days, or 5 half-lives, or twice the duration of the biological effect of the investigational drug (whichever is longest).
• Exposed to more than 4 new chemical entities within 12 months before study enrollment.
• Any other condition or event considered exclusionary by the PI and the study physician.