A 46-year-old man visited an ophthalmologist because of recent episodes of blurry vision. In addition to examining the man’s eyes, the ophthalmologist took a medical history and assessed the patient’s overall health. The patient was 6 feet tall and weighed 265 pounds (BMI equal to 36 kg/m2). He had recently been experiencing “tingling” sensations in his hands and feet and was sleeping poorly because he was waking up several times during the night with a full bladder. He had also taken to carrying bottled water with him wherever he went, because he often felt very thirsty. He reported that he worked as a taxicab driver and rarely if ever had occasion to engage in much physical activity or exercise. The patient attributed the tingling sensations to “sitting in one position all day” and was convinced that his eye prob- lems were the natural result of aging. Examination of the eyes, however, revealed a greatly weakened accommodation reflex in both eyes. These signs and symptoms suggested to the ophthalmologist that the patient might have diabetes mellitus, and he therefore referred the patient to a physician at the diabetes unit of his local hospital. Guide Questions: What are the major functions of insulin, particularly with respect to its effects on plasma glucose?
Clinical Case Study: An Overweight Man with Tingling, Thirst, and Blurred Vision
A 46-year-old man visited an ophthalmologist because of recent episodes of blurry vision. In addition to examining the man’s eyes, the ophthalmologist took a medical history and assessed the patient’s overall health. The patient was 6 feet tall and weighed 265 pounds (BMI equal to 36 kg/m2). He had recently been experiencing “tingling” sensations in his hands and feet and was sleeping poorly because he was waking up several times during the night with a full bladder.
He had also taken to carrying bottled water with him wherever he went, because he often felt very thirsty. He reported that he worked as a taxicab driver and rarely if ever had occasion to engage in much physical activity or exercise. The patient attributed the tingling sensations to “sitting in one position all day” and was convinced that his eye prob- lems were the natural result of aging. Examination of the eyes, however, revealed a greatly weakened accommodation reflex in both eyes. These signs and symptoms suggested to the ophthalmologist that the patient might have diabetes mellitus, and he therefore referred the patient to a physician at the diabetes unit of his local hospital.
Guide Questions:
- What are the major functions of insulin, particularly with respect to its effects on plasma glucose?
- What is meant by target-cell hyporesponsiveness? Is it unique to insulin?
Clinical terms: diabetes mellitus, diabetic ketoacidosis, insulin resistance, sulfonylureas, type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM)
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