CASE STUDY B Diabetes Mellitus Type 2 Mr. F. was diagnosed with Type 2 diabetes
ID: 243313 • Letter: C
Question
CASE STUDY B Diabetes Mellitus Type 2 Mr. F. was diagnosed with Type 2 diabetes mellitus at age 46 At that time, he was overweight, enjoyed foods with high car- bohydrate and fat content, and led a sedentary life. His family history indicated that his mother and his brother had diabetes. Weight loss, appropriate diet, and exercise were recommended to reduce blood glucose levels. 1. List the factors contributing to diabetes mellitus in this case. At age 50, Mr. F. noticed that his vision was cloudy, particularly in one eye. Cataracts were removed from both eyes 2. Describe a cataract and explain how diabetes promotes cataract formation. 3. Glyburide (DiaBeta) was prescribed at this time. Describe the action of this drug. At age 56, a blister developed on the heel of one foot, which did not heal. An ulcer formed and persisted. Finally the foot was placed in a cast for 13 weeks to promote healing. 4. Explain several factors contributing to the delayed healing in Mr. F 5. Why was it necessary in this case, to remove the cast and replace it each week? Peripheral neuropathy with total loss of sensory function had developed in both feet. Motor function was not directly affected. Orthopedic shoes were ordered and arrangements made for a podiatrist to provide regular foot care.Explanation / Answer
Diabetes mellitus
1.Factors contributing diabetes mellitus in this case is family history, overweight or obesity, no control over food habits, high carbohydrate and fat diet, sedentary life style.
2.Cataract is defined as the clouding of the lens of the eye which leads to decreased vision.
The enzyme aldose reductase (AR) catalyzes the reduction of glucose to sorbitol through the polyol pathway, a process linked to the development of diabetic cataract. Extensive research has focused on the central role of the AR pathway as the initiating factor in diabetic cataract formation.
It has been shown that the intracellular accumulation of sorbitol leads to osmotic changes resulting in hydropic lens fibers that degenerate and form sugar cataracts . In the lens, sorbitol is produced faster than it is converted to fructose by the enzyme sorbitol dehydrogenase. In addition, the polar character of sorbitol prevents its intracellular removal through diffusion. The increased accumulation of sorbitol creates a hyperosmotic effect that results in an infusion of fluid to countervail the osmotic gradient. Animal studies have shown that the intracellular accumulation of polyols leads to a collapse and liquefaction of lens fibers, which ultimately results in the formation of lens opacities . These findings have led to the “Osmotic Hypothesis” of sugar cataract formation, emphasizing that the intracellular increase of fluid in response to AR-mediated accumulation of polyols results in lens swelling associated with complex biochemical changes ultimately leading to cataract formation .
3.Glyburide or diabeta is prescribed for this patient
action of the drug:
The drug works by binding to and inhibiting the ATP-sensitive potassium channels (KATP) inhibitory regulatory subunit sulfonylurea receptor 1 (SUR1) ,in pancreatic beta cells. This inhibition causes cell membrane depolarization, opening voltage-dependent calcium channels. This results in an increase in intracellular calcium in the beta cell and subsequent stimulation of insulin release.
After a cerebral ischemic insult, the blood–brain barrier is broken and glibenclamide can reach the central nervous system. Glibenclamide has been shown to bind more efficiently to the ischemic hemisphere.Moreover, under ischemic conditions SUR1, the regulatory subunit of the KATP- and the NCCa-ATP-channels, is expressed in neurons, astrocytes, oligodendrocytes, endothelial cells and by reactive microglia.
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