Question
A 38-year-old female develops moderate hyperglycemia during her first pregnancy and is diagnosed with gestational diabetes mellitus. Her glycemic status improves markedly after delivery. She says that her mother and younger sister both had “high blood sugars” during pregnancy. If this patient’s gestational hyperglycemia is genetically predisposed, this patient is most likely to have decreased activity in which of the following enzymes:
| A. |
Enolase
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| B. |
PDH
|
| C. |
Glucokinase
|
| D. |
LDH
|
Show Answer
|
Correct Answer � C
Explanation
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|
Anc. C. Glucokinase
Glucokinase serves as a major glucose-sensor for the beta cell. An increase in serum glucose leads to increased metabolism of glucose within the beta cells, ultimately leading to insulin secretion by the formation of ATP. The conversion of glucose to glucose-6- phosphate by glucokinase is crucial and rate limiting. Once metabolized to glucose-6-phosphate glucose is rapidly metabolized in the glycolytic and citric cycle. Glucokinase defects result in one of the types of maturity-onset diabetes. Inactivating mutations of the glucokinase gene lead to a decrease in the enzyme’s function, causing decrease in the metabolism of glucose, lesser ATP formation, and diminished insulin secretion.
