Blood Glucose Levels

[sportsguy131]

A 10 year old boy goes to a physician complaining of polyuria (increased urinary volume and frequency) and weight loss. A blood test reveals elevated blood glucose. What would further tests more likely reveal?
A) low insulin
B) Low ACTH
C) Low glucagon
D) Low cortisol

The answer is A. But I don't understand this answer, Here is my reasoning: When a person has elevated blood glucose levels, the body tries to achieve homeostasis by increasing insulin in the blood and decreasing glucagon levels. So this person would have high levels of insulin in the blood. Is the question badly worded or my reasoning is wrong? Any help would be appreciated.

Thank You.

[biohazard]

The question depicts a classical case of the onset of type I diabetes mellitus. That means that due to the loss of insulin-producing pancreatic beta cells because of an autoimmune reaction the insulin levels are low in the blood. This impairs the intake of glucose to the cells and results in elevated glucose levels in the blood. This, in turn, causes the so-called osmotic diuresis where the kidneys "leak" water and glucose due to the effects of the increased osmotic pressure.

So, your reasoning would not work in this case, since the pancreas cannot increase the insulin output because it simply cannot produce enough of it.

[JackBean]

If the boy was healthy than increased glucose would lead to increased insulin. But he's sick and what condition will lead to high glucose? High or low level of insulin?
In other words insulin level is not consequence but reason for the glucose level.

[JorgeLobo]

I think the options identified speak to etiology rather than next test. Tho' there are insulin assays, wouldn't the likely next test be glucose tlerance test?

[biohazard]

I think the options identified speak to etiology rather than next test. Tho' there are insulin assays, wouldn't the likely next test be glucose tlerance test?

In clinical practice, yes. But since the original question gives us just those four tests, I guess we have to assume that the aim is to demonstrate the changes that happen in a diabetic body and not what would be done in the "real world" with patients that have these symptoms.

In other words, it sounds more like a human biology 101 question than some medicine-related course :wink: