Carbohydrates Flashcards
Is it possible that someone:
A) has glucosuria at a serum glucose concentration of 5 mmol/l?
B) Does not have glucosuria at a serum glucose concentration of 15 mmol/l?
A) Glucosuria without hyperglycemia can be caused by renal glucosuria This can happen in reduced uptake in the proximal tubules, e.g. Falconi syndrome. Also, with the use of SGLT2 inhibitors (90% of glucose are absorbed through these).
B) Hyperglycemia without glucosuria can be e cause of decreased GFR. Reduced filtration also means reduced glucose. Therefore the tubules have time to absorb all the glucose. At normal GFR the maximal amount of reabsorbed glucose without glucosuria is 10 mmol/l. In end-stage diabetic kidney the GFR can be reduced to 5-10 ml/min and they should be put on dialysis and kidney transplantation list.
15 year-old girl has been losing weight in spite of having a good appetite, and she feels tired lately. She has been admitted to the hospital for vomiting, being dizzy, and disoriented.
Laboratory findings: Urine glucose: strongly positive Ketone bodies: positive Blood glucose: 28.5 mmol/l Blood pH: 7.1 Serum K+: 5.4 mmol/l
What is your diagnosis, and what is to be done with her?
Blood glucose is way above 11 mmol/l and she has one classic symptoms of DM (loosing weight). She most likely has diabetes mellitus.
Blood pH is low and serum is positive for ketone bodies.
Her K+ levels are high because Na/K ATPase pumps need glucose to function, and right now the glucose cant enter cells. So K+ are staying extracellularly. However, total body K+ is decreasing even though the serum K+ is high.
She has diabetes type 1 with diabetic ketoacidosis. Confirm diagnosis by looking for ICA, IAA or glutamic acid decarboxylase antibodies.
Treatment:
- Insulin
- IV hydration (saline)
- K+
- IV bicarbonate if necessary
Ketone bodies will ultimately be flushed out with urine. She was tired because the glucose couldn’t enter her cells (she was in a fasting state), dizziness because of dehydration, vomiting because of the acidosis.
GLUT2/3 can become dysfunctional with a fast glucose decline, so it must be done step-by-step. To fast rehydration can cause brain edema. K+ levels must be monitored to avoid hypokalemia when the Na/K ATPases begin working again. If it is difficult to normalise the pH, bicarbonate can be given.
A 56-year old man who used to be healthy complains of polyuria.
Laboratory findings:
Fasting blood glucose: 7.3 mmol/l
Fasting blood glucose a week later: 7.6 mmol/l
What is your diagnosis, what would you do with him?
Fasting blood glucose is over 7 mmol/l, which indicates diabetes mellitus. A second measurement was made a week later to ensure that this actually was fasting blood glucose. Since his blood glucose levels are over 7 mmol/l, the diagnosis of DM can be made. An oGTT should NOT be performed.
To determine wether or not it is DM type 1 or 2, antibodies (ICA, IAA, GADA) can be looked for. But becase of his age (DM 1 rarely appear after age 30) it is most likely DM type 2.
I would also check for metabolic syndrome, and arrange so that he also is tested for retinopathy, neuropathy, albuminuria and risk for CV disease (atherosclerosis).
It is also important to educate the patient of healthy lifestyle choices (food with low GI, exercise, quit smoking). If necessary, give oral anti glycemic drugs like metformin, SGLT2 and sulfonylurea.
A 60 year-old woman, weighing 90 kg.
Fasting blood glucose: 6.9 mmol/l.
No glucose, no ketone bodies in urine.
Results of oral glucose tolerance test:
Fasting: 6.4 mmol/l
2h value: 8.5 mmol/l
What is your diagnosis and what would you advise her to do?
A woman weighing 90 kg is most likely overweight, but by how much depends on her height.
Fasting blood glucose is almost 7 mmol/l, which would put her in the category of DM. During her oGTT the fasting glucose was decreased (maybe she didn’t fast for the first test?), however the 2h value puts her in the category of impaired fasting glucose (IFG).
I would advise this woman to make lifestyle changes (reduce body weight, eat food with low GI, exercise, quit smoking, inform about the consequences of DM) and also check if she has metabolic syndrome. Schedule a follow-up to measure blood glucose.
Laboratory findings of a person:
Fasting blood glucose: 6.2 mmol/l
Oral glucose tolerance test performed on another occasion:
Fasting value: 6.3 mmol/l
2h value: 6.5 mmol/l
What is the diagnosis, and what is the clinical significance of it?
Fasting glose taken on first occasion is elevated (should be below 5.5 mmol/l). It was still elevated when the oGTT was performed. 2h value of the oGTT was below 7.8 mmol/l, so it puts the patient in the impaired fasting glucose (IFG) category.
The clinical significance is that 20-25% of patients with IFG/IGT will develop DM type 2. This predispose to other problems like atherosclerosis and cardiovascular disease, nephropathy, neuropathy and retinopathy. People diagnosed with diabetes has higher mortality than healthy people.
What are your options to check the glucose metabolism of your diabetic patient to decide if the current treatment needs to be changed or not?
NEVER use oGTT on a diabetic patient!
- HbA1c (will tell the mean glucose level the last 2-3 months). It should be less than 7% for diabetic patients. Check 4 x a year, if it remains stable, 2 x year.
- Check for nephropathy, retinopathy, neuropathy and atherosclerosis.
- Home glucose test kit (let the patient take note of the values and bing to you).
- Check for metabolic syndrome as well
A diabetic patient treated with insulin has a fasting blood glucose concentration of 6.4 mmol/l. No glucose was detected on the morning of examination (?) (EDIT: in urine maybe?). The Hb-A1c level is 10% (normal value 3-6%).
Do you think the control of glucose concentration was acceptable in the last 1-2 months?
No, the HbA1c value reflects the mean glucose level the last 2-3 months. Maybe the patient have not been taking their medication regularly, but decided to take his medication right before the glucose measurement. Target level HBA1c for diabetic patients is 7%. In this case it is important to inform the patient of the consequences of high blood glucose.
It could also be because the medication are not working well, and maybe an extra medication should be given (SGL2 and GLP-1).
A type 1 diabetic man has been eating very little for the last couple of days due to a febrile illness, so he decided to stop administering his insulin. He checked his blood glucose, because he felt worse and worse, and was surprised to see that it was more that 20 mmol/l. What is the explanation?
There is very little, if any, endogenous insulin production in people with type 1 diabetes. Even if the person is eating very little, he will need insulin for the glucose to enter cells. Also, insulin is needed to counteract gluconeogenesis. In its absence, the body produce lots of glucose. Febrile illness can also induce cortisol secretion, which will counteract insulin.
A diabetic man treated with insulin skipped his evening meal before going to bed, without any change in his insulin administration. He has been sweating a lot during the night and glucose has been detected in his urine in the morning. What is the explanation for this?
The man missed his evening meal, but administered insulin, causing hypoglycemia. Hypoglycemia induce adrenergic activation (sympathetic system) giving symptoms like shivering and sweating. Sympathetic activation because of hypoglycemia activates hormones anatagonising insulin, like glucagon and cortisol. These hormones elevates the glucose levels.
This is called the Somogyi effect, and it not really a thing?
A man with type 1 diabetes is cooperating well with his physician, keeps his diet and insulin administration very precisely. He is an employee of a bank, and currently attends a team building training, a several-day-long survival tour causing significant physical exertion. The man, who is known for being revered, starts shouting and quarrelling with his coworkers, then he begins to sweat, quiver and develop cramps.
What do you think is the explanation of his behaviour?
This survival tour is most likely very physically challenging and is requiring a lot of extra energy from this man. Most likely he uses more glucose than normal because of the increased physical activity, and maybe they are not given sufficient with food.
The man is becoming hypoglycemic and his sympathetic system is activated giving him symptoms like sweating, quivering, and cramps. Also his CNS is affected, making him irritable, change personality and maybe confused. Neuroglycopenia will give symptoms of headaches, more expressed tiredness, problems speaking and coma.
Glucose 4 transportes are translocated to the cell membrane with exercise.
The man must be given glucose per os. The blood sugar should be checked after 15 minutes and if still low, more glucose should be given. Glucagon would not be effective in such a setting as he might not have glycogen stored because of strenuous exercise.
A woman was admitted to the hospital with the complaint of recurrent seizures.
Her fasting glucose level is 2.7 mmol/l
What can cause these symptoms? What tests would you perform to establish the diagnosis?
The woman has a fasting glucose of 2.7 mmol/l. Normal fasting glucose should not be below 3 mmol/l.
Here is it important to understand what is causing the hypoglycemia, and what is causing the seizures and wether or not they are related.
- Is the woman using medications that can cause hypoglycemia (sulfonylureas) or insulin, and are they over administered?
- Is she on a strict diet?
- Does she have insulinoma (rare), Addison’s disease, hypothyroidism?
- Is she abusing alcohol? Gluconeogenesis goes down with ingestion of ethanol.
- Does she have fever or sepsis?
Tests:
- C-peptide (who much insulin is produced? Is the insulin endogenous or exogenous?)
- Imaging (insulinoma)
- ACTH-stimulation test (will the adrenals respond or not?)
