Diabetes

Question

I have several questions concerning CF related diabetes. How does it occur in CF? How is the treatment? When should the treatment be started? Are there differences between CF related diabetes and diabetes? When in a CF related diabetes does one start a treatment with insulin?

Answer

The pancreas has 2 important functions: it produces and secretes pancreatic enzymes (read about it in the sections on enzymes) and it is also the site of insulin production. Insulin is a hormone, important for the uptake of sugars out of the blood into the tissues. All the tissues need glucose to produce energy so that the body can function. Sugars arrive in the blood via digestion of food in the intestine. Under normal circumstances exactly the right amount of insulin is being produced in the pancreas. But as patients with CF become older, the pancreas will have scars. As a consequence of this, the insulin producing cells in the pancreas are partially destroyed, an insufficient amount of insulin is produced and insulin is released slower than usual. This will delay the uptake of sugars into the tissues so that too much sugars remain in the blood.
The risk to CF Related Diabetes (=CFRD) begins around the age of puberty and increases with the patient’s age. About 1/3rd of all CF patients will develop CFRD during their lifetime.
CFRD differs from diabetes type I. In diabetes type I there is no longer any production of insulin, whereas in CFRD a sort of baseline amount of insulin is still being produced. That is why the classical symptoms of diabetes (lots of urine and drinking a lot) are rarely present in patients with CFRD. In CFRD more general complaints occur such as being tired, worsening of lung condition or weight loss.
The diagnosis of CFRD is made with a sugar tolerance test called Oral Glucose Tolerance Test (=OGTT). After fasting, the patient drinks a concentrated sugar solution. The sugar blood level is determined before and 2 hours after drinking the solution. The diagnosis of CFRD is made when the fasting blood sugar level is > 126 mg/dL or when the glucose level at 2 hours is above 200 mg/dL.
Whether or not treatment needs to be started is not a black and white answer. It depends on the individual patient and it s being decided by the doctor and the diabetic team. The treatment consists of administration of insulin via injections. Depending on the severity of CFRD the doctor may choose one injection of long acting insulin or 4 injections with a combination of long acting and short acting insulins. The short acting insulins are always administered just before a main meal. It is important that CFRD is well treated. Optimal glucose control will make sure the patient feels better, has more energy, is more resistant towards infection and has a better lung disease course. Poor glucose control worsens the prognosis for patients with CF.

Best regards,

I.Claes, K De Boeck

05.08.2011