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Insulin

Question
A doubt about insulopenia was expressed concerning a child a little over 4 years old following an OGTT (oral glucose tolerance test) one year ago. It was concluded that it has glucose intolerance without diagnosis of diabetes to date.
Would the risk of diabetes be decreased if that child received a small dose of insulin every morning?
Should it be mandatory that blood sugar is measured before an insulin injection (regardless of dose)?
Is there any risk of insulin dependency? Is there a risk to take insulin too early in case diabetes would be diagnosed in a few months or years?
And finally, what about a possible oral treatment with repaglinide for example?
We thank you in advance for your answers.
Answer
Hello
The onset of diabetes in a patient with cystic fibrosis is the direct result of the disease that causes progressive fibrosis of the pancreas and consequently disruption and destruction of the islets of Langerhans that secrete insulin. This cystic fibrosis related diabetes is linked primarily to a defect of the insulin secretion.

The development of abnormal glucose tolerance in CF is very progressive. Glucose intolerance precedes by many years the onset of diabetes. Diabetes is exceptional before the age of 10 years.

At the stage of glucose intolerance, insulin treatment is usually not indicated, but may be proposed in patients with very severe respiratory insufficiency and significant malnutrition. The onset of diabetes can be delayed by dietary measures: It is recommended to avoid the absorption of carbohydrates alone, especially those with high glycemic index (sweets, candies, sodas) and to take them at the end of the meal. Furthermore, we must insist on varied meals containing systematically fat and protein, which increases calorie intake and slows the absorption of carbohydrates.

Cystic fibrosis related diabetes is usually asymptomatic and is only diagnosed after a routine search by OGTT. In cystic fibrosis, when diabetes is discovered with an OGTT, blood fasting glucose and blood glucose before meals remain normal for a very long time while blood glucose after meals (2 hours after the start of the meal) increases.

The currently recommended treatment for cystic fibrosis related diabetes is insulin because it allows both to control blood glucose levels and maintain a good weight. When insulin therapy is prescribed, it is sufficient to start to monitor blood glucose after meals to adjust the insulin dose. After a period of development of diabetes, fasting blood glucose and blood glucose before meals increase requiring their control to adjust insulin doses. The insulin dose is calculated based on these results but also on the amount of carbohydrates to be ingested. When treatment is initiated, regular monitoring of blood glucose are desirable.

There is no risk of insulin dependence per se, but when diabetes is installed, the body needs insulin. These requirements increase in case of respiratory infections. When the patient gets older, insulin doses become more important because the pancreas is less functional.

Repaglinide, which stimulates the secretion of insulin from the islets of Langerhans, is sometimes prescribed in the early stages of diabetes in cystic fibrosis when the patient remains in good condition and shows no weight loss or respiratory deterioration. It precedes by a few months to several years the need for insulin prescription. There is so far no large studies comparing the effects of treatment with insulin and repaglinide in cystic fibrosis related diabetes.

Best regards.
Dr Dominique HUBERT and Pr Laurence KESSLER

04.06.2016