Advances in the treatment of cystic fibrosis in children have increased the life expectancy of patients. In addition, in patients with cystic fibrosis in the respective centers, the state of carbohydrate metabolism is examined annually . All this led to a more than twofold increase in the incidence of diabetes among such patients. Diabetes mellitus is found in almost 25% of adolescents with cystic fibrosis. The treatment of these patients differs sharply from the treatment of patients with type 1 diabetes mellitus (DM 1) and type 2 diabetes mellitus (DM 2), since the pathophysiology of these conditions is different, and in addition, cystic fibrosis imposes significant restrictions on nutrition and drug therapy.
Patients are characterized by low body weight and insulin deficiency . However, like DM 2, the disease develops imperceptibly and ketoacidosis rarely occurs. Autoantibodies to islet cells are absent. The dependence of microvascular complications on the duration of diabetes mellitus, blood glucose control and lung damage is unknown. Obviously, there is no need to fear macrovascular complications in these cases.
The development and course of diabetes in cystic fibrosis depends on a number of factors:
1) frequent acute and chronic infections periodically change the degree of insulin resistance ;
2) infectious diseases and lung damage increase energy needs;
3) malnutrition shortens the lives of patients;
4) insufficiency of exocrine pancreatic function , despite the use of enzymes, leads to disruption of absorption processes in the intestine;
5) the absorption of nutrients is disturbed due to changes in the transit time of food through the digestive tract;
6) there are impaired liver function ;
7) poor health , gastroesophageal reflux , slow emptying of the stomach, bowel obstruction , increased breathing and psychological factors disrupt appetite and cause vomiting ;
8) in connection with exacerbations of the disease, food consumption on different days is different;
9) the secretion of insulin and glucagon is impaired .
The exocrine part of the pancreas is replaced by connective and adipose tissue; many pancreatic islets are destroyed, and in the remaining, the number of beta cells and alpha cells , as well as cells secreting the pancreatic polypeptide, decreases . The response of insulin , glucagon and pancreatic polypeptide to various stimulants is impaired. It is assumed that insulin resistance plays a role in the pathogenesis of diabetes mellitus in cystic fibrosis , especially during acute infectious diseases.
In Denmark, an oral glucose tolerance test was performed in all patients with cystic fibrosis. In patients younger than 10 years, diabetes was not detected, but it was found in 12% of patients aged 10-19 years and in 48% of patients older than 20 years. According to the Midwestern Medical Center (USA), where patients with cystic fibrosis are given an oral test annually, only 50% of children and approximately 25% of adult patients have normal glucose tolerance. Diabetes mellitus was found in 9% of children, 26% of adolescents and 35% of patients aged 20-29 years. Fasting hyperglycemia was detected in 30% of patients with diabetes mellitus. Glucocorticoid therapy was accompanied by a temporary or permanent increase in fasting blood glucose in 3% of children, 11% of adolescents, and 15% of adult patients.
Concomitant hyperglycemia metabolic disorders are usually mild, and if necessary, insulin therapy is sufficient to enter a relatively small dose of the hormone. A progressive deterioration in islet cell function can lead to the development of ketoacidosis . Insulin is used in the same way as with diabetes 1 , but the symptoms of the underlying disease prevent diet therapy.