January 01, 2011
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Position statement, guidelines address cystic fibrosis-related diabetes

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The Pediatric Endocrine Society has backed a position statement from the American Diabetes Association and clinical practice guidelines produced by the Cystic Fibrosis Foundation that tackle the problem of cystic fibrosis-related diabetes.

The statement, which appeared in Diabetes Care, represents the first time that experts from three major organizations came together to create guidelines, according to Antoinette Moran, MD, member of the Cystic Fibrosis-Related Diabetes Committee.

“There is still great heterogeneity in the United States and around the world in how [cystic fibrosis-related diabetes] is defined, diagnosed and managed,” Moran, also of the division of pediatric endocrinology at the University of Minnesota in Minneapolis, told Endocrine Today. “The endocrine community has been less familiar with the management of these patients than the [cystic fibrosis] community. The goal of the statement is to guide consistent and appropriate clinical practice based on the most current knowledge.”

The statement is the third of its kind, Moran explained, and was born from a desire to update previous recommendations.

“The last position statement was written about 10 years ago at a time when there were not much data available to guide decisions,” she said. “New data over the last decade have resulted in increased understanding of how best to diagnose and treat [cystic fibrosis-related diabetes].”

Moran also noted that the guidelines will be reviewed every 3 years and will undergo updates if a sufficient amount of new research is available.

Special screening considerations

“In [cystic fibrosis], the nutritional and pulmonary consequences of diabetes are of greater concern,” the guidelines committee wrote. “[Cystic fibrosis-related diabetes] is associated with weight loss, protein catabolism, lung function decline, and increased mortality, and thus regular screening is warranted.”

Such screening should occur annually, with the initial visit occurring at age 10 years. In this population, HbA1c is not an adequate indicator of diabetes, according to the guidelines committee, and the oral glucose tolerance test should be used instead.

Self-monitoring of blood glucose levels is insufficient to diagnose cystic fibrosis-related diabetes. Nevertheless, it may be beneficial for cystic fibrosis patients with acute pulmonary exacerbation and during continuous drip enteral feedings, the committee wrote. In both situations, however, hyperglycemia indicated by SMBG must be confirmed by laboratory testing.

According to the committee, cystic fibrosis-related diabetes can be diagnosed in patients with acute illness if FPG levels of at least 126 mg/dL or 2-hour postprandial plasma glucose levels of at least 200 mg/dL persist for more than 48 hours. Similarly, mid- or postfeeding plasma glucose levels exceeding 200 mg/dL on 2 separate days indicate a diagnosis of cystic fibrosis-related diabetes in patients on enteral continuous drip feedings.

Additionally, pregnant women should be screened before and after delivery, and those undergoing transplantation should also be tested before and after the procedure.

Management issues

Patients with the disease should receive insulin therapy, but oral diabetes agents prove less effective for treatment, the committee wrote. SMBG should be performed at least three times daily, and patients should follow the ADA recommendations for glucose goals.

Likewise, guidelines for blood pressure measurement and monitoring for microvascular complications should be in line with ADA recommendations, according to the committee. Patients with hypertension or microvascular complications, however, do not require sodium or protein restrictions. Annual lipid profiles are also recommended for patients with pancreatic exocrine sufficiency or with certain other risk factors, such as obesity or family history of coronary artery disease.

Physicians should also consider the emotional toll that the additional diagnosis places on patients with cystic fibrosis, and a multidisciplinary team and ongoing diabetes education should be provided, the committee wrote.

“[Cystic fibrosis-related diabetes] is very different from either type 1 or type 2 diabetes and requires a unique approach specifically tailored to this population,” Moran said. “In particular, the association of insulin insufficiency and hyperglycemia with early death from inflammatory pulmonary disease is a unique and significant aspect of [cystic fibrosis-related diabetes].”

For more information:

Disclosure: Dr. Moran has no direct financial interest in any of the products mentioned in this article nor is she a paid consultant for any companies mentioned.

PERSPECTIVE

As improved care of pulmonary disease in cystic fibrosis has allowed survival into and beyond middle age, endocrinologists are becoming aware that cystic fibrosis-related diabetes is a common problem. The new clinical care guidelines published in December 2010’s Diabetes Care represent good practical support for clinicians, patients, and their families. Most, but not all, of the recommendations reflect consensus opinion from an expert panel, due to the paucity of clinical trials in cystic fibrosis-related diabetes. Highlights from these guidelines that strike me as most important include 1) recommendation to screen patients with cystic fibrosis annually beginning at age 10, using standard 2-hour oral glucose tolerance testing as the “gold standard” for diagnosis (and using existing cut-offs of 126 mg/dl fasting and > 200 mg/dl at the 2-hour time point), and 2) treating patients with at least mealtime bolus insulin therapy, to promote adequate nutrition and prevent excessive weight loss, and premature decline in pulmonary function. Oral antihyperglycemic therapy for cystic fibrosis-related diabetes is strongly discouraged in the guidelines. Using postprandial glycemic values on the OGTT as the basis for diagnosis and treatment recognizes unique pathophysiology of cystic fibrosis-related diabetes, in that insulin reserve, while depleted and inadequate to normalize postprandial blood glucose, is often adequate to prevent fasting hyperglycemia. The relevant caveat regarding treatment is that patients with normal fasting glucose may not require basal insulin therapy.

– Stephen A. Brietzke, MD
Endocrine Today Editorial Board Member

Disclosure: Dr. Brietzke has no direct financial interest in any products mentioned in this article nor is he a paid consultant for any companies mentioned.

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