Watching for the Development of CF-Related Diabetes, and Helping to Prevent It

Studies have shown that 15-20% of CF patients, almost all pancreatic insufficient, will develop CF-Related Diabetes (CFRD). CFRD is not completely like Type I or Type II diabetes, because no insulin resistance is involved and biomarkers may not be the same. It is the fibrosizing of the pancreas in CF that leads to a severe decrease in the production of insulin. Furthermore, CF persons may become transiently diabetic when undergoing a pulmonary exacerbation.

This matters because CF persons who develop CFRD have more severe CF and a shorter life expectancy. Transition to CFRD starts early--the first biomarkers may become evident as young as age 8, and onset of abnormal glucose processing is typically 10-12 years of age.

CF persons and their families must be vigilant: a 60 minute OGTT test is the "gold standard" as of this writing, but Continuous Glucose Monitoring is actually the better test. Baseline levels may be normal, but levels 60 minutes after a meal may become quite abnormal. Furthermore, glucoce monitoring should be performed whenever the CF person is treated for a pulmonary exacerbation.

In addition, if you are only interested in ruling out CFRD, then the Hb1Ac test, using a lower cut-off of a reading ≥5.8 (% (mmol/mol)) to identify a strong enough probability of actual CFRD that follow-up testing should be done, should work fine.  If one reading is high, a second reading should be taken before going on to follow-up testing (which would be the OGTT).

If you are interested in "impaired glucose tolerance," which "may or may not" indicate progression to CFRD, then you would have to do an OGTT.  But values would have to be taken not just at baseline and 2 hours, but also at 1 hour.  It is that 1 hour value that tells you whether the CF person is subject to "glycemic excursions" which just means a very high reading indicating some troubling impairment.  Again, if the first test is abnormal, there should be a second test before pronouncing that there is in fact impaired glucose tolerance.

And this is complicated by the fact that while CFRD patients should definitely be put on insulin, there is no recommended therapeutic regimen for impaired glucose tolerance in CF.  Furthermore, while some CF persons with impaired glucose tolerance go on to develop CFRD, a lot don't--and some even revert to normal glucose tolerance status.

The treatment for CFRD is insulin. In fact, giving insulin even when full-blown CFRD has not yet come to fruition can forestall that eventuality and also rescue BMI.

However, there are some nutritionally related things that CF families might consider. First and foremost is to substitute high glycemic index foods with lower glycemic index foods. Say yes to gravy and no to candy. Avoid soda pop and sugary cereals. Get those calories in, but do it in a lower glycemic manner.

Exercise can also help. All CF persons should be exercising, for its positive benefits are immense.

Other nutritional possibilities include the addition of some chromium picolinate to the daily regimen, which aids in the processing of glucose.

While some scientists belive there are companion alleles or genes that predispose certain CF individuals to develop CFRD, it is also true that there is a role for being proactive and vigilant about the development of CFRD.