**9. The challenges of CFRD**

The distinct glucose profile typically seen in CFRD presents clear challenges not only for establishing the diagnosis in the first place but also for managing the condition in general.

### **9.1. Dietary considerations**

The primary aim of nutritional management in relation to CFRD is the achievement of a normal nutritional status [3]. CFRD has different and conflicting dietary recommendations from that of type 1 or type 2 diabetes. CFRD patients have up to 150% the calorific requirements of other diabetic patients and require a diet containing both high fat and protein levels.

Patients with CF require regular snacks in between meals in order to meet their increased metabolic requirements and often resort to consuming foodstuff that is high in refined sugars – such as so called 'energy drinks' – in order to maintain their weight, especially as it obviates the need to medicate with enzyme supplements [75].

Ingestion of products that contain even modest quantities of highly refined sugar can not only cause glucose excursions but may also precipitate a reactive hypoglycaemic episode – a phenomenon that can be seen during 7-15% of diagnostic OGTTs [24, 76].

The use of a diet rich in carbohydrates that have a low glycaemic index (GI) is encouraged in type 2 diabetics both to aid blood glucose control and weight reduction, however little robust evidence exists of benefit from a similar approach in a CFRD population and there are concerns that low GI diets might lead to inappropriate weight loss in this group [72].

Recommendations from American researchers have suggested that carbohydrate counting may have a role in CFRD [3] however in other countries this approach is reserved for T1DM alone, with the CF dietetic community in the United Kingdom favouring regular meals and snacks containing a mixture of both complex and refined carbohydrates be taken with or just after eating other foods [75]– an approach that anecdotally can reduce both the post-prandial glucose excursions as well as subsequent reactive hypoglycaemia occurring.

Dietary assessment is therefore an important part of the management of CFRD particularly to assess and modify refined sugar intake whilst ensuring overall calorific requirements and a healthy weight are maintained.

### **9.2. Exercise**

**•** Clinical history - number of admissions with reasons

**•** Hypoglycaemia – identify cause and optimise treatment

**•** Foot examination - pedal pulses, sensory and vibration check.

**•** Frequency of distal intestinal obstruction syndrome (DIOS)

**•** Urea and electrolytes, creatinine clearance (selected cases)

Additionally, annual screening is an opportunity to identify educational gaps and discuss how

The distinct glucose profile typically seen in CFRD presents clear challenges not only for establishing the diagnosis in the first place but also for managing the condition in general.

The primary aim of nutritional management in relation to CFRD is the achievement of a normal nutritional status [3]. CFRD has different and conflicting dietary recommendations from that

**•** Full dietetic review - Meals, snacks, enzymes, supplements, feeds.

**•** Height, weight and BMI

100 Cystic Fibrosis in the Light of New Research

**•** Pulmonary function

**•** Alcohol and smoking

**•** Sexual dysfunction

**•** Insulin therapy

**•** Injection technique. **•** Insulin site check

**•** Psychosocial support

**•** HbA1c

**•** Lipid profile

**•** Home blood glucose monitoring.

**•** Urine sample for Microalbuminuria

**•** Retinopathy screening referral

**9. The challenges of CFRD**

**9.1. Dietary considerations**

the patient is coping with their CFRD.

**•** Blood pressure

**•** Exercise

Regular exercise forms an important cornerstone of the general management of CF and is widely advocated [46] although direct evidence that it specifically improves overall blood sugar control in CFRD is lacking [77] although there is an on-going trial exploring this currently [78] CFRD patients need to be aware of the risk of precipitating hypoglycaemia during exercise and should be educated about extra monitoring during times of exertion.

### **9.3. Liver disease**

CF affects all of the major organs in the body including the liver and the prevalence of CFRD is higher in patients who have liver disease [79]. As discussed previously significant liver disease may lead to a reduction in hepatic glycogen stores, exacerbating the risk of sympto‐ matic hypoglycaemia developing and potentially reducing the response to exogenous glucagon used to treat such episodes. In addition, although it may be difficult to quantify, CFliver disease could lead to subtle impairments of hepatic insulin secretion and catabolism which may contribute to the overall dysglycaemia suffered by this group [79].

### **9.4. Hypoglycaemia**

As mentioned elsewhere in this chapter hypoglycaemia is not uncommon in CFRD [24]. Furthermore, it has been demonstrated that hypoglycaemia awareness is also impaired as a result of frequent subclinical hypoglycaemic episodes and a diminished glucagon response [32]. Therefore, careful consideration must be given to when blood sugar monitoring is carried out as well as the timing, type and amount of insulin used for treatment.

### **9.5. Corticosteroids**

Oral corticosteroids (e.g. prednisolone) are frequently used during pulmonary exacerbations in CF, and the concomitant elevation in blood glucose may necessitate a change in diabetes management in these patients. Patients may also require increased supervision and treatment during times of infection where blood glucose levels often fluctuate rapidly. There is evidence that CF patients with normoglycaemia exhibit diabetic glucose tolerance during pulmonary exacerbations [80]. This is likely to be due to the stress of infection and inflammation that unmasks the early alterations in glucose homeostasis [81]. Additionally, when infection subsides and patients stop corticosteroids, blood glucose can dramatically drop causing hypoglycaemia and careful support and advice is required during this time.
