Cystic fibrosis-related diabetes (CFRD) affects up to 50% of adults over age 35 with cystic fibrosis (CF). CFRD is categorized as pancreatogenic or type 3c diabetes, and rarely complicated by diabetic ketoacidosis (DKA), particularly in the absence of co-existing type 1 diabetes. We present a patient with CFRD who developed in-hospital DKA due to inadequate glycemic control.
Methods : A 38 year-old male with CF post-bilateral lung transplant presented for fundoplication. He was diagnosed with CF at 5 months of age and developed CFRD in 2004. His home insulin regimen consisted of lantus 20 units daily and novolog 2 units per 15 grams of carbohydrate. Postoperative ileus led to decreased oral intake and inappropriate discontinuation of basal insulin. Endocrinology was subsequently consulted for progressively worsening hyperglycemia. On questioning, patient denied nausea, vomiting, abdominal pain, fever or chills. Family history was negative for diabetes or CF.
Results : Physical exam revealed a hemodynamically stable, well-appearing adult male with normal BMI of 21.9 kg/m2. Labs revealed hyperglycemia with blood glucose 449 mg/dL, elevated hemoglobin A1c 9.2% (4.3 – 5.6%), beta-hydroxybutyrate 0.93 (<0.28 mmol/L) and anion gap 22 (9-18 mmol/L), with evidence of ketonuria. Screening for type 1 diabetes revealed no evidence of islet cell, insulin or glutamic acid decarboxylase-65 antibodies. Intravenous insulin infusion and fluids were initiated for treatment of DKA, and transitioned to basal-bolus insulin therapy following resolution of ketoacidosis.
Discussion : CFRD results from progressive loss of islet cell mass and insulin resistance in CF patients who experience further glycemic dysfunction from frequent infections and glucocorticoid therapy. Only a few case reports of DKA in CFRD patients is available in literature, and some patients were subsequently diagnosed with type 1 diabetes. Therefore, the Clinical Care Guidelines for CFRD by the American Diabetes Association recommends screening for diabetes autoantibodies in any CF patient with DKA.
Conclusion : The lack of ketoacidosis in CFDR may be in part attributed to incomplete insulin deficiency and concomitant glucagon deficiency from underlying exocrine pancreatic insufficiency. Our patient with CFDR developed in-hospital DKA after inappropriate discontinuation of basal insulin in the absence of underlying type 1 diabetes. Although at low risk for DKA, we emphasize the importance of adequate glycemic control and vigilant monitoring against development of ketoacidosis in patients with CFRD.
Cleveland Heights, Ohio
Endocrine Fellow at Cleveland Clinic
Staff Endocrinologist, Cleveland Clinic