LISBON – A single in-home test of urinary C-peptide creatinine ratio appears to differentiate type 1 diabetes from a genetic form of the disease – maturity-onset diabetes of youth.
The in-home test saves children and parents from the stress and inconvenience of a blood test, and discriminates maturity-onset diabetes of youth (MODY) from type 1 diabetes with 100% sensitivity and 85% specificity, Dr. Rachel Besser said at the annual meeting of the European Association for the Study of Diabetes.
"MODY is frequently misdiagnosed as type 1 diabetes in children, and inappropriately treated with insulin," said Dr. Besser of the Peninsula Medical School, Exeter (England). "This test is clinically useful even in patients with a very short duration of disease."
In addition to guiding treatment, the test can pinpoint which children should undergo genetic testing for MODY, she said.
The test is a simple kit designed to be administered after a normal, diabetic-healthy evening meal. "We ask the children to empty their bladders before eating, have a dinner that contains healthy carbohydrates, and then take the test about 2 hours later."
Parents collect the urine at home and mail it to a laboratory, where the C-peptide creatinine ratio (UCPCR) is measured. A boric acid solution preserves the biomarker for up to 72 hours while en route to the lab.
Dr. Besser and her colleagues examined the test’s efficacy in 96 children who had been diagnosed with type 1 diabetes and 29 children who had confirmed MODY (10 with the HNF1A/4A subtype and 19 with the GCK subtype). All of the children had a mean disease duration of about 3 years. The mean age of the type 1 patients was 13 years; the MODY children were slightly older, at a mean of 14 years.
The test differentiated the two disorders quite well, Dr. Besser said. UCPCR was significantly lower in the type 1 samples than in the MODY samples (median 0.05 vs. 3.41 nmol/mmol).
Using a cutoff of at least 1.4 nmol/mmol, the test correctly discriminated MODY from type 1 diabetes with 100% sensitivity and 85% specificity. Fourteen of the patients diagnosed with type 1 diabetes met the cutoff point of at least 1.4 nmol/mmol.
The test is obviously far better than the method of calculation by family history, Dr. Besser added. "That only correctly identifies about 50% of these patients. There are also new, different mutations that we are discovering all the time," which are not familial.
Dr. Besser had no financial disclosures.