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Endocrine Abstracts (2010) 24 OC3.3

BSPED2010 Oral Communications Oral Communications 3 (3 abstracts)

Are there practical alternatives to the inpatient mixed meal tolerance test for patients with Type 1 diabetes?

R E J Besser 1 , A G Jones 1 , T J McDonald 2 , B M Shields 1 , B A Knight 1 & A T Hattersley 1


1Peninsula NIHR Clinical Research Facility, Peninsula Medical School, Exeter Devon, UK; 2Department of Clinical Biochemistry, Royal Devon & Exeter NHS Foundation Trust, Exeter Devon, UK.


Introduction: Stimulated serum C-peptide (sCP) during a mixed meal tolerance test (MMTT) is the gold standard measure of endogenous insulin secretion in Type 1 diabetes (T1D). However invasiveness of sampling, the need to discontinue insulin prior to testing and rapid processing of samples limits its widespread use, particularly in children. Practical alternatives would increase utility.

Aims: To assess if in a MMTT: 1.It is necessary to omit insulin. 2. Fasting C-peptide can replace stimulated C-peptide measurement. 3. Urinary C-peptide is an alternative to serum C-peptide.

Methods: We studied 51 T1D patients (age diagnosis median (IQR)18(13–24y), diabetes duration (0.2–65.9y). We performed a standard MMTT without insulin and a MMTT with the subject’s normal morning insulin. We measured sCP at 0min and 90min, and urine C-peptide creatinine ratio (UCPCR) at 0 min (second morning void) and 120min, following a liquid mixed meal (Ensure High Protein).

Results: (1) 90minute sCP values were only slightly lower in the MMTT with insulin compared to the standard MMTT without insulin (mean sCP 0.28 v 0.35 nmol/l P=0.01) despite a much lower glucose increment (4.1 v 9.8 mmol/l, P<0.0001). 90min sCP was highly correlated between the two tests (r=0.97, 95%CI 0.95, 0.98). (2) Fasting sCP was well correlated with 90min sCP (r=0.89, 95% CI 0.81, 0.94). (3) Second void fasting UCPCR and 120min UCPCR were both well correlated with 90min sCP (fasting UCPCR: r=0.83, 95% CI 0.72, 0.90; 120min UCPCR: r=0.87, 95% CI: 0.78, 0.92).

Conclusion: Omitting insulin during a mixed meal tolerance test may not be necessary. Measurement of fasting serum C-peptide and fasting or meal stimulated urinary C-peptide are other practical alternatives that may be useful in routine practice, avoiding the need for inpatient investigation.

Volume 24

38th Meeting of the British Society for Paediatric Endocrinology and Diabetes

British Society for Paediatric Endocrinology and Diabetes 

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