Original Paper

Evaluation of the Pituitary Function with Insulin Tolerance (Hypoglycaemia) Testing: Are There Any Differences Using Insulin Lispro Compared to Regular Insulin?
Kevin C.J. Yuen^a, Rakesh Amin^b, Marie B. Cook^a, Sharon A. Rhoads^a, David M. Cook<sup>a

a</sup>Department of Endocrinology, Oregon Health and Science University, Portland, Oreg., USA;
^bDepartment of Endocrinology, Royal Manchester Children's Hospital, Manchester, UK

Address of Corresponding Author

Horm Res 2008;69:233-239 (DOI: 10.1159/000113024)

  Key Words

• Insulin tolerance test
• Hypoglycaemia
• Insulin lispro
• Regular insulin

  Abstract

Background/Aim: The insulin tolerance test (ITT) remains the gold standard for evaluating the pituitary function, but has potential risks when hypoglycaemia is induced. There are scarce data using short-acting insulin analogs for ITTs. This pilot study compares the effects of insulin lispro (LPI) with regular insulin (RGI) during an ITT. Methods: Patients with suspected hypopituitarism (n = 103) randomly received either LPI (n = 51) or RGI (n = 52). Results: All patients reported signs and symptoms when hypoglycaemia was induced. In the LPI group, hypoglycaemia occurred sooner (23.6 ± 1.6 vs. 28.3 ± 1.4 min, p < 0.05), and duration of hypoglycaemia (25.0 ± 1.7 vs. 31.9 ± 1.9 min, p < 0.05) and time for blood glucose levels to return to a 'safe' level (>3.3 mmol/l; 56.5 ± 2.3 vs. 76.0 ± 2.1 min, p < 0.001) were shorter as compared with the RGI group. No differences in peak growth hormone and cortisol levels were observed between the two groups. Conclusions: Our data suggest that despite inducing similar symptomatology, LPI exerted a quicker onset and a shorter duration of hypoglycaemia as compared with RGI. Thus, using LPI might reduce the potential risks associated with an ITT by shortening the hypoglycaemic phase of the test.

Copyright © 2008 S. Karger AG, Basel

  Author Contacts

Dr. Kevin C.J. Yuen
Department of Endocrinology, Oregon Health and Science University
3181 SW Sam Jackson Park Road, mailcode L607
Portland, OR 97239-3098 (USA)
Tel. +1 503 494 0175, Fax +1 503 494 6990, E-Mail yuenk@ohsu.edu

  Article Information

Received: December 11, 2006
Accepted: June 7, 2007
Published online: January 21, 2008
Number of Print Pages : 7
Number of Figures : 1, Number of Tables : 2, Number of References : 36