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Horm Metab Res 2006; 38(2): 106-111
DOI: 10.1055/s-2006-925128
Original Clinical
© Georg Thieme Verlag KG Stuttgart · New York

Metformin Increases Insulin Sensitivity and Plasma β-endorphin in Human Subjects

H.-Y.  Ou1, 2 , J.-T.  Cheng3 , E.  H.  Yu1 , T.-J.  Wu1
  • 1The Division of Endocrinology and Metabolism, Department of Internal Medicine, Tainan, Taiwan
  • 2Institute of Clinical Medicine, College of Medicine, Tainan, Taiwan
  • 3Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
Further Information

Publication History

Received 23 May 2005

Accepted after revision 25 October 2005

Publication Date:
08 March 2006 (online)

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Abstract

Metformin has been widely used in clinical type 2 diabetes treatment and prevention. The present study was designed to explore the effect on people with a sedentary lifestyle at therapeutic doses. Twenty-two physically-inactive volunteers with normal glucose tolerance were studied. Escalating doses of metformin in low-dose (250 mg), intermediate-dose (500 mg), and high-dose (750 mg) treatment three times per day were administrated into each subject for a three-week treatment period. Fasting plasma glucose, A1C, HOMA-IR for insulin resistance, lipid profile, and plasma β-endorphin-like immunoreactivity (BER) were measured before treatment and weekly at the end of each dosing period. Metformin significantly reduced fasting plasma glucose and HOMA-IR in healthy humans after receiving this treatment at therapeutic doses including low-dose (5 %, 17 %), intermediate-dose (6 %, 25 %) and high-dose treatment (6 %, 21 %). Plasma BER was also increased from 135.46 ± 61.73 pg/ml to 137.52 ± 66.11 pg/ml by low-dosing (p = 0.39), to 139.17 ± 64.08 pg/ml by intermediate-dosing (p = 0.32), and to 149.59 ± 63.32 pg/ml by high-dosing (p < 0.05). Also, serum cholesterol decreased significantly using metformin at therapeutic doses including low-dose (4 %), intermediate-dose (8 %) and high-dose treatment (7 %). However, metformin failed to modify levels of serum HDL-cholesterol and C-reactive protein (CRP) in healthy subjects. Also, the reduction of serum cholesterol by metformin did not correlate to the increase in insulin sensitivity. In conclusion, metformin causes a significant parallel increase in insulin sensitivity and plasma β-endorphin level in human subjects.

Keywords

Metformin - insulin sensitivity - β-endorphin - physical inactivity

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T. J. Wu, MD

Department of Internal Medicine · College of Medicine · National Cheng Kung University

138, Sheng-Li Rd. · Tainan · Taiwan 70101

Phone: +886(6)235-3535 ext 5387

Fax: +886(6)302-8130 ·

Email: djwu@mail.ncku.edu.tw