Lifestyle intervention in individuals with normal versus impaired glucose tolerance


  • Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, Germany (S. Schäfer, K. Kantartzis, F. Machicao, A. Fritsche, H.-U. Häring, N. Stefan); Section on Experimental Radiology, University of Tübingen, Germany (J. Machann, F. Schick); Department of Internal Medicine, Division of Rehabilitative, Preventive and Activity–Sports Medicine, University of Tübingen, Germany (C. Venter, A. Niess).

  • S. Schäfer and K. Kantartzis contributed equally to this work.

Norbert Stefan, MD, Department of Internal Medicine, Otfried-Müller-Str. 10, D-72076 Tübingen, Germany. Tel.: +49 7071 2980390; fax: +49 7071 295974; e-mail:


Background  Lifestyle intervention is effective in the prevention of type 2 diabetes in individuals with impaired glucose tolerance (IGT). It is currently unknown whether it has beneficial effects on metabolism to a similar extent, in individuals with normal glucose tolerance (NGT) compared to individuals with IGT.

Materials and methods  Data from 181 subjects (133 with NGT and at risk for type 2 diabetes and 48 with IGT) who participated in the Tuebingen Lifestyle Intervention Program with increase in physical activity and decrease in caloric intake were included into this study. Body fat distribution was quantified by whole-body magnetic resonance (MR) tomography and liver fat and intramyocellular fat by 1H-MR spectroscopy. Insulin sensitivity was estimated from an oral glucose tolerance test (OGTT).

Results  After 9 ± 2 months of follow-up, the diagnosis of IGT was reversed in 24 out of 48 individuals. Only 14 out of 133 participants with NGT developed IGT. Body weight decreased in both groups by 3% (both P < 0·0001). Two-hour glucose concentrations during an OGTT decreased in individuals with IGT (–14%, P < 0·0001) but not with NGT (+2%, P = 0·66). Insulin sensitivity increased both in individuals with IGT (+9%, P = 0·04) and NGT (+17%, P < 0·0001). Visceral fat (–8%, P = 0·006), liver fat (–28%, P < 0·0001) and intramyocellular fat (–15%, P = 0·006) decreased in participants with IGT. In participants with NGT these changes were significant for visceral fat (–16%, P < 0·0001) and liver fat (–35%, P < 0·0001).

Conclusions  Moderate weight loss under a lifestyle intervention with reduction in total, visceral and ectopic fat and increase in insulin sensitivity improves glucose tolerance in individuals with IGT but not with NGT. In individuals with NGT, the beneficial effects of a lifestyle intervention on fat distribution and insulin sensitivity possibly prevent future deterioration in glucose tolerance.