In Poland like in other countries we observe an increasing number of diabetes mellitus cases with about half of the patients in whom the disease remains undiagnosed. Therefore it seems necessary to improve early diagnoses and prevention of the disease. The aim of the study was to assess the efficiency of a 3-month non-pharmacological intervention based on diet and increased physical activity in patients with newly diagnosed diabetes type 2 (diagnosis based on oral glucose tolerance test (OGTT), WHO 1999). We investigated 37 newly diagnosed diabetic type 2 patients, 16 men (aged 52.4 +/- 5.4) and 21 women (aged 51.0 +/- 5.7). Anthropometric and biochemical measurements were performed before and after intervention. Two-kilometres Walking Test with an intermediate estimation of VO2max and fitness index (FI) was performed before and after intervention. Total abdominal fat volume (measured from diaphragm to pubis): visceral fat volume (VFV) and subcutaneous fat volume (SFV) (mm3) were assessed according to the standard protocol of NMR abdominal examination. Patients completed 12 weeks of supervised intervention focused on weight reduction, increase of physical activity, changes of nutritional habits. Students t-test, Mann-Whitney test and Spearman's correlation were used for statistical analysis. In women the average weight reduction was 4.7 kg (5.8% of initial body weight), whereas in men 5.9 kg (5.9% of initial body weight). In women VO2 max increased from 23.7 +/- 6.4 to 24.9 +/- 4.8 (ns), and fitness index increased from 78.7 +/- 11.7 to 83 +/- 14.7 (ns). In men VO2 max increased from 22.5 +/- 6.7 to 26.6 +/- 8.6 (ns) and fitness index increased from 55.1 +/- 12.5 to 64.8 +/- 13.7 (p < 0.05). In women the level of fasting glycaemia decreased from 6.47 +/- 1.2 to 4.84 mmol/l +/- 0.6 (p < 0.01) and the level of glycaemia at 120 minutes of OGTT decreased from 13.2 +/- 2.5 to 6.76 +/- 2.7 mmol/l (p < 0.01). The decrease of plasma glucose was accompanied by the decrease of fasting insulin from 19.2 +/- 15.5 to 8.53 +/- 93.2 uj/ml (p < 0.01) and in 120 minutes of OGTT from 148.8 +/- 86.2 to 58.4 +/- 41.0 uj/ml (p < 0.01). In men the level of fasting glycaemia decreased from 8.63 +/- 2.0 to 7.07 mmol/l +/- 2.4 (p < 0.05) and the level of glycaemia at 120 minutes of OGTT decreased from 15.76 +/- 3.2 do 9.3 +/- 5.7 mmol/l (p < 0.01). The decrease of plasma glucose was accompanied by the decrease of fasting insulin from 21.99 +/- 12.6 to 10.1 (3.8 uj/ml (p < 0.05) and at 120 minutes of DGTT from 81.5 +/- 52.7 do 41.6 +/- 21.0 uj/ml (p < 0.05). After the intervention 45% of the patients (57% of women and 31% of men) were non-diabetic (correct OGTT). In men visceral fat volume (VFV) was greater than in women (7642.6 +/- 1774.6 and 4789.9 +/- 1242.0 mm3 respectively (p < 0.01). Subcutaneous fat volume (SFV) was smaller in men than in women (7116.5 +/- 2048.5), in men and 10533.9 +/- 3478.3 respectively (p < 0.01). In women and men a strong (p < 0.01) correlation between waist circumference and visceral fat volume (VFV) (r = 0.573 (p < 0.01) and r = 0.833 (p < 0.01) respectively) and subcutaneous fat volume (SFV) (r = 0.900 (p < 0.01) and r = 0.790 (p < 0.01) respectively) was found. The results of the study confirm that in newly diagnosed diabetic type 2 patients body weight reduction and increased physical activity result in the improvement of biochemical indices. In about one half of patients the early phase of the disease might be reversible due to weight reduction and increased physical activity. The non-pharmacological intervention should be the first intervention undertaken in newly diagnosed diabetic type 2 patients.