THE EFFECT OF RESTRICTING ENERGY-INTAKE ON DIABETES IN PSAMMOMYS-OBESUS

The aim of this paper was to determine whether restricting energy inta ke would reduce the elevated levels of glucose, insulin, cholesterol a nd triglyceride in diabetic Psammomys obesus (sand rat). Between 11 an d 12 weeks of age Psammomys obesus were divided into three groups base d on blood glucose and plasma insulin levels in the fed ad libitum sta te; group 1 was normoglycemic (4.4 +/- 0.3 mM) and normoinsulinemic (0 .46 +/- 0.04 ng/ml), group 2 was normoglycemic (5.0 +/- 0.3 mM) and hy perinsulinemic (3.58 +/- 0.62 ng/ml) and group 3 was hyperglycemic (11 .2 +/- 1.2 mM) and hyperinsulinemic (6.23 +/- 0.73 ng/ml). Energy inta ke was restricted to 67% of normal for 2 weeks before ad libitum feedi ng was resumed for a further 2 weeks. Animals in group 3 developed the most abnormalities when compared to group 1 including increased level s of food intake (16.3 +/- 0.5 vs 14.2 +/- 0.5 g/day, P < 0.05), body weight (192 +/- 5 vs 162 +/- 4 g, P < 0.05), triglycerides (1.5 +/- 0. 2 vs 0.96 +/- 0.08 mM, P < 0.05), and cholesterol (2.8 +/- 0.2 vs 2.1 +/- 0.1 mM, P < 0.05). In group 3, food restriction was effective in r educing glucose levels (but not insulin) both during and following the restriction period respectively (11.2 +/- 1.2 vs 4.6 +/- 0.5, and 5.9 +/- 1.3, mM, P < 0.05). In group 2, energy restriction had similar ef fects by reducing glucose levels (5.03 +/- 0.26 vs 4.2 +/- 0.13 and 3. 99 +/- 0.19, mM, baseline vs restriction and post restriction, P < 0.0 5) and insulin levels (3.57 +/- 0.62 vs 0.96 +/- 0.27 and 1.50 +/- 0.3 9, ng/ml, baseline vs restriction and post restriction, P < 0.05). Cho lesterol and triglyceride levels were also reduced in group 2 and grou p 3 during the restriction period (P < 0.05). In addition, glucose and insulin responses to the meal tolerance test were also reduced for gr oup 2 and group 3 during the restriction period. In group 1, glucose, insulin and triglyceride levels were not significantly reduced during the restriction period. Furthermore, energy restriction did not signif icantly reduce body weight in any group suggesting that the restrictio n level was not excessive. These results have clearly demonstrated the effect of food restriction in reducing elevated glucose, insulin and lipid levels associated with hyperinsulinemia and NIDDM in Psammomys o besus.