## 4 Discussion
The management of dietary fat and especially the decrease of total fat, saturated fat and trans-fatty acids intake is proposed [42]. MUFA and PUFA can be used as alternatives to maintain lipid intake within accepted ranges or to ameliorate the lipid profile [41]. Therefore, nutrition therapy is crucial for T1D management and inflammation. In the present study, the concentration of plasma MUFA was increased in diabetic rats following the pistachio diet compared to those fed with the standard diet, demonstrating that dietary patterns affected the lipid profile in a favorable manner, as elevated plasma MUFA following a high-MUFA dietary intervention has been associated with improvements in insulin sensitivity [43]. What is more, in DPD rats, dietary pistachio enhanced the concentration of oleic acid (18:1\(\omega\)9) compared to rats fed a standard diet. Oleic acid is found in olive oil-rich diets, such as the Mediterranean diet, and it is suggested that it can improve blood sugar control and insulin sensitivity [44; 45]. The beneficial effects of diets high in MUFA are well documented [46], while the composition of the lipid profile in plasma and VAT is at least partially reflected by the diet. It is widely accepted that dietary fat and Its fatty acid composition interfere with lipid metabolism in VAT [47; 48]. Triacylglycerglycerols of VAT mainly include 18:1\(\omega\)9, 16:0 and 18:2\(\omega\)6 [49], which were also confirmed in our study, where in all groups, the above-mentioned fatty acids were detected. In the VAT of diabetic rats of both groups, decreased concentrations of 16:0, SFA and 18:3\(\omega\)3 compared to healthy animals were detected, which is in accordance with the results reported by other studies [50; 51]. Pistachio consumption had no effect on these alterations and, therefore, these can be attributed to the diabetic state. The decrease in total SFA may imply that the diabetic state worsens their biosynthesis and elongation process, but it may also be due to a decrease in palmitic acid, which cannot be further elongated to other saturated fatty acids at the same rate [52]. The predominance of 16:0 fatty acid, which is lower in diabetic animals compared to the animals of the control group, leads to a significant reduction in total SFA seen in diabetic groups, while a non-significant decreasing trend prevails in most of the other SFA. Dietary pistachio led to significantly increased levels of 18:1\(\omega\)9 and MUFA, whereas 18:2\(\omega\)6, total \(\omega\)6 and PUFA were decreased in the VAT of diabetic and healthy animals compared to groups fed with the standard diet. These alterations seem to be an outcome of pistachio supplementation, as they occur in both PD and DPD groups, regardless of the disease state. Pistachio is rich in oleic acid (18:1\(\omega\)9) (and particularly 69.6% in total FAs) and MUFA (73%) [13]; therefore, the dietary intake of these fatty acids leads to their elevated presence in the VAT of PD and DPD, compared to CD and DCD groups. Other MUFA, apart from 18:1\(\omega\)9, were detected at similar levels in all groups. Increased MUFA in VAT has been reported after a 4-week olive-oil diet in rats [53], accompanied by an increase in oleic acid, results that underline that pistachio supplementation could possibly affect fatty acid profile in a similar manner, which has been associated with an ameliorated glycemic response in T1D state [54]. The control groups, CD and DCD, had significantly elevated amounts of 18:2\(\omega\)6 compared to groups that received the pistachio nuts (PD and DPD). Although pistachio contains adequate amounts of PUFA and particularly 18:2\(\omega\)6, their content, as well as that of total \(\omega\)6, was not enhanced in the VAT of PD and DPD groups. This is probably due to the supplementation of the control diet with corn oil (in order to equilibrate total fat and energy content of the two different diets), which is also rich in 18:2\(\omega\)6.