Highly significant difference (p < 0.001) was seen at day 7 in serum cholesterol levels of different groups. Cholesterol levels were significantly lower in groups receiving NS or metformin as indicated by Table 3. No significant difference was seen between NS and metformin groups.

At day 7, the HDL levels in all the groups were similar (p >0.05) showing that NS or metformin did not significantly affect HDL levels as seen in Table 3.

A highly significant difference was seen between the different groups in TG levels on day 7. However, TG level was significantly lower than control only in group receiving 600 mg/kg NS extract as seen in Table 3.

hows highly significant difference (p < 0.001) at day 7 in LDL levels of different groups.LDL levels were significantly lower in groups receiving NS or metformin. No significant difference was seen between NS and metformin groups.

A highly significant difference was seen between the different groups in VLDL levels on day 7as shown in Table 3. However, VLDL was significantly lower than control only in group receiving 600 mg/kg NS extract.

As seen in Table 4 and Figure 1 glucose levels at Day 7 in rats receiving 600 mg/kg NS extract were found to be negatively correlated with their body weight.

Figure 1

Our study is in line with that of Qidwai et al, 2009 23 who reported that NS seeds reduced BW, BMI and waist-hip ratio, but the results were not statistically significant. In our study a highly significant decrease in glucose levels was seen after administration of NSE which was comparable to metformin. This is in confirmation with the study of Al Awadi FM et al, 1985 24, who reported a significant decrease in blood glucose produced by a plant mixture containing N. sativa.

Our study also confirms the study of Fararh et al., 200225 and El-Dakhakhny et al., 200226 who reported anti-hyperglycemic effects of NS oil in Nicotinamide-STZ induced DM hamsters, and STZ DM rats respectively.

In the present study NS effectively reduced TC, TG and VLDL levels. This confirms earlier studies which showed significant decrees in VLDL, TG and TC levels, by NS seeds in Wistar Albino rats27 as well as in humans 23. However, no significant change was seen in HDL and LDL levels. Kocyigit et al, 2009 18 reported a significant decrease in LDL and an increase in HDL levels in rats. The difference may be because the rats used in this study were non-diabetic while we used diabetic rats in our study.

A negative correlation was seen between BW before start of treatment and blood glucose levels at the end of NS treatment. This shows that NS is more effective in reducing BG if BW is higher. The reason for this is that higher BW is associated with insulin resistance. NS treatment has been shown to improve glucose tolerance as effectively as metformin 18.

Our study also confirms the study of Najmi A et al 28 who reported that NS treatment significantly reduced blood glucose levels in patients of Insulin Resistance Syndrome. The anti-hyperglycemic activity of NS may be due to insulino-tropic 25 as well as extra-pancreatic 26 effects of NS which may be attributed to the presence of Thymoquinone 16. The antihyperglycemic and hypolipidemic activity of NS coupled with its antioxidant activity against atherogenic diet induced stress 27, 18 shows that it can be used as an important food supplement in diabetic patients taking high fat diet.

Our study reported superior effect of NSE (600mg/Kg) on Triglyceride levels compared to Metformin, apart from similar effects on other lipid profile parameters, blood glucose and body weight. Moreover several studies have shown beneficial effects of Nigella sativa in prevention or treatment of various comorbidities in people with diabetes, like reduction of CRP levels 29, 30, antioxidant activity 30, nephroprotective effect 31, and improvement of endothelial function 32. This indicates the positive implication of using the NSE over metformin

Nigella sativa shows anti-hyperglycemic effects in diabetic high fat diet fed rats which is comparable to metformin. It also causes decrease in TC, TG and VLDL. Although further studies are required to advocate its use in obese DM patients.

This research was part of Short Term Studentship (STS) program of Indian Council of Medical Research (ICMR) which supports research of Undergraduate medical students.

Conflict of Interest: None

Role of Funding Source: This research was supported by intramural funding from management of Era’s Medical College and Hospital, Lucknow, U.P., India-226001.

High density lipoprotein [HDL], Nigella sativa ethanolic extract [NSE], triglyceride [TG], very low density lipoprotein [VLDL]