Association of nicotinamide and streptozotocin is being increasingly used for inducing a diabetes mellitus (DM) similar to human’s type 2 DM [6–9]. In this sequential combination, nicotinamide protects pancreatic beta cells, delaying their disappearance, improves their regeneration and controls blood glucose parameters  whereas streptozotocin has toxic effect resulting in increased formation of free radicals that alter the plasma membrane of β cells and fragmented DNA . The moderate hyperglycemic state (≥126 mg/dl) recorded in rats throughout the present experiment confirms the real diabetic status of the animals used in the present study.
In type 2 diabetic rats treated with Bersama engleriana extracts, a significant decrease (p<0.05) in blood glucose concentrations was observed when compared to respective baseline values (week 0). These results further support the hypoglycemic activity of Bersama engleriana previously reported in sugar overloaded normal rats . It is generally believed that most of the medicinal plants with antidiabetic potentials have been found to contain a variety of substances responsible for the reported activities . Thus, phytochemical tests revealed the presence of triterpenes, steroids, saponins and phenolic compounds in Bersama engleriana extracts. It has been demonstrated that triterpenes and phenols stimulate insulin secretion through their antioxidant activities [16, 17]. Oxidative stress has been shown to play a key role in the causation of diabetes. Streptozotocin produces oxygen radicals in the body, which cause pancreatic injury and could be responsible for increased blood sugar as well as lipid peroxidation. As such, antioxidants may have a role in the alleviation of diabetes . From the results obtained in this work, it could be proposed that Bersama engleriana may enhance the antioxidant defense against reactive oxygen species produced under hyperglycemic condition and this could protect beta-cells against loss, and exhibit antidiabetic activity. The in vitro antioxidant property of Bersama engleriana previously reported by  using extracts from the roots, stem bark, leaves and wood of this medicinal plant could be of great importance in the understanding of this suggested in vivo antioxidant activity of Bersama engleriana. It is a well-established fact that many medicinal plants possess antioxidant potentials which might be helpful under diabetic conditions [19–21]. Results from this work also indicate that the methanolic extract, especially the dose 600 mg/kg, produced more alleviating effects. This observation confirms the fact that methanol extracts of plants are generally known for their high contents in chemical compounds capable of producing biological activities .
With regard to the lowering blood glucose concentrations, it could be proposed that Bersama engleriana may act by (1) stimulating insulin secretion similarly to glibenclamide , (2) triggering progressive regeneration of the damaged β cells after sequential injection of nicotinamide and streptozotocin or (3) potentiating glucose uptake and use by various tissues [17, 24, 25]. The improvements observed in the body weight as well as in the relative weights of the pancreas and liver of diabetic animals after plant extract applications further support these proposed pancreatic and extra-pancreatic mechanisms of action of Bersama engleriana[26–29].
As one of the complications that followed diabetic hyperglycemia is dyslipidemia, the serum lipid profile of rats was evaluated in this study. As expected, untreated diabetic animals showed a significant increase in serum TC, LDL-C and TG concentrations against low levels of HDL-C [27, 30, 31]. This increase in serum lipids is mainly due to the increased fatty acid mobilization from adipose tissue. Since insulin has an inhibitory action on HMG-CoA reductase (3-hydroxy-3-methyl-glutaryl coenzyme A reductase), the key enzyme in cholesterol biosynthesis , insulin deficiency or insulin resistance may therefore be responsible for hyperlipidemia. Treatment of type 2 diabetic rats with Bersama engleriana extracts, especially its methanolic extract (600 mg/kg), reversed although not completely dyslipidemia as evidenced by the significant decrease (p<0.05) in TC, LDL-C and TG coupled to the increase in HDL-C (p <0.05). These alleviating effects clearly denote the antihyperlipidemic potential of Bersama engleriana, and may also account in the improvement of liver weight as above observed. It could also be suggested that this antihyperlipidemic effects of Bersama engleriana pass through a decrease in intestinal cholesterol absorption or a decrease in the biosynthesis of cholesterol specifically by decreasing the activity of HMG-CoA reductase inhibitors .