**5. Limitations of orthodox approaches in the treatment of diabetes mellitus**

Despite the significant improvements recorded from the administration of the currently available therapies in the treatment of diabetes, several undesirable side effects have been observed in the course of treatment using these therapies. Reports have shown that the success of OADs is limited by their mechanisms of action, which often address the symptoms of diabetes rather than its underlying pathophysiology. For instance, up to 2.5% and 17.5% of sulfonylurea (SU)-treated patients experience major and minor hypoglycaemia, respectively, while gastrointestinal (GI) problems affect up to 63% of metformin, and 30% of acarbosetreated patients. These side effects can have a negative impact on patient adherence to treatment, resulting in higher HbA1c levels and increased risk for all-cause hospitalization and all-cause mortality [101].

Another limitation that hinders the efficacy of OADs is the tendency of health professionals to delay initiation and intensification of therapy. OADs are frequently initiated too late in the progression of the disease and intensification is delayed and thus exposes the patient to hyperglycemia [88]. According to the recent American Association of Clinical Endocrinologists (AACE) road map guidelines, combination therapy is to be initiated when continous titration of OAD monotherapy fails to achieve target HbA1c levels (ie, ≤ 6.5%) [102].

Although insulin is the most effective antihyperglycemic agent, its initiation is also delayed to an excessive degree. Brown *et al.* estimated that the average patient accumulated HbA1c- which contribute to excess glyacemic burden (HbA1c > 8%) from diagnosis until insulin initiation, thereby increasing the prevalence of complications [103]. The economic burden of managing diabetes is also a limitation to the use of oral antidiabetic drugs especially in less developed countries where the people can scarcely afford orthodox treatment. There is therefore the need to investigate the antidiabetic effects of indigenous plants and their continuous role in the management of diabetes mellitus with a view to developing new and more effective drugs to stem the tide of the ravaging epidemic of diabetes.
