**1. Introduction**

### **1.1. Diabetes: Definition, aetiology and classification**

The term "diabetes", when used alone, generally refers to diabetes mellitus (DM) and not a rare, unrelated disease called diabetes insipidus. DM is a metabolic disorder resulting from a defect in insulin secretion, insulin action, or both. Insulin deficiency in turn leads to chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism [1,2]. The magnitude of the challenge that diabetes presents to health services is enormous [3].

DM was traditionally classified based on whether or not the patient is insulin dependent or independent [4]. However, there has been a paradigm shift in the classification of DM from one based on the need for insulin therapy to maintain glycaemic control and prevent ketosis to that basedon theunderlying aetiopathogeneticmechanisms [5].The current classes ofDMandtheir aetiopathogenetic mechanisms are (i) Type 1A (auto-immune), (ii) Type 1B (non-auto im‐ mune or idiopathic) [6], (iii) Type 2 (insulin resistance), (iv) Gestational (diagnosed for the first time in pregnancy but usually characterized by insulin resistance) and (v) other specific aetiologies (secondary to other diseases and identified gene mutations) [5]. Once considered a disease of acute onset, it is now generally accepted that the 1A subtype is a genetically deter‐ mined chronic immune-mediated disorder that leads to selective loss of pancreatic insulinsecreting β-cells [6]. The classic point of view regarding type I diabetes mellitus (T1DM) pathogenesiswas that,ingeneticallypredisposedindividuals, some environmentalfactorsmay triggeranautoimmuneprocessthatleadstoβ-celldestruction;butdespiteconsiderableprogress over recent years, the autoimmune process underlying T1DM is still poorly understood [6].

© 2014 Akinmoladun et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The high blood glucose level (hyperglycaemia) that accompanies T1DM and type 2 diabetes mellitus (T2DM) can cause serious health complications including ketoacidosis, kidney failure, heart disease, stroke, and blindness. Patients are often diagnosed with diabetes when they see a physician for clinical signs such as excessive thirst, urination, and hunger [7]. The direct symptoms of type-2 diabetes can be mild and may cause minimal interruption to activities of daily living. However, it is the complications of the disease which lead to damage to vital organs, and consequently, to substantial morbidity and mortality.

**3. Pathological complications of diabetes mellitus**

tions are due to diabetes [26].

subset of age-related cataract [32,33].

diabetic ED [35]

Persistent hyperglycaemia and the development of diabetes-specific microvascular (retinop‐ athy, neuropathy and nephropathy) and macrovascular (heart attack, stroke and peripheral arterial disease) complications are the main characteristics of all forms of diabetes mellitus. The importance of protecting the body against persistent elevation of blood glucose cannot be overemphasized because its direct and indirect effects on the human vascular system are the major cause of morbidity and mortality in both T1DM and T2DM [22]. Hospitalisations for complications account for more than half of the healthcare costs of T2DM and three-quarters of people with diabetes die from cardiovascular disease. Research has shown that the risk of development of both microvascular and macrovascular complications associated with elevated blood glucose increases with the length of time blood glucose is uncontrolled [23,24]. As a result of the association of diabetes with accelerated atherosclerotic macrovascular disease affecting arteries that supply the heart, brain and lower extremities, patients with diabetes have a much higher risk of myocardial infarction, stroke and limb amputation [25]. Lower limb amputations are at least 10 times more common in people with diabetes than in non-diabetic individuals in developed countries; more than half of all non-traumatic lower limb amputa‐

Antidiabetic Botanicals and their Potential Benefits in the Management of Diabetes Mellitus

http://dx.doi.org/10.5772/57339

141

Diabetes is one of the leading causes of visual impairment and blindness in developed countries [27]. Retinopathy may begin to develop as early as 7 years before the diagnosis of diabetes in patients with T2DM [28]. Osmotic stress from sorbitol accumulation has been postulated as an underlying mechanism in the development of diabetic microvascular complications, including diabetic retinopathy [22]. According to Massin *et al* [29] lens opaci‐ fication leading to cataract is a frequent comorbidity of diabetes, as adults with T2DM are five times more often affected than the general population. They also reported that while juvenile diabetic cataract is rare, adult-onset, mostly cortical cataract in T2DM patients is similar to agerelated cataract in the general population, except for an earlier onset and greater prevalence [29,30]. Major risk factors for cataract in T2DM include hyperglycaemia, diabetes duration and the presence of diabetic retinopathy, although specific risk factors or markers may differ according to cataract subtype. Smoking, for example, is associated with nuclear opacities, whereas ultraviolet radiation increases the risk for cortical opacities, and high blood pressure and corticosteroids raise the odds for subcapsular cataract [31]. Various pathophysiological mechanisms are involved in cataract formation, including osmosis-driven lens overhydration triggered by the polyol pathway (mostly ascribed to juvenile cataract), lens protein glycation and an excess of free radicals, with the latter being particularly associated with the nuclear

Studies have shown an increased incidence of erectile dysfunction (ED) in diabetes patients. In addition, ED appears to arise about 10 years earlier in diabetic patients than in the general population [34] and is more severe, decreasing health-related quality of life. ED is most often a forewarning of cardiovascular disease; thus, the treatment of ED among diabetics is a priority. Diabetic ED is multifactorial in aetiology and more resistant to treatment compared with non-

Diabetes in the young is often categorized as Type 1 and this comprises the auto-immune Type 1A and non-auto immune Type 1B. T2DM which is mainly diagnosed in adults is increasingly being reported in young people. The increased prevalence of T2DM in young people is associated with the increasing rates of obesity in young people. Type 2 diabetes accounts for 90% to 95% of all cases of diabetes [8-10].
