1.1 Background to the Study
Dietary control is vital in the management of diabetes. Reports from FAO (1998); WHO and FAO (2003) have shown that diets with low saturated fat, cholesterol and glycemic index as well as high contents of soluble fiber, vitamins and minerals are effective in the management of diabetes. Low glycemic foods contain sugars that digest and absorbed slowly into the blood and thus control blood sugar levels. The fiber-like substances such as gums and pectin reduced blood postprandial glucose levels (Jenkins et al., 1978; Ou et al., 2001) while diabetic subjects fed xanthan gum have lower fasting, postprandial serum glucose levels and total plasma cholesterol (Osilesi et al., 1985). Jenkins et al. (1978) reported that daily intake of 5–10 g of soluble fiber from different sources reduced serum cholesterol by 5–10%. Fruits serve as one of the best sources of dietary fiber, minerals, Vitamins A, C and E and frequent intake of vegetables and fruits have demonstrated a lowered risk of diabetes, heart disease, hypertension, stroke and cancer (Southon, 2000; Wargovich, 2000). Fruits supply carbohydrates in the form of soluble sugars, cellulose and starch (Nahar et al., 1998) and serve as source of nutrient, appetizer and food supplement in a world faced with problem of food scarcity.
Diabetes mellitus (DM) is a worldwide endemic disease in terms of occurrence, cost of medical care, and general complications (King et al., 1998). The metabolism of protein, carbohydrate and fat are affected in diabetic conditions, resulting in hyperglycemia. DM complication is mainly associated with a high risk of coronary heart disease (Giugliano et al., 1996), atherosclerosis, stroke and peripheral vascular disease. The incidence of DM world wide, is projected to increase from 4% in 1995 to 5.4% by the year 2025 (Mohamed et al., 2006), with the utmost increases set to occur in the developing countries of Africa, Asia and South America (WHO, 2008).
According to WHO (1994) and American Diabetes Association (2008), diabetes mellitus can be classified into insulin-dependent diabetes mellitus, IDDM (type 1 diabetes mellitus) and non- insulin- dependent diabetes mellitus, NIDDM (type 2 diabetes mellitus). Insulin-dependent diabetes mellitus is caused by cellular-mediated autoimmune damage to beta cells of the pancreas, accounts for about 5% to 15% of diabetic cases and occurs mostly in children or adolescents (Ranjan and Ramanujam, 2002). Genetics and environmental factors are implicated in the formation of IDDM. Administration of exogenous insulin is thus required to avert ketosis and preserve life (Lokesh and Amit, 2006). Non- insulin- dependent diabetes mellitus starts as insulin resistance, accounts for 85-95% of cases globally and occurs usually in adults of 40 years and above (WHO Regional Office for the South-East Asia, 2009). It is associated with hyperglycemia and glycosuria. The risk factors increases with age, lack of physical activity, obesity and impaired glucose tolerance.
Insulin resistance occurs when glucose is not properly utilized by the cells leading to high blood glucose in circulation. To maintain blood glucose level, the kidney excretes exess blood glucose through the urine and glucosuria occurs with increased excretion of water and sodium when blood glucose level exceeds the renal threshold (160 – 180 mg/L). The failure to use glucose by the body cells, results to increase appetite (polyphagia) (Robinson et al., 1986). The summary of the symptoms of diabetes is shown in Figure 1.