Comparative evaluation of hypoglycaemic activity of some Indian medicinal plants in alloxan diabetic rats

Essential trace elements are required by man in amounts ranging from 50 micrograms to 18 milligrams per day. Acting as catalytic or structural components of larger molecules, they have specific functions and are indispensable for life. Research during the past quarter of a century has identified as essential six trace elements whose functions were previously unknown. In addition to the long-known deficiencies of iron and iodine, signs of deficiency for chromium, copper, zinc, and selenium have been identified in free-living populations. Four trace elements were proved to be essential for two or more animal species during the past decade alone. Marginal or severe trace element imbalances can be considered risk factors for several diseases of public health importance, but proof of cause and effect relationships will depend on a more complete understanding of basic mechanisms of action and on better analytical procedures and functional tests to determine marginal trace element status in man.

Medicinal herbs used in indigenous medicines in crude forms for the management of diabetes mellitus, contain both the organic and inorganic constituents. It is known that certain inorganic mineral elements (potassium, zinc, calcium, traces of chromium, etc.) play an important role in the maintenance of normal glucose-tolerance and in the release of insulin from beta cells of islets of Langerhans. In the present study, 30 hypoglycaemic herbs were selected from indigenous folk medicines, Ayurvedic, Unani and Siddha systems of medicines. Special emphasis was given to their inorganic parts by carefully preparing ash (which contains mainly mineral elements) of the specific parts of the herbal samples under study. Next, the single dose effect on the oral glucose tolerance test (GTT) was studied using previously fasted albino rats. Similar effects were also compared with their organic parts of the concerned herbal samples in the form of 95% ethanolic extracts. In certain inorganic samples, more pronounced action (as glucose tolerance factor) were noticed than their corresponding organic parts.

In order to investigate the relationships between metals zinc [Zn], copper [Cu], magnesium [Mg], or Calcium [Ca] and noninsulin-dependent diabetes mellitus, 65 patients of newly diagnosed noninsulin-dependent diabetes mellitus and 54 nondiabetic healthy controls were studied. The concentrations of selected metals in fasting blood samples and 24-h urine collections were determined. Hyperzincuria and hypermagnesuria were detected in diabetic patients (p < 0.01). The diabetics also had lower Zn and Mg, and higher Cu, and Ca levels in their plasma than those of the controls, but the statistical differences in Ca and Mg were not significant. Significantly lower Zn and higher Ca levels in erythrocytes were found in diabetic patients (p < 0.01). There is evidence of a significant difference in metals status between diabetic patients with or without the specific complications. This study further indicates that patients with NIDDM on Taiwan also have distinct changes in their metals status, and these perturbations are associated with some diabetic complications.