CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF STUDY
Diabetes
mellitus is a group of metabolic disorders in which a person has high
plasma glucose, either because the body does not produce enough insulin,
or because cells do not respond to the insulin that is produced. The
high plasma glucose produces the classical symptoms of polyuria,
polydipsia and polyphagia (Rother, 2007). Type 2 diabetes mellitus,
formerly non-insulin dependent diabetes mellitus or adult onset
diabetes, is a metabolic disorder that is characterized by hyperglycemia
in the context of insulin resistance and relative insulin deficiency
(Vinay et al., 2008). It has been regarded as one of the most common
metabolic diseases with the rate of 6.4 % in people aged 20-79 years and
one of the leading causes of death all over the world (Burtis et al.,
2008; Vinay et al., 2008; Rosen, 2012). Nearly 80% of the type 2
diabetes mellitus patients come from developing countries (Dhindsa et
al., 2009). Many factors, such as genetics, aging and life style, have
been involved in the development of type 2 diabetic mellitus, diagnosis
of type 2 diabetic mellitus are found to be obese (Ramarao and Kaul,
2009). Over 90% of people with diabetes mellitus are type 2 diabetics
and it is reported to be associated with certain endocrine disorders.
There have been increasing anti-diabetic drugs such as sulfonylureas,
biguanides and dipeptidyl peptidase-4 have been used to control type 2
diabetes mellitus (Murali and Saravanan, 2012; Neerati et al., 2014).
However, most of these anti-diabetic drugs have limited efficacy and
many undesirable side effects such as drug resistance, weight gain,
dropsy and high rates of secondary failure (Tahrani et al., 2010; Murali
and Saravanan, 2012). Therefore, the development of low toxicity,
effective and economic anti-diabetic drugs is still needed and has
far-reaching significance. Metformin, a class of insulin sensitizers, is
commonly used for the treatment of type 2 diabetes. While lowering the
blood glucose level, metformin can cause reduction of fat mass and
inhabitation of tumor cell proliferation (Kargulewicz et al., 2016; Huo
et al., 2017). Diabinese is equally used as an adjunct to diet and
exercise to improve glycemic control in adults with type 2 diabetes
mellitus (Murali and Saravanan, 2012).
Metformin hydrochloride, a
biguanide, is the most popular oral glucose-lowering medication in most
countries, widely viewed as ‘foundation therapy’ for individuals with
newly diagnosed type 2 diabetes mellitus. This reputation has resulted
from its effective glucose-lowering abilities, low cost, weight
neutrality, overall good safety profile (especially the lack of
hypoglycaemia as an adverse effect), and modest evidence for
cardioprotection (Inzucchi et al., 2015). A derivative of guanidine,
which was initially, extracted from the plant Galegaofficinalis or
French lilac, metformin was first synthesised in 1922 and introduced as a
medication in humans in 1957, after the studies of Jean Sterne (Sterne,
2007). Its popularity increased after eventual approval in the USA in
1994, although it was used extensively in Europe and other regions of
the world prior to that (Pryor and Cabreiro, 2015). The drug’s efficacy
has been demonstrated in monotherapy as well as in combination with
other glucose lowering medications for type 2 diabetes mellitus. Based
on these important characteristics, there continues to be extensive
interest in this compound, even many years after its incorporation into
the diabetes pharmacopeia. Interestingly, and despite this popularity,
there still remains controversy about the drug’s precise mechanism of
action, although most data point to a reduction in hepatic glucose
production being predominately involved although, recent data suggests
that some of the drug’s effect may involve the stimulation of intestinal
release of Incretin hormones (Rena et al., 2017).
Diabinese
(chlorpropamide) is an oral blood-glucose-lowering drug of the
sulfonylurea class (Inzucchi et al., 2015). It lowers the blood glucose
acutely by stimulating the release of insulin from the pancreas, an
effect dependent upon functioning beta cells in the pancreatic islets.
The mechanism by which diabinese lowers blood glucose during long-term
administration has not been clearly established (Inzucchi et al., 2015).
Extra-pancreatic effects may play a part in the mechanism of action of
oral sulfonylurea hypoglycemic drugs.