Biomedical Engineering Reference
In-Depth Information
9.1 Introduction
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia due to
reduced insulin production or insulin resistance in the body. Specifically in type 1
diabetes insulin production is markedly reduced due to the destruction of insulin
producing b cells as a result of autoimmunity. On the other hand, type 2 diabetes
results from a combined effect of insulin resistance and reduced insulin secretion
by b cells. While type 2 diabetes can be sometimes managed through the use of
oral hypoglycemic agents or lifestyle changes, type 1 patients are exclusively
dependent on insulin injections for their whole life span [
1
,
2
]. Intensive insulin
therapy combined with continuous glucose monitoring currently remains the best
treatment for type 1 diabetes. If carefully followed such therapy can improve the
quality of life and prevent or at least delay the development of end organ com-
plications, e.g., nephropathy and retinopathy. However, during long-term treat-
ment some patients develop an impaired hypoglycemia awareness that is
dangerous and can prove to be fatal [
3
]. Therefore, an ideal glucose homeostasis
without the fear of hypoglycemia can only be achieved through physiological b
cell replacement. This can be achieved through whole pancreas or islet trans-
plantation and this is the only form of b cell replacement therapy that is presently
available in certain clinics.
9.2 Pancreas and Islet Transplantation
Kelly et al. [
4
] reported the first case of pancreas transplantation in 1967. Since
then about 30,000 patients have been transplanted worldwide [
5
]. There are three
main categories of pancreas transplantation: simultaneous pancreas-kidney
transplantation (SPK) that accounts for the majority of the pancreas transplants
performed, pancreas after kidney transplantation (PAK), and pancreas transplant
alone (PTA) [
3
]. Most successful among them is SPK with highest graft survival at
10 years post-transplant [
6
]. Whole pancreas transplantation is efficient in
restoring the normal physiological glycemic control and improving the quality of
life. The main disadvantage of pancreas transplantation is the involvement of
major surgery and the use of immunosuppressive drugs. That is why an ideal
candidate for pancreas transplant is one with end-stage renal disease who will
receive a kidney transplant anyway. In the same surgical procedure pancreas can
also be included with little extra effort while the patient receives the same
immunosuppressive drugs. One major problem with pancreas transplantation is the
availability of donor pancreas compared to the huge number of patients on the
waiting list.
As compared to pancreas transplantation, the procedure of islet transplantation
is less invasive as it requires no major surgery. However, the use of immuno-
suppressive
drugs
is
common
between
both
procedures.
Although
islet
