Sarada Bulchand (Duke-NUS Graduate Medical School, Singaporee)
Photo credit: David Robert Bliwas/Flickr/CC
382 million people suffer from diabetes today. By 2035 there will be over 500 million diabetics in the world, as predicted by the International Diabetes Federation . In developing countries, the majority of people with diabetes are in the age range of 45–64 years while in developed countries the majority are more than 60 years of age. Current statistics point to a steadily increasing number of diabetics in Asia. China heads the world diabetes list with the highest absolute number of diabetics at 92 million cases, followed by India with 62 million recorded diabetics in the age group of 20–79 years. What used to be considered a disease of developed nations and Western countries, is now turning into an Asian epidemic. This is largely attributed to a rising population of aging people, higher rates of obesity, poor lifestyle habits and earlier detection of diabetes .
What is Diabetes?
Diabetes was first recognized by the ancient Egyptians in 1500 BC as a condition in which a person urinated excessively. The Greek physician Aretaeus named the condition diabetes which means 'to pass through'. Several astute observations and landmark discoveries transformed this disease with a death sentence into a condition that now has more optimistic outcomes, although a cure has remained elusive. Simply put, diabetes is a condition of high blood sugar (hyperglycemia). An individual with overt diabetes is unable to either use or produce sufficient insulin, the hormone that regulates the uptake of glucose from the blood into peripheral tissues. Broadly classified into Type 1, Type 2 and gestational diabetes, physicians and scientists today are overwhelmed by the variability in disease presentation, especially in the pre-diabetes stages. 90% of diabetics suffer from Type 2 diabetes that often develops in adulthood and whose prevalence rises with increasing age.
Obesity and Insulin Resistance Prominent Risk Factors for Type 2 Diabetes
Obesity and insulin resistance or the inability of tissues to sense the hormone insulin which results in impaired fasting glucose and impaired glucose tolerance, is often a prelude to overt Type 2 diabetes. Insulin, a peptide hormone produced by the beta cells of the pancreas, acts on peripheral tissues, like the muscle, leading to the uptake of glucose from the blood while inhibiting production of glucose from the liver, thus maintaining levels of blood glucose within a very narrow homeostatic range. When insulin is not sensed by target tissues, glucose disposal is reduced and levels of glucose in the blood rise. The high level of blood glucose further stimulates the pancreas to secrete more insulin. This futile effort to reduce blood glucose places immense stress on the pancreas that eventually results in failure of the beta cells to produce insulin, leading to frank diabetes. The biggest cause for concern is that this process is gradual and asymptomatic and can therefore go undetected for several years.
Varied Diabetic Complications
Chronic hyperglycemia (increased blood glucose) results in several complications of the heart, blood vessels, eyes, kidney and nerves. These complications could take up to several years to manifest, and are hence most often observed in older patients, especially those who are unable to or do not manage their glucose levels efficiently. 50% of patients with diabetes die of cardiovascular events due to the increased risk of heart disease and stroke. Nerve damage and reduced blood flow to the feet result in infection and the formation of ulcers, with the eventual need for amputation of the leg. Diabetic retinopathy, long term damage to the blood vessels in the retina, is a common complication resulting in blindness. Diabetes is also a common cause of kidney failure. Interestingly, diabetes also has implications on brain function, increasing the risk for dementia, possibly due to altered brain metabolism and accelerated brain aging . Hence, this is a condition of great complexity that affects multiple organ systems.
Prevalence of Diabetes Increases with Age
The association between aging and diabetes is not well understood. Several theories have been proposed. These range from aging related endocrine changes to the effects of abdominal obesity on whole body metabolism. Increases in the levels of leptin, the hormone that drives appetite is positively correlated with insulin resistance in older people . Also, as people age between 40–70 years of their life, lean mass decreases and adiposity increases. This results in less glucose disposal due to a reduction in muscle tissue, accompanied by increased fat storage . Additionally, as people age, mitochondrial function is compromised. Severe mitochondrial dysfunction is known to increase oxidative stress, compromise cellular function and is often associated with insulin resistance . Together with reduced physical inactivity, age related bodily changes predisposes people to become obese. Several studies have indicated that the inappropriate storage of excess fat, the inability of adipose tissue to expand and accommodate extra fat, and the release of inflammatory molecules from adipose tissue, might be causal factors of insulin resistance .
Interestingly, there is an emergence of non-obese diabetics, especially in developing nations in Asia. This calls for greater scrutiny of the mechanisms that could lead to diabetes in non-obese conditions. Previous risk criteria of body mass index (an indirect measure of obesity) are being re-evaluated since several non-obese diabetics could go undetected. Research has pointed to the importance of susceptibility genes . Studies have shown that diabetes has a strong hereditary component, thereby making certain ethnic groups more predisposed to developing the condition. Besides genetics, other unknown environmental factors are also likely to contribute to the development of this metabolic condition. Therefore, not all old people develop diabetes.
Management of Diabetes in the Elderly and Socioeconomic Implications
Diabetes must be well managed in order to reduce the risk of long term complications. Although considered a disease of the working class, it is the elderly who struggle the most in trying to cope with the complications that arise from poorly managed diabetes. Clinical presentations in an elderly diabetic with other non-diabetes related underlying conditions might be very different from that of a younger diabetic. Unique complications of diabetes in the elderly may include cognitive decline, drug related hypoglycemia, physical disabilities and other geriatric syndromes. Homeostatic imbalance leads to symptoms associated with the weakest organ system . Often, basic functionality of the elderly is affected. Elderly diabetics also have unique management problems which leads to significant impacts on efficient elder care, and places tremendous responsibility on caregivers. Awareness of the condition and the long term advantages of managing glucose levels is critical. Yet, regulating glucose levels too tightly may not be practical in an elderly patient compared to a younger diabetic. Strict regimes and regular glucose monitoring may not be feasible in the elderly due to aging-related disabilities unrelated to diabetes.
On average, the cost of managing diabetes is about $120,000 per adult detected at age 25–35 assuming they live until 70–80 years of age. This significantly high cost may be met by patients in developed nations who have access to sufficient funds. The scenario in developing nations is quite different. Difficult socioeconomic conditions, lack of sufficient knowledge, decreased health awareness and reduced access to medical facilities often result in the disease going undetected until it is fairly advanced. Often it is only the presence of diabetic complications like excessive weight loss, poor vision and reduced sensation in the feet that lead the patient to the clinic. People that are unaware of the risk factors leading to diabetes, and do not have the means to manage the disease, bear the brunt of living with diabetes and its complications. Greater than 80% of deaths due to diabetes occur in developing nations.
Several approaches have been proposed to reduce the risk of developing diabetes. Everyone after the age of 40 must have 6 monthly blood sugar checks. The fairly long and asymptomatic period before the onset of diabetes is typified by mild hyperglycemia and insulin resistance. Progression to diabetes from this stage can be reduced through early detection and lifestyle modification. Balanced nutrition and regular exercise are the first line of interventions, although it is not clear how much exercise is required for an older person to regain optimal levels of insulin sensitivity. Regimes need to be individualized and monitored closely. Regular checkups must be conducted 3–4 times a year. Studies have conclusively shown that reducing body weight and regulating lipid levels has beneficial effects on insulin sensitivity and glucose disposal. However, in some cases, based on other underlying conditions, caloric restrictions and sufficient exercise to reduce body weight may be difficult to implement. In these cases, drug therapy is applied using the best drug combination that often include insulin sensitizers and insulin itself. For elderly patients, it is not uncommon that an anti-inflammatory compound like low dose aspirin be administered to reduce the risk of developing insulin resistance and cardiovascular complications. Research has shown that drug therapy must be individualized due to the complex and multi-organ nature of this disorder. Patient education is equally critical in the management of diabetes in the elderly. Group classes are cost effective and active participation leads to more motivated learning. Elderly diabetics need to be encouraged to understand and manage their own disease. Reinforcing the importance of monitoring glucose levels is critical. Once they are able to self-monitor glucose levels their disease can be better managed.
Diabetes in the elderly is growing rapidly. Diagnosing and treating elderly diabetics poses unique challenges due to variable and atypical clinical presentations of diabetes and its chronic complications. Disease management must be personalized and glycemic control must be regulated suitably by taking into consideration age, comorbidities, life expectancy and severity of vascular conditions. Patient education on self-monitoring of blood glucose would reduce the risks of drug induced hypoglycemia. Lifestyle changes like increased physical activity and dietary modifications to reduce abdominal fat are the best intervention but are not always feasible in the elderly. Preventive measures taken early could delay the onset of such a disease. Further research to understand the pathology of diabetes in the elderly would assist in more efficient management of the condition.
About the Author
Dr. Sarada Bulchand is a postdoctoral research fellow and teaching scholar at Duke-NUS Graduate Medical School, Singapore. She received her Bachelor's (Hons) in Life Science and Biochemistry from St. Xavier's College, Mumbai, India. She went on to do her Masters in Molecular Biology at the Tata Institute of Fundamental Research, Mumbai and obtained her Ph.D. in Molecular Biology from Temasek Life Sciences Laboratory, National University of Singapore in 2010, during which she was awarded the Singapore Millennium Foundation Scholarship.
Her research career has been diverse with sprinklings of neurobiology, developmental biology and metabolism in model systems from mice, human cell lines, fruit flies and zebra fish. Her keen interest in 'bench to bedside' research brought her to the Program in Cardiovascular and Metabolic Disorders at Duke-NUS. Her current research focuses on the mechanisms of lipid induced insulin resistance and the metabolic syndrome. Besides her scientific pursuits she is also one of the coordinators for the pre-med Bench to Bedside course at the National University of Singapore and Nanyang Technological University, and enjoys science writing. She is an avid nature lover, bird watcher and musician when time permits!
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