Introduction

Diabetes care systems for older people require an integrated multidimensional approach involving general practitioners, hospital specialists and other members of the healthcare team. There should be an emphasis on diabetes prevention and its complications, early treatment for vascular disease and functional assessment of disability due to limb problems, eye disease and stroke.

Inequalities of care are common in many healthcare systems due to variations in clinical practice, particularly in relation to older people. This may be manifest as a lack of access to services, inadequate specialist provision, poorer clinical outcomes and patient and family dissatisfaction. The recent development of clinical guidelines that are responsive to the needs of older people with diabetes may be an important step to minimize deficits in care from country to country, worldwide.

Type 2 diabetes mellitus is a common disabling chronic cardiovascular and medical disorder that has a tremendous health, social and economic burden and has a high prevalence of 10–30% in subjects above 65 years of age across Europe. About 60% of total healthcare expenditure on diabetes in this special group can be accounted for by acute-care hospitalizations and compared with non-diabetic counterparts, the relative risk for admission to hospital is 5.0. At any one time, about one in 12 district hospital beds is occupied by older people who have diabetes and their length of stay is double that of non-diabetic inpatients. The introduction of insulin to their regimen results in a quadrupling of expenditure, presumably because of the additional resources required in both hospital and community settings to monitor and support the use of insulin.

A direct approach to the metabolic management of type 2 diabetes in older subjects is to concentrate on strategies designed to limit and ameliorate both defective insulin secretion and insulin resistance. Type 2 diabetes represents a cluster of cardiovascular risk factors that pose a significant vascular threat and, in ageing subjects, the added effects of ageing and renal impairment increase the impact of this syndrome, and some of the features may be present up to 10 years before the onset of overt hyperglycaemia, thus increasing the cardiovascular risk before the onset of diabetes. Since up to 50% of the variability in insulin action in insulin-resistant states may be associated with lifestyle differences such as obesity, physical activity levels and cigarette smoking, it becomes obvious that environmental, preventative and health promotional strategies are of vital importance in limiting the impact of this epidemic.

Management of diabetes in older people can be relatively straightforward, especially when patients have no other comorbidities and when vascular complications are absent. In many cases, however, special issues arise that increase the complexity of management and lead to difficult clinical decision-making. It is therefore not surprising that the present state of diabetes care for older patients varies throughout Europe and North America. Although geriatric diabetes is developing as a subspeciality interest in the UK, there is little evidence of its presence in other national diabetes care systems and virtually no specific provision for those who are housebound or in institutional care. This chapter can be considered to be a learning programme that aims to provide a succinct but comprehensive review of diabetes care for older people, focusing on special areas of concern.

We have identified two principal aims: (1) to develop and enhance the knowledge and application of the principles of diabetes and diabetes care in older persons and (2) to provide clinicians with the knowledge and skills and to influence attitudes to maximize their effectiveness in applying this learning within their own clinical setting. In addition, we have suggested that clinicians who study this chapter in depth should be able to demonstrate (1) an in-depth understanding of diabetes in older people and to analyze their own organization’s provision and care, with a view to enhancing local care; and (2) an understanding of the means by which the diabetes care team in their own organization and key players in their own community can be engaged in improving the quality of diabetes care for older people. Further goals might include the ability to (3) reflect on their personal learning and apply that learning to the approaches they take with team members, other care professionals, patients and carers, and (4) analyse and evaluate outcomes in the delivery of care to older people who have diabetes, taking into account the roles of other care professionals and the beliefs of people from different ethnic and cultural backgrounds.

Epidemiology, Pathogenesis and Modes of Presentation

The WHO estimates that in 2011 there are around 350 million individuals with diabetes worldwide, and that number is projected to increase to over 450 million by 2030. Several important risk factors (Table 101.1) are likely to underpin this increase in prevalence, such as advancing age of the population, greater numbers of people from ethnic minority backgrounds adopting a ‘transitional’ lifestyle, greater levels of overweight and obesity and more sedentary lifestyles. From an epidemiological perspective, ageing is an important factor: in the USA, the number of people with diabetes aged 75 years and over doubled between 1980 and 1987. In most populations, peak rates are generally found in the sixth decade and subsequently, although in Pima Indians the peak rate is between the fourth and fifth decades.

Table 101.1 Risk factors for diabetes mellitus in older subjects.

Most developed countries have a prevalence rate of about 17% in white elderly subjects and 25% in non-white subjects. The prevalence in white British elderly is only around 9% although the prevalence in non-white British elderly is about 25% and the prevalence in British care homes is 25%.

There is an increasing view that diabetes in the elderly has a genetic basis.1 Older people with a family history are often more likely to develop this illness as they age. In genetically susceptible people, various factors may increase the likelihood of type 2 diabetes developing. Elderly patients with diabetes have normal hepatic production of glucose, which is in contrast to younger subjects.2 In lean elderly subjects, the principal defect appears to be impaired glucose-induced insulin release, whereas in the obese elderly, resistance to insulin-mediated glucose disposal is the major problem.2

Multiple drugs, reduced physical activity and a diet with low intake of complex carbohydrates also contribute to this increasing prevalence. Further research into discovering the molecular abnormalities in older people with diabetes is warranted.

Modes of Presentation

Diabetes in older people has a varied presentation and may be insidious, which ultimately delays diagnosis3 (Table 101.2). Detection of diabetes during hospital admissions for other comorbidities or acute illnesses is relatively common, although even when hyperglycaemia has been recognized initially, about half of the subjects receive no further evaluation for diabetes or treatment.4 Some patients do not have the classic features of either diabetic ketoacidosis or hyperosmolar non-ketotic coma but present with a ‘mixed’ disturbance of hyperglycaemia (blood glucose levels 15–25 mmol l−1), arterial blood pH of 7.2–7.3 (not particularly acidotic) and without marked dehydration or change in level of consciousness.

Table 101.2 Varying presentation of diabetes in older people.

Impact of Diabetes Mellitus

The majority of the elderly diabetic population is at increased risk of developing foot ulcers and various risk factors have been identified (Table 101.3). Peripheral sensorimotor neuropathy, which is the primary cause or contributory factor in the vast majority of cases, may cause common symptoms of numbness, lancinating and burning pain, ‘pins and needles’ and hyperesthesia, which is typically worse at night and evidence of high foot pressures leading to gait disturbances, falls and other foot injuries. The presence of visual loss may exacerbate the consequences of this situation.17

Table 101.3 Risk factors for foot ulceration in the elderly.

Erectile Dysfunction

After the age of 60 years, erectile dysfunction (ED) may affect 55–95% of diabetic men, while the corresponding figure for non-diabetic counterparts is 50%.18 ED is defined as the inability to attain and maintain an erection satisfactory for sexual intercourse and is a complex problem involving several mechanisms: vasculopathy, autonomic neuropathy, hormonal dysregulation, endothelia dysfunction and psychogenic factors have all been implicated. Drug-related causes may be a particular problem in older patients, with thiazide diuretics, cimetidine, β-blockers and spironolactone especially being implicated. An alcohol history must be looked for. ED is evaluated initially with an interview with the patient and sexual partner where appropriate. A comprehensive history, full medical examination, blood testing for diabetes control, lipids, testosterone and thyroid function tests are necessary. Other more sophisticated tests are available through diabetes ED clinics in most large centres and may involve testing for prolactin, other gonadotrophins and nocturnal penile tumescence. For many older patients, extensive testing is often avoided. Type 5 phosphodiesterase inhibitors appear to be effective for the treatment of erectile dysfunction in carefully selected older people with diabetes.19, 20

Metabolic Comas

Older subjects with diabetes may present with either diabetic ketoacidosis (DKA) and hyperglycaemic hyperosmolar non-ketotic (HONK) coma. HONK occurs predominantly in subjects aged over 50 years. Compared with the young, older subjects with hyperglycaemic comas have a higher mortality, have a greater length of stay in hospital following admission, are less likely to have had diabetes diagnosed previously, are more likely to have renal impairment and require a greater amount of insulin as treatment.21

The tendency for hyperosmolarity in HONK comas may be worsened in elderly people, who may not appreciate thirst well, may have difficulty drinking enough to compensate for their osmotic diuresis and may also be on diuretics. It also appears that hyperosmolarity not only worsens insulin resistance but may also inhibit lipolysis.

Death may be due to the metabolic disturbance and to acute illnesses such as pneumonia and myocardial infarction. The cause of the hyperglycaemia may be infection, infarction, inadequate hypoglycaemic treatment or inappropriate drug treatment. Residents of care homes are also at increased risk of HONK coma associated with appreciable mortality.22 Thiazide diuretics and steroids are known to increase blood glucose levels and may precipitate DKA; thiazide diuretics and frusemide may be particularly likely to precipitate HONK coma.

Diabetes-Related Disability, Cognitive Dysfunction and Depression

Diabetes is associated with both functional impairment and disability. The wide spectrum of vascular complications, acute metabolic decompensation, adverse effects of medication and the effects of the condition on nutrition and lifestyle behaviour may all create varying levels of impairment and/or disability. These changes may have adverse rebound effects on vulnerability to other comorbidities, independence and quality of life.

In the 1998 Health and Retirement Survey (>6300 subjects aged 51–61 years at baseline), diabetes was identified as an important predictor of failing to recover from a mobility difficulty over a 2-year follow-up period.23 In a systematic literature review of longitudinal studies examining the relationships between various risk factors and functional status outcomes,24 diabetes was one of five conditions (others were hypertension, stroke or TIA, arthritis), which reported 10 or more studies showing a significant association between the risk factor and subsequent functional decline.

In a study examining the relationship between various chronic disease states and disability, a survey from Madrid, Spain,25 of 1001 subjects aged 65 years and over living at home showed that diabetes was one of four chronic diseases (the others were cerebrovascular disease, depression/anxiety disorders) that had a strong association with disability [OR = 2.18 (95% CI, 1.24–3.83)].

The Welsh Community Diabetes Study12 revealed significant excesses in physical {Barthel activities of daily living (ADL), p  <  0.0001; extended ADL, p  <  0.0001; cognitive [Mini Mental State Examination (MMSE)], p  <  0.001; clock test, p  <  0.001}, mobility (use of walking aid, p  <  0.01) and visual disabilities [Snellen visual acuity (VA) chart, p  <  0.01] in diabetic subjects assessed by objective measures.

In a cross-sectional survey of community-dwelling older Mexican Americans aged 65 years and over (n = 2873), the presence of diabetes predicted poorer performance on tests of lower limb function.26

The Third National Health and Nutrition Examination Survey (NHANES III) revealed that diabetes was a major cause of physical disability among subjects aged 60 years and over.27 Disability in at least one of the physical tasks examined was reported in 63% of diabetic women (controls, 42%) and 39% of diabetic men (controls, 25%), with stronger associations between diabetes and more severe forms of disability. Diabetes was shown to have a 2–3-fold increased likelihood of a mobility disorder, with coronary heart disease being a major contributor to this excess disability in both sexes and stroke being an important contributor among men.

Other studies that have examined this relationship include the Women’s Health and Ageing Study (2002)28 and the Study of Osteoporotic Fractures (2002).29 In the latter study, in community-dwelling white women aged 65–99 (mean 71.7) years, diabetes was associated with a 42% increased risk of any incident disability and a 53–98% increased risk of disability for specific tasks, for example, walking two to three blocks on level ground or doing housework.

Diabetes in the elderly is associated with an increased risk of falls and fractures.30.31 This increased risk can be explained by many of factors noted above, including peripheral neuropathy, reduced vision and impaired strength and mobility. Insulin therapy is associated with increased falls. This is probably due in part to more severe disease and/or hypoglycaemic episodes. With regard to the latter, a low A1C in insulin users was associated with an increased risk of falls.30

Cognitive Dysfunction

A decline in cognitive function has been demonstrated in older subjects with type 2 diabetes.32 This can be demonstrated using relatively straightforward tests such as the Folstein MMSE33 or the clock test.34

The Zutphen Study (1995)35 and the Kuopio Study (1998)36 showed that impaired glucose tolerance (IGT) is linked to cognitive dysfunction and increased serum insulin may be associated with decreased cognitive function and dementia in women. The Rotterdam Study (1996) showed that type 2 diabetes may be associated with both Alzheimer’s disease and vascular dementia,37 and the Rochester Study (1997) demonstrated that the risk of dementia is significantly increased for both men and women with type 2 diabetes.38 In a 7 year follow-up study (the Hisayama Study, 1995), type 2 diabetes was associated with an increased risk of developing vascular dementia.39 Poor glucose control may be associated with cognitive impairment that recovers following improvement in glycaemic control.40 A prospective cohort study involving 682 women with self-reported diabetes (mean age of population sample 72 years) followed up for 6 years indicated a twofold increased risk of cognitive impairment and a 74% increased risk of cognitive decline.41 Women who had had diabetes for longer than 15 years had a threefold increase of having cognitive impairment at baseline and a doubling of the risk of decline.

In the Framingham Study (1997), type 2 diabetes and hypertension were found to be significant but independent risk factors for poor cognitive performance (on tests of visual organization and memory) in a large prospective cohort sample followed for over 20 years.42 This relationship between cognitive decline and with the presence of either diabetes and hypertension was also observed in the Atherosclerosis Risk in Communities (ARIC) Study (2002) in a 6 year follow-up of nearly 11 000 individuals aged 47–70 years at initial assessment.43 Hyperinsulinaemia in hypertension has also been shown to be associated with poorer cognitive performance.44

Various benefits may accrue from the early recognition of cognitive impairment in older people with diabetes (Table 101.4). Depending on its severity, cognitive dysfunction in older diabetic subjects may have considerable implications, which include increased hospitalization, less ability for self-care, less likelihood of specialist follow-up and increased risk of institutionalization.45

Table 101.4 Benefits of early recognition of cognitive impairment in diabetes.

Cognitive dysfunction may result in poorer adherence to treatment, worsen glycaemic control due to erratic taking of diet and medication and increase the risk of hypoglycaemia if the patient forgets that they have taken the hypoglycaemic medication and repeat the dose.

Type 2 Diabetes Mellitus and Depression

Diabetes was found to be significantly associated with depression, independent of age, gender or presence of chronic disease in one study;46 also, the presence of diabetes appears to double the odds of developing depression.47 The finding of depression was the single most important indicator of subsequent death in a group of diabetic patients admitted into hospital.48 Failure to recognize depression can be serious since it is a long-term, life-threatening, disabling illness and has a significant impact on quality of life.49 Depression may be associated with worsening diabetic control50 and decreased treatment compliance. In the Baltimore Epidemiological Project (1996), a 13-year follow-up of more than 3400 household residents (about one in seven was aged 65 years and over), major depressive disorder had an adjusted OR of 2.23 for predicting the onset of type 2 diabetes.51

Importance of Functional Evaluation

Functional evaluation of older people with diabetes mellitus using well-validated assessment tools is an essential step in the initial assessment process. Evaluation of functional status should be a multidisciplinary approach and comprise at least three main areas for measurement: physical, mental and social functioning. However, further evaluation with measures of self-care abilities and independent living skills (generally assessed by ADL tools) are also required. The benefits of functional assessment in the context of diabetes are indicated in Table 101.5.

Table 101.5 Benefits of functional assessment: diabetes-related.

Functional assessment is a primary component of comprehensive geriatric assessment (CGA), which is an essential methodology for geriatric medical practice.52 CGA is crucial at the initial assessment and helpful in planning care and rehabilitation and monitoring progress. CGA can be performed in many clinical and healthcare locations and not only involves a basic assessment of functional status but also includes various limited screening techniques, evaluation of social and medical problems, instigating initial treatment and ensuring follow-up. CGA and its variants (including in-home assessment packages) have been demonstrated to reduce mortality (by 14% at 12 months), increase the chance of remaining at home after referral (26% at 12 months), reduce hospital admissions (12% at 12 months), with gains in cognition and physical function having also been observed.53 Not all patients gain from this approach and targeting is required. Criteria for older subjects with type 2 diabetes who may derive benefit from comprehensive assessment methods with a measure of functional status are given in Table 101.6. A summary of the various assessment methods in common use is given elsewhere in this book. The authors do not advocate that all practitioners in Europe should adopt CGA as a routine part of their assessment processes, but suggest that functional assessment become a routine measure in older people with type 2 diabetes at diagnosis and at regular intervals thereafter.

Table 101.6 Criteria for targeting patients with type 2 diabetes for comprehensive geriatric assessment.

Treatment and Care Issues: Learning From the Literature

The major aims in the management of older people with type 2 diabetes involve both medical and patient-oriented factors (Table 101.7). An initial plan for the early evaluation of patients is reflected in Table 101.8, which should form a framework for instigating the appropriate treatment pathway. An important aim of risk assessment in the general population is to identify subclinical cardiovascular risk, which may be the principal cause of undetected functional impairment or frailty in older people. Coronary risk charts are often based on Framingham data54, 55 and can be used to identify either 5 or 10 year event rates, but it is important to note that cardiovascular risk data are generally based on populations of individuals up to a maximum age of 74 years only. In a large proportion of older people with type 2 diabetes, excess cardiovascular risk is evident and active intervention should be considered.

Table 101.7 Major aims in managing older people with diabetes.

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