Loss of taste and smell can influence the enjoyment of food and decrease motivation to eat and drink.
Such sensory losses occur naturally as a function of age (49) as well as with certain diseases, such as cancer.
Adding ready-to-use flavour enhancers containing monosodium glutamate (MSG) may improve dietary intake and thus reverse weight loss, improve immunity, functional status and quality of life (34,50,51).
When the thirst sensation is decreased, dehydration can occur.
Many elderly patients deliberately reduce their fluid intake to reduce their urine frequency, which may be increased due to glycosuria and prescribed diuretics.
The recommended minimum daily fluid intake is 1500 ml (approximately 7, 8 cups/ glasses), but this will be higher for patients with poorly controlled diabetes since urinary output is increased (52).
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SOCIAL FACTORS Eating is not just a feeding process, but an important social event.
Food choices and access to food can be affected by numerous factors including bereavement, immobility and isolation.
All can affect the motivation to eat and enjoy food.
The ability to shop and prepare meals decreases with age (16), with 30% of men and 50% of women reported as housebound or requiring assistance to shop when over 85 years of age (53).
The available and discretionary income may also fall with age.
It is therefore difficult for many elderly patients to follow a prescribed diabetic diet especially as many luncheon clubs, community meals, day centres and ready meals do not cater specifically for people with diabetes.
PHYSICAL FACTORS Functional limitations such as mobility and illness affect nutritional status.
Elderly people with diabetes have increased levels of disability and immobility that affect all aspects of daily living, including shopping, meal preparation and leisure activities (54).
Patients with diabetes are at an increased risk of a stroke and any resultant neurological deficit can lead to eating problems and malnutrition (55,56).
The most frequently encountered eating problems are hoarding food in the mouth, poor lip seal leading to leakage of food, dysphagia and chewing problems.
Careful observation at mealtimes, and assessment by a speech therapist if necessary, will enable identification of specific eating problems.
For some patients, eating in front of people can be a traumatic and embarrassing event, further reducing food intake.
PSYCHOLOGICAL AND COGNITIVE FUNCTION Any level of psychological or cognitive deficit may lead to a poor or erratic diet affecting both nutritional state and glycaemic control.
Memory lapses can result in missed meals and medication or an inadvertent repeated dose of some medications leading to, amongst other things, hypoglycaemia.
Cognitive function is also impaired in people with diabetes due to increased incidence of cerebrovascular disease and depression (57,58).
Psychological problems are both a predictor of mortality and of hospital admissions (59).
Food intake can be markedly reduced in the presence of dementia.
VOICES (Voluntary Organisations Involved in Caring in the Elderly Sector) produced a report in 1998 regarding the specific nutritional needs of elderly people with dementia (60).
Cognitive deterioration in patients with diabetes may be made worse by nutritional deficiencies (61) and poor glycaemic control.
Cognitive function
NUTRITIONAL MANAGEMENT OF THE ELDERLY 157
with documented improvements in problem solving, attention, concentration, memory and learning ability have been reported with better glycaemic control (10). Figure 10.1 summarises many of these factors and offers strategies for their treatment.
OTHER CONSIDERATIONS WHEN ADVISING OLDER PEOPLE WITH DIABETES
DELAYED GASTRIC EMPTYING Hyperglycaemia delays gastric emptying (62) as do multiple other factors, many of which remain poorly understood.
Physiological inhibitory pathways exist that control gastric emptying and involve small intestinal receptors that are stimulated by nutrients in the lumen of the gut.
Posture, meal size and meal composition all influence gastric emptying through activating these receptors.
Dietary fat empties at a slower rate than protein or carbohydrate and liquids empty faster than solids.
A modest degree of gastroparesis occurs with ageing.
However, this is much commoner in people with diabetes; upto half of all patients with long-standing diabetes (both Type 1 and 2) have some evidence of delayed gastric emptying (62).
Gastroparesis affects both glycaemic control as well as oral hypo- glycaemic drug absorption, and in elderly people may precipitate post-prandial events, which may lead to loss of consciousness and falls.
Delayed gastric emptying can be asymptomatic, making the diagnosis difficult.
Symptoms, if present, include nausea, vomiting and abdominal fullness.
However, none of these symptoms correlate well with gastric emptying.
Patients presenting with gastrointestinal symptoms, who already have diabetic complications, in particular autonomic neuropathy, are major candidates for this condition or other disorders of gut motility.
Hyper- glycaemia may contribute to these symptoms as it has been reported to increase the perception of sensations arising from the gut (63).
Delays in gastric emptying can reduce the rate of drug transit and slow the rate of absorption.
A few studies have been conducted in patients with diabetes that demonstrate a correlation between the absorption of glibenclamide and glipizide and gastric emptying time (62).
With drugs that have a long half-life and are given long-term, this effect would not be expected to lead to significant alterations in blood concentrations of the drug.
Gastric emptying can affect glycaemic profiles.
Rapid gastric emptying can cause glycaemic spikes and a worsening of control.
On the other hand, when gastric emptying is delayed a mismatch with the onset of hypoglycaemic drug action and glucose absorption can occur, leading to hypoglycaemia.
Figure 10.1. Taking steps to tackle eating problems NUTRITIONAL MANAGEMENT OF DIABETES MELLITUS
Source: Reproduced from the British Dietetic Association’s Nutrition Advisory Group for Elderly People (64).
NUTRITIONAL MANAGEMENT OF THE ELDERLY 159
The most successful treatment for gastroparesis remains pharmacological. Dietary advice should focus on preventing weight loss and malnutrition. Eating and drinking separately and advice encouraging small frequent meals and snacks can improve symptoms. Supplements may be needed if specific nutrients are deficient or malabsorption is present.
RISK OF HYPOGLYCAEMIA The risk of, and fear of, hypoglycaemia is a major reason why diabetes is undertreated in older people.
The Diabetes Control and Complications Trial in Type 1 diabetes and the UKPDS trial in Type 2 diabetes clearly demonstrated that secondary complications could be decreased by tight glycaemic control, but this increased the risk of hypoglycaemia (65,66).
Hypoglycaemia is a particular problem in older patients with Type 1 diabetes as hypoglycaemic awareness decreases with duration of diabetes and advancing age.
In addition, older patients with Type 2 diabetes treated with hypoglycaemic drugs are particularly prone to hypoglycaemia if dietary intake is variable.
General frailty, polypharmacy, renal impairment and frequent hospitalisations are all risk factors for hypoglycaemia (67).
Hypoglycaemic symptoms are frequently unrecognised and, when they are recognised, may not be treated appropriately.
There are no established glycaemic goals for the older patient.
Sinclair has recommended pre-meal targets of 6, 8 mmol/l and 7, 9 mmol/l at bedtime, with less stringent levels for individuals with recurrent hypoglycaemia (68).
The St Vincent Joint Task Force for Diabetes final report emphasises selecting glycaemic targets on an individual basis and focusing management goals on elevated lipids and blood pressure (69).
Dietary management on how to avoid hypoglycaemia is discussed in detail elsewhere in this book.
As for any hypoglycaemic episode, rapidly absorbed carbohydrate should be consumed, followed by longer lasting carbohydrate.
Education of elderly patients and their carers on how to avoid hypoglycaemia is important, and emphasis should be placed on regular meals and ensuring adequate carbohydrate with each meal.
MEDICATION The choice of a single oral agent for the elderly individual with Type 2 diabetes is made predominately on the basis of weight, clinical assessment of insulin resistance and renal function.
Lean patients with Type 2 diabetes are more likely to need an agent to increase their circulating insulin levels (e.g. sulphonylureas or insulin) while obese patients may require an agent to reduce insulin resistance (e.g. metformin or a glitazone).
Sulphonylureas with a long biological action, such as glibenclamide, increase the risk of hypoglycaemia in elderly people (70).
Reduced renal function delays
160 NUTRITIONAL MANAGEMENT OF DIABETES MELLITUS
the excretion of some active drug metabolites and increases the risk of hypoglycaemia.
Sulphonylureas with shorter biological actions, such as glicazide or the older tolbutamide (metabolised by the liver) are associated with less hypoglycaemia.
Metformin is effective in obese older patients as it indirectly increases insulin sensitivity, promotes weight loss and is not associated with hypoglycaemia when given as monotherapy.
Renal function should be monitored in patients taking metformin (71) and not used when renal impairment is present or if there is severe anorexia.
Age should not be a barrier to starting insulin and is often required for elderly patients with Type 2 diabetes, who can usually cope well with the new insulin pen devices (68).
Elderly people are at risk for drug, nutrient interaction, a problem which has been reviewed by Lewis et al. (72) and Roe (73).
Drugs can interfere with nutrient intake, absorption, metabolism and excretion.
Foods can interact with drugs, altering their absorption and action.
For example, bulking agents, such as methylcellulose, can decrease appetite by creating a feeling of fullness.
Metformin reduces vitamin B12 absorption, diuretics increase urinary loss of potassium and magnesium and warfarin can affect vitamin K metabolism.
Food in general may decrease the absorption and absorptive rate of aspirin, while fibre can specifically reduce the absorption of digoxin.
It is important to be aware of these interactions and to ensure sufficient intake of nutrients to prevent any potential nutritional deficiencies.
ACUTE INTERCURRENT ILLNESS As with any adult with diabetes who becomes ill, older people should be encouraged to take regular carbohydrate and sufficient drinks while continuing their medication.
As their appetite may be reduced, small frequent drinks may be more tolerable and acceptable.
Older people should be advised to prepare for illness by keeping suitable foods stored for such an eventuality, e.g. long-life or dried milk, tinned milk puddings, fortified drinks, tinned and dried foods, UHT fruit juice, porridge oats or other cereals, etc.