Full text of DOI:10.1093/gerona/56.1.M5

REVIEW ARTICLE
Copyright 2001 by The Gerontological Society of America
Journal of Gerontology: MEDICAL SCIENCES
001, Vol. 56A, No. 1, M5–M13
2
Diabetes in Elderly Adults
Graydon S. Meneilly and Daniel Tessier2
1
1Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, Canada.
2Division of Geriatric Medicine, Department of Medicine, University of Sherbrooke, Quebec, Canada.
Diabetes is common in the elderly population. By the age of 75, approximately 20% of the population are afflicted
with this illness. Diabetes in elderly adults is metabolically distinct from diabetes in younger patient populations,
and the approach to therapy needs to be different in this age group. Diabetes is associated with substantial mor-
bidity from macro- and microvascular complications. Several lines of evidence suggest that optimal glycemic con-
trol and risk factor modification can substantially reduce the risk of complications in elderly patients. In the past,
treatment options were limited. However, recent studies have delineated several new and exciting therapeutic op-
portunities for elderly patients with diabetes.
EPIDEMIOLOGY
A number of studies have carefully evaluated glucose
metabolism in middle-aged patients with type 2 diabetes (6).
These studies have shown that patients have several meta-
bolic abnormalities, including increased fasting hepatic glu-
cose production, altered glucose-induced insulin release, and
marked resistance to insulin-mediated glucose disposal. Re-
cently, investigators (7–9) have also carefully assessed the
metabolic changes in lean or obese older subjects with type
2 diabetes. In contrast with younger patients, hepatic glu-
cose production was within the normal range in elderly pa-
tients (Figure 2). Lean older patients with type 2 diabetes had
a marked impairment in glucose-reduced insulin secretion
(Figure 3), but relatively normal insulin-mediated glucose
disposal (Figure 4). It has recently been suggested that thin
elderly diabetics have a syndrome intermediate between
type 1 and 2 diabetes, which might properly be thought of as
type 1 1/2 diabetes (10). In contrast, obese older patients
have relatively normal glucose-induced insulin secretion
(Figure 3), but marked resistance to insulin-mediated glu-
cose disposal (Figure 4). Tumor necrosis factor ␣ (TNF-␣)
is a cytokine produced by adipocytes that is believed to con-
tribute to the insulin resistance seen in younger patients
with diabetes. Of interest, there is a strong correlation be-
tween TNF-␣ levels and insulin resistance in obese elderly
patients with diabetes (11), although the therapeutic rele-
vance of this finding is unclear. The previously described
data suggest that diabetes in elderly persons is metabolically
distinct and may require a different therapeutic approach
than is commonly applied to middle-aged patients.
Other metabolic defects have recently been defined in
elderly patients with diabetes. Glucose uptake in men occurs
by insulin-mediated and non-insulin–mediated mechanisms
(12). In normal subjects, approximately 50% of glucose up-
take after a meal occurs as a result of non-insulin–mediated
glucose uptake (NIMGU). In younger subjects with insulin-
resistant conditions, NIMGU may be responsible for an
even greater proportion of postprandial glucose disposal.
Studies that have evaluated non-insulin–mediated glucose
uptake in middle-aged patients with diabetes have produced
conflicting results (12). Recently, we demonstrated that non-
insulin–mediated glucose uptake was significantly impaired
Numerous studies have evaluated the incidence and prev-
alence of type 2 diabetes in the elderly population. The most
recent Health and Nutrition Survey, HANES III, suggests
that approximately 20% of the population develop diabetes
by the age of 75 (Figure 1) (1). At least half of these patients
are unaware they have the disease (2). The prevalence of di-
abetes is much higher in some ethnic groups, especially Na-
tive Americans, Hispanics, blacks, and Micronesians. Be-
cause elderly patients with diabetes are living longer and are
likely to use increasing amounts of scarce health care re-
sources in the next several decades, diabetes in aged adults
may ultimately prove to be the most important epidemic of
the 21st century.
PATHOGENESIS
There are several lines of evidence to suggest that type 2
diabetes in elderly adults has a strong genetic predisposition.
Elderly patients with a family history of diabetes are more
likely to develop the disease as they age (3). The prevalence
of diabetes is increased in certain ethnic groups, implying
that genetic factors play an important role. In elderly identi-
cal twins, the prevalence of diabetes is markedly increased
in siblings of affected patients (4). In addition, in sibling
pairs that are discordant for diabetes, nondiabetic siblings
clearly have evidence of disordered glucose metabolism.
Several other factors contribute to the high prevalence of
diabetes in the elderly population (5). There are a number of
age-related changes in carbohydrate metabolism (such as al-
terations in glucose-induced insulin release and resistance
to insulin-mediated glucose disposal) that interact with ge-
netic background to explain the progressive increase in the
incidence of diabetes with aging. Lifestyle factors are also
important. Individuals who are obese (especially if the dis-
tribution of body fat is central), who consume diets that are
high in saturated fat and low in complex carbohydrates, or
who are inactive are more likely to develop diabetes as they
age. Lower testosterone levels in men and higher values in
women also appear to be risk factors for the development of
diabetes in elderly persons, although the mechanistic signif-
icance of these abnormalities is uncertain.
M5

M6
MENEILLY AND TESSIER
Figure 1. Prevalence of diabetes in men and women in the U.S. population, based on the Health and Nutrition Survey, HANES III. Reprinted
with permission from Harris and colleagues (1).
in elderly patients with diabetes (13). Interventions that may
enhance NIMGU are currently being tested in clinical trials,
and these interventions may ultimately prove to have impor-
tant therapeutic relevance to aged adults.
It is well known that diseases characterized by insulin resis-
tance (such as hypertension, obesity, and type 2 diabetes) are
associated with endothelial dysfunction and an increased in-
cidence of atherosclerosis (14). Insulin is known to stimu-
Figure 2. Fasting hepatic glucose production in relation to fasting
glucose values in elderly controls and patients with diabetes.
Figure 3. Glucose-induced insulin release in elderly controls and
patients with diabetes.

DIABETES IN ELDERLY ADULTS
M7
PRESENTATION AND CLINICAL FEATURES
One half of older persons with diabetes are unaware they
have the illness, suggesting that symptoms of hyperglyce-
mia are rarely present in this patient population (5). This
may be because the renal threshold for glucose increases with
age, so that no sugar is spilled into the urine until the glu-
cose level is markedly elevated. In addition, because thirst
is impaired with normal aging, polydipsia is unlikely in el-
derly patients with diabetes, even if they are hyperosmolar as
a result of marked hyperglycemia. If symptoms do occur, they
are generally nonspecific (confusion, failure to thrive, in-
continence, etc.). Often, diabetes presents for the first time
in an elderly person who is hospitalized with a complication
that may be related to diabetes, such as a myocardial infarc-
tion or a stroke. In frail elderly nursing home patients, non-
ketotic hyperosmolar coma may be the first sign of diabetes.
Several unique syndromes occur in elderly patients with
diabetes (5). Diabetic neuropathic cachexia presents with
weight loss, depression, and painful peripheral neuropathy,
and generally is resolved without specific treatment in a few
months. Diabetic amyotrophy occurs almost exclusively in
older men with diabetes. Malignant otitis externa, a necro-
tizing infection usually caused by pseudomonas, occurs pri-
marily in elderly patients with diabetes. The papillary ne-
crosis that can occur with pyelonephritis develops primarily
in elderly patients with diabetes. Spontaneously resolving
intradermal bullae of the feet and the painful limitation of
shoulder movements occur more commonly in elderly pa-
tients with diabetes. Finally, diabetes in elderly persons has
been associated with an increased risk of accidental hypo-
thermia.
Community-dwelling elderly patients with diabetes are
less obese and more likely to be hypertensive when com-
pared with younger patients with this illness (5). When
compared with community-dwelling elderly persons with
diabetes, elderly nursing home patients with diabetes are
more likely to be treated with diet, less obese, less likely to
be treated with insulin, and have a higher incidence of
macro- and microvascular complications and skin infec-
tions. Finally, when compared with nursing home residents
without diabetes, elderly nursing home patients with diabe-
tes have a higher incidence of infections and micro- and
macrovascular complications.
Figure 4. Insulin-mediated glucose disposal in elderly controls and
patients with diabetes.
late blood flow by an endothelium-dependent mechanism.
Insulin-mediated vasodilation may be impaired in younger
subjects with diseases characterized by insulin resistance,
although the data are controversial. It has also been implied
that insulin-mediated blood flow may be an important com-
ponent of insulin-mediated glucose uptake, although studies
in normal subjects and younger patients with diseases char-
acterized by insulin resistance have again produced conflict-
ing results. Recently, we demonstrated that insulin-mediated
blood flow is impaired with normal aging, and there is an
even greater impairment in this parameter in elderly patients
with diabetes (9,15). Although the role of the alteration in in-
sulin-mediated vasodilation in the insulin resistance that
occurs with aging and diabetes is uncertain, it is clear that
reduced insulin-mediated vasodilation is a marker of endo-
thelial dysfunction in elderly patients with diabetes. Further
studies are needed to determine whether enhancing insulin-
mediated vasodilation will alter insulin resistance, improve
endothelial function, or reduce the risk of atherosclerotic
events in this population.
Autoimmune phenomena are an important contributing
factor to the insulin deficiency that occurs in younger patients
with type 1 diabetes (5). Autoimmune factors may also have
a role to play in the insulin deficiency that occurs in lean el-
derly patients with diabetes, but the data are conflicting (5,16–
COMPLICATIONS
Diabetes is the sixth most common cause of death
among elderly adults. However, its role in mortality in the
elderly population is probably understated, because when
patients die of cardiovascular causes, diabetes is often not
listed as a contributing cause of death (5,19,20). The prin-
cipal cause of death in elderly patients with diabetes is car-
diovascular disease, and these patients have nearly twice
the mortality rate of age-matched controls without diabetes.
It has been estimated that in patients who develop diabetes
over the age of 65 years, life expectancy is shortened by at
least 4 years (19). Mortality in elderly patients with diabe-
tes is strongly correlated with long-term variability of
plasma glucose and Hgb A1C values (5,21,22). People with
diabetes have a poorer quality of life and a higher fre-
quency of chronic disease than do age-matched controls
1
8). Further investigations are required to resolve this issue.
Molecular abnormalities that occur in elderly patients
with diabetes have not been fully elucidated (5). The glu-
cokinase gene is the glucose sensor of the ␤ cell. Theoreti-
cally, alterations in this gene could explain defects in insulin
secretion, but it is not clear whether the function of this gene
is impaired in older people with diabetes. Insulin-receptor
tyrosine kinase activity in skeletal muscle has been reported
to be altered in elderly patients with diabetes and insulin re-
sistance, but it is uncertain whether this is the cause or the
result of the elevated glucose levels in these patients.

M8
MENEILLY AND TESSIER
without diabetes, and diabetes is one of the strongest pre-
dictors of functional decline in longitudinal studies (5,23–
rather than human insulin, but these data are controversial
(30,31).
2
6). Finally, elderly patients with diabetes use almost twice
Elderly patients with diabetes have a higher incidence of
depression and impaired cognitive function when compared
with age-matched controls without diabetes (5). Depression
in elderly patients with diabetes is a strong predictor of hos-
pitalization and death (32). The changes in cognitive and af-
fective function are closely correlated with lipid, blood pres-
sure, and Hgb A1C values, and recent studies suggest that
improved glycemic control may enhance cognition and
mood in this patient population (5). Diabetes in elderly per-
sons is clearly a risk factor for vascular dementia and may
also be a risk factor for Alzheimer’s disease, although the
latter is controversial (33).
as many inpatient and outpatient resources as elderly peo-
ple without diabetes (5).
The risk of macrovascular events (cardiovascular disease,
cerebrovascular disease, and peripheral vascular disease) is
doubled in elderly patients with diabetes when compared
with controls (5). The risk of these events is related to dura-
tion of diabetes, Hgb A1C values, and the presence of tradi-
tional risk factors such as smoking, hypercholesterolemia,
and hypertension (5). Although randomized trials are re-
quired to definitively address this issue, the data imply that
risk-factor modification and improved glycemic control will
result in improved outcome in elderly persons (5).
The risk of microvascular complications is also increased
in elderly persons, and, again, there is a strong correlation
between the risk of these complications and Hgb A1C, dura-
tion of diabetes, hypertension, and hyperlipidemia (5). Al-
though no randomized controlled trials have been con-
ducted in this regard, the previously described data again
suggest that improved glycemic control and risk-factor
modification may be of value.
The risk of severe or fatal hypoglycemia associated with
the use of oral agents or insulin increases exponentially with
age (5,27). This increased risk of hypoglycemia in elderly
persons is related, in part, to reduced responses of glucagon,
the most important counter-regulatory hormone (Figure 5).
Because of this glucagon deficiency, elderly subjects are
critically dependent on epinephrine to prevent hypoglyce-
mia (28). Other contributing factors to the high prevalence
of hypoglycemia include lack of knowledge of the warning
symptoms of hypoglycemia and reduced awareness of auto-
nomic warning symptoms, even when the patient has been
educated regarding the nature of these symptoms (5). When
elderly subjects do experience symptoms of hypoglycemia,
the symptoms tend to be less intense and more nonspecific
DIAGNOSIS
The diagnostic criteria of the American Diabetes Associ-
ation (ADA) for diabetes mellitus have recently been re-
vised as follows (34): Symptoms of diabetes plus a casual
(any time of day without regard to time since last meal)
plasma glucose value of Ն11.1 mmol/l (the classic symp-
toms of diabetes include fatigue, polyuria, polydipsia, and
unexplained weight loss); a fasting plasma glucose value of
Ն7.0 mmol/l (fasting is defined as no caloric intake for at
least 8 hours); or a plasma glucose value in the 2-hour sam-
ple of the oral glucose tolerance test (OGTT) of Ն11.1
mmol/l. The test should be performed using a load of 75 g
of anhydrous glucose.
The criteria were changed because they lacked sufficient
sensitivity. In addition, the values used for diagnosis were
not concordant between fasting glucose values and the
OGTT. The fasting glucose level used in the earlier criteria
(7.8 mmol/l) defined a greater degree of hyperglycemia and
a greater risk of macrovascular events than the 2-hour glu-
cose value from the OGTT that was diagnostic of diabetes
(11.1 mmol/l). Because a substantial number of elderly pa-
tients have undiagnosed diabetes, and these patients appear
to have an increased incidence of macrovascular events, the
current criteria recommend that a fasting glucose value be
performed every 3 years in elderly patients at low risk for
diabetes and yearly in patients at high risk. Patients at high
risk include those with obesity, hypertension, ethnicity,
family history, or the presence of complications commonly
associated with diabetes. If the efforts to standardize Hgb
A1C measurements come to fruition, this test may ulti-
mately supplant the fasting glucose value as the preferred
screening method (35). In addition, some studies suggest
that substantial numbers of elderly subjects have fasting
glucose values Ͻ7 mmol/l, but also have a diabetic glucose
tolerance test, and these subjects have an increased risk of
macrovascular events when compared with nondiabetic
controls (36–38). It is possible that OGTT may also be con-
sidered in the future for screening, particularly in high-risk
patients or subjects with impaired fasting glucose levels
(
29). It has been suggested that hypoglycemic awareness
may be enhanced in older people treated with animal insulin
(
6.1–7 mmol/l). Further studies are needed to determine the
optimal screening method in aged adults.
TREATMENT GOALS
All clinicians agree that blood glucose should be con-
trolled well enough in elderly patients to prevent symptoms
Figure 5. Glucagon responses to hypoglycemia in healthy young,
healthy elderly, and elderly patients with diabetes.

DIABETES IN ELDERLY ADULTS
M9
associated with hyperglycemia. The UK Prospective Diabe-
tes Group (39) demonstrated that control of diabetes in mid-
dle-aged subjects reduces the risk of microvascular, and
possibly macrovascular, complications. As yet, there are no
data from randomized controlled trials in elderly subjects to
determine the level of glycemic control in this patient popu-
lation that maximizes benefit but minimizes the risks of ther-
apy, in particular, hypoglycemia. However, numerous
prospective epidemiologic studies have shown a strong cor-
relation between Hgb A1C values and the risk of complica-
tions in this patient population (5). If improved glycemic
control alters the risk of complications and associated func-
tional disability in aged adults, this intervention could have
a profound effect on the quality of life for elderly persons.
Recent cost-benefit analyses have called into question the
cost effectiveness of aggressive glycemic control in aged
adults (40–42). Before these analyses are widely applied by
health-policy makers as a justification for a nonaggressive
approach to the care of the elderly diabetic, the assumptions
underlying these studies must be critically evaluated (5). The
analyses were based entirely on data from investigations in
younger patient populations, the authors only assessed the
benefits of control for patients who did not have complica-
tions to begin with, and only microvascular complications
were considered. Diabetics tend to engender increased costs
to the health care system for non-diabetes–related illnesses
ing homes often have few guidelines for the care of elderly
residents with diabetes, and knowledge of diabetes tends to
be relatively poor among the staff of these facilities. Im-
proved outcomes for elderly nursing-home patients can oc-
cur as a result of educational programs for the staff.
Since elderly diabetic persons with conventional risk fac-
tors have an increased risk of vascular complications, risk-
factor modification may be of benefit. Recent large-scale
studies (46,47) suggest that treatment of isolated systolic
hypertension will reduce the risk of complications in these
patients independent of glycemic control. Studies (48,49)
also suggest that in elderly patients without diabetes or pa-
tients with type 2 diabetes in their 60s who have evidence of
cardiovascular disease, lipid-lowering therapy reduces the
risk of subsequent cardiovascular events. The Heart Out-
comes Prevention Evaluation, or HOPE, Study (50) showed
that angiotensin-converting enzyme inhibitors reduce the
risk of macrovascular complications and death in older pa-
tients with diabetes and one other risk factor independent of
the effects of these drugs on blood pressure). The previously
described data argue for a more aggressive approach to risk-
factor modification in elderly persons than has previously
been applied.
Diet and Exercise
There are few original studies of dietary interventions in
elderly patients with diabetes (5). It appears that elderly pa-
tients with this illness avoid simple sugars but do not adhere
to current dietary recommendations regarding fat and fiber
composition. A dietary intervention that results in weight
loss has been found to improve glycemic control in ambula-
tory obese elderly patients with diabetes. However, diabetic
diets complicate the care and increase the cost of looking af-
ter frail elderly nursing-home patients, and these diets do
not appear to significantly improve glycemic control in this
patient population. Elderly patients with diabetes are at risk
for deficiency of trace elements, and magnesium and zinc
supplementation results in improvements in glycemic con-
trol. Hyperglycemia in elderly patients with diabetes is as-
sociated with increased oxidative stress (51). Small-scale
studies have demonstrated that supplementation with anti-
oxidant vitamins (C and E) may improve glycemic control
(5). Unfortunately, the effect of exercise programs on glyce-
mic control in elderly patients with diabetes has been in-
completely assessed, and the results of the studies that have
been done are conflicting (5). Clearly, further investigations
are needed to evaluate the role of dietary and exercise inter-
ventions in the management of diabetes in the elderly popu-
lation.
(
respiratory infections, etc.). The improved control of diabetes
has been found to reduce costs in this area for middle-aged
patients, and the potential benefits of improved control on
costs for non-diabetes–related illnesses were not evaluated
in these analyses. In addition, it has been demonstrated that the
assumptions underlying traditional cost-benefit analysis tend to
discriminate against elderly populations (43). Ultimately,
properly randomized controlled trials will need to be con-
ducted to determine the benefits and cost of optimal glycemic
control in elderly persons. Based on the evidence available,
we have developed guidelines for the control of diabetes in
elderly persons as follows:
Goals of therapy for the healthy elderly patient with diabe-
tes: a fasting plasma glucose level of Ͻ7.0 mmol/l; a 2-hour
plasma glucose value of Ͻ11.0 mmol/l; and Hgb A1C values
of Ͻ15% above the upper limit of normal.
Goals of therapy for the frail elderly patient with diabetes:
a fasting plasma glucose level of Ͻ10 mmol/l; a 2-hour
plasma glucose value of Ͻ14 mmol/l; and Hgb A1C values
of Ͻ40% above the upper limit of normal.
Clinicians will need to modify the guidelines for each in-
dividual patient based on their comorbidity and functional
status.
␣
-Glucosidase Inhibitors
THERAPEUTIC OPTIONS
␣-Glucosidase inhibitors act by inhibiting the digestion and
According to current ADA guidelines, diabetes in elderly
persons is undertreated (44,45). Because elderly patients
with diabetes are often complicated as a result of multiple
pathologies, social factors, and polypharmacy, a team ap-
proach to management is essential. Multidisciplinary pro-
grams, particularly if they involve family members caring
for the patient, have been shown to result in improved com-
pliance with therapy and better glycemic control (5). Nurs-
absorption of simple sugars from the gastrointestinal tract.
The major side effects of these drugs are gastrointestinal,
particularly flatulence and diarrhea. A recent randomized
controlled trial of glyburide versus the ␣-glucosidase inhibi-
tor miglitol in elderly patients with diabetes demonstrated
that miglitol reduced Hgb A1C by about 0.5%, whereas gly-
buride reduced Hgb A1C by about 1%. However, the pa-
tients who were treated with glyburide had more weight gain,

M10
MENEILLY AND TESSIER
a higher frequency of hypoglycemia, and an increased inci-
dence of cardiovascular events (52). In a recent randomized
multicenter trial of the ␣-glucosidase inhibitor acarbose in
obese elderly patients with diabetes, acarbose reduced Hgb
A1C by about 0.8% when compared with the placebo and
also resulted in an improvement in insulin sensitivity (53).
rosiglitazone may be a beneficial adjunct in elderly patients
who have suboptimal glycemic control, despite insulin re-
quirements of Ͼ50 units per day.
Sulfonylureas
The absorption and elimination of glyburide is impaired
with age, and elderly subjects appear to have enhanced insulin
responses to the drug as well (5). This may explain, in part,
the age-related exponential increase in the frequency of se-
vere or fatal hypoglycemia with this drug. The kinetics of
other sulfonylureas do not appear to alter importantly with
age (5). In our opinion the use of chlorpropamide is rela-
tively contraindicated in elderly persons because this drug is
associated with an increased frequency of hypoglycemia,
and can interact with multiple drugs and cause an antabuse
effect and syndrome of inapproriate secretion of antidiuretic
hormones, or SIADH. The risk of hypoglycemia associated
with sulfonylureas in aged adults appears to be reduced with
tolbutamide, gliclazide, and, possibly, glipizide (57). In ad-
dition to the type of sulfonylurea, other potential risk factors
for hypoglycemia with these drugs in elderly persons in-
clude black race, multiple medications, male sex, renal dys-
function, and ethanol consumption (27,58). Sulfonylureas
should be considered as a first-line therapy in lean elderly
patients with diabetes.
␣-Glucosidase inhibitors are useful drugs as primary ther-
apy for elderly patients with modest fasting hyperglycemia,
especially if they are obese. They can also be used in pa-
tients taking other oral agents to enhance glycemic control.
Metformin
Metformin is currently the only biguanide available in
North America. Aging does not appear to be a risk factor for
lactic acidosis with metformin, provided that careful atten-
tion is paid to the contraindications for this drug (significant
liver, renal, and cardiac disease) (5). Limited nonrandom-
ized clinical studies suggest that the drug is safe and effec-
tive as monotherapy in obese older people (5). A recent ran-
domized controlled trial demonstrated that metformin was
also effective when added to glyburide in poorly controlled
elderly patients with diabetes. In this study, Hgb A1C was
reduced by approximately 1.6%, without a significant in-
crease in the risk of hypoglycemic events (54). In our view,
metformin is an ideal drug for first-line therapy of obese
older patients, because it increases insulin sensitivity, as-
sists with weight loss, reduces lipid levels, and rarely causes
hypoglycemia. In addition, it is a useful adjunct for patients
who are inadequately controlled on maximum doses of sul-
fonylureas.
Insulin
Elderly subjects often make errors when trying to mix in-
sulin on their own. The accuracy of insulin injections has
been shown to be improved in older patients when they are
treated with premixed insulin (5). Small-scale studies sug-
gest that as long as a premixed insulin is used, the portion of
regular to long-acting insulin in the mixture (i.e., 50:50 vs
30:70) does not significantly alter glucose or insulin levels
(59). Due to compliance problems in older individuals, some
clinicians have recommended using one injection of insulin
per day. However, hypoglycemia appears to occur more
commonly with one injection rather than two daily injec-
tions in this patient population. One study (60) suggested
that a combination of a sulfonylurea with insulin is probably
more effective than the same dose of insulin alone in elderly
patients. However, another study (61) failed to show a dif-
ference from the efficacy point of view between two doses
of insulin, one dose of insulin at bedtime plus sulfonylureas,
compared with one dose of insulin at breakfast plus sulfo-
nylureas. In this latter study, weight gain was comparable
between groups. Some differences between regimens may
have been masked because one third of the patients who
were started on one dose of insulin daily needed a second
injection to control glycemia. No studies have evaluated the
effectiveness of bedtime insulin along with daytime met-
formin in elderly persons. Our clinical experience suggests
that this strategy is effective in some patients who are reluc-
tant to inject insulin twice a day. We have also had exten-
sive clinical experience with the use of metformin in elderly
patients with diabetes treated with bid insulin. In obese pa-
tients, this combination appears to reduce weight gain asso-
ciated with insulin treatment, reduce insulin requirements,
and improve glycemic control. To date, no studies have
Thiazolidinediones
Drugs in this class improve glycemic control by ennhanc-
ing peripheral insulin sensitivity. Troglitazone was the first
drug of this type released for clinical use. This drug was re-
cently removed from the market because of concerns re-
garding hepatic toxicity. A randomized controlled trial of
troglitazone in elderly patients with diabetes found that the
drug was safe if patients were carefully monitored for he-
patic toxicity. Troglitazone resulted in significant improve-
ments in insulin sensitivity and glycemic control (55). Two
more drugs in this class have recently been released for use.
There are no data yet available on the effect of pioglitazone
in elderly patients. The kinetics of rosiglitazone are not sig-
nificantly altered in elderly patients (56). Pooled data on
elderly subjects from the clinical trials that have been done
with rosiglitazone have recently been published in abstract
form (57). Rosiglitazone appears to be as effective in older
patients as in younger patients and results in an approximate
1
.5% reduction in Hgb A1C. Hepatic toxicity has not been
reported in elderly subjects, although all elderly subjects who
are started on rosiglitazone should have liver function tests
monitored regularly until further studies are forthcoming. The
incidence of edema and anemia was substantially higher in
elderly patients than in middle-aged patients treated with
this drug, and volume status and blood count will need to be
carefully monitored in patients started on rosiglitazone.
Rosiglitazone can be a useful first-line therapy in obese el-
derly patients, particularly for those patients who cannot tol-
erate metformin or have a contraindication to it. In addition,

DIABETES IN ELDERLY ADULTS
M11
evaluated the effect of lispro insulin in the treatment of dia-
betes in elderly patients.
release and reduce appetite in middle-aged patients with di-
abetes. Recent data from our laboratory suggest that GLP-1
maintains its ability to enhance glucose-induced insulin re-
lease in elderly patients and may also increase insulin sensi-
tivity and NIMGU (G.S. Meneilly and D. Elahi, unpub-
lished observations). Long-term clinical studies are required
to determine the role of this peptide in the therapy of diabe-
tes in aged adults. No data are currently available on the use
of pramlintide in aged adults.
Other Drugs
Repaglinide is a nonsulphonylurea drug that has a distinct
-cell binding profile and stimulates insulin secretion from
␤
the ␤ cell by a mechanism similar to that of sulphonylureas.
The potential advantage of this drug is that it has a rapid on-
set and very short duration of action. As a result, it is felt to
be of value because it results in a more physiologic insulin
profile and because it can be given just before a meal in pa-
tients who tend to have irregular eating patterns. In addition,
in younger patient populations, repaglinide has been associ-
ated with a lower frequency of hypoglycemic events when
compared with conventional sulphonylureas, presumably
because of its shorter duration of action. The kinetics of repag-
linide are not altered with age (62). Data on elderly subjects
from the clinical trials that have been done with this drug
has been published in abstract form (63). The drug resulted
in a similar change in fasting glucose and Hgb A1C values
in middle-aged and elderly subjects, suggesting that it has
similar efficacy in each age group. In addition, when com-
pared with younger patients with diabetes, elderly patients
treated with repaglinide had a similar frequency of hypogly-
cemic events, suggesting that this drug may be associated
with a lower frequency of hypoglycemia in elderly persons
than conventional sulfonylureas. Pending the results of
properly randomized controlled trials in the elderly popula-
tion, repaglinide may be considered for elderly patients who
have irregular eating habits, or have frequent hypoglycemic
events on conventional sulfonylureas. These potential bene-
fits must be balanced against the cost of the new drug and
compliance problems that could result from having to take
the drug three times a day.
Monitoring Glycemic Control
Because the renal threshold for glucose increases with age,
urine glucose testing is not reliable in aged adults. Most
studies have found that elderly patients can successfully be
taught to monitor blood sugar at home, and such monitoring
does not alter their quality of life. Hgb A1C is the standard
measure of long-term (2–3 mo) glycemic control in this pa-
tient population, although serum fructosamine can be used
to measure changes in glycemic control over a shorter pe-
riod (2–3 wk) (66,67).
CONCLUSIONS
Because of the dramatic increase in its prevalence, diabe-
tes in the elderly population may ultimately prove to be the
most important epidemic of the 21st century. Fortunately,
our increased understanding of the pathogenesis and treat-
ment of this illness should allow us to improve the outcome
of the large numbers of elderly patients that will be afflicted
with this illness.
Acknowledgments
This research was supported by the Canadian Diabetes Association, the
Canadian Institutes of Health Research, the Allan McGavin Geriatric En-
dowment of the University of British Columbia, and the Jack Bell Fund at
Vancouver Hospital.
Depression is common in older people with diabetes. A
recent randomized controlled trial (64) demonstrated that
fluoxetine can assist with weight loss and improve glycemic
control in obese elderly patients with diabetes. This drug
should be considered for therapy of depression in obese elderly
patients with diabetes, particularly if they are in need of im-
proved glycemic control. Because fluoxetine has a very
long half life, caution should be used when administering
this drug to older patients, since excessive weight loss could
occur before the drug is cleared from the system. For this
reason, fluoxitene should never be given to lean elderly pa-
tients with diabetes. Orlistat is the first of a new class of an-
tiobesity agents, the lipase inhibitors, which have been de-
veloped for the long-term management of obesity. This drug
acts by selectively inhibiting the absorption of dietary fat.
Limited data from studies in middle-aged patients with type
Address correspondence to Dr. G.S. Meneilly, Room S 169, Vancouver
Hospital and Health Sciences Centre, UBC Site 2211, Wesbrook Mall,
Vancouver, BC V6T 2B5, Canada. E-mail: meneilly@interchange.ubc.ca
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Received June 30, 2000
Accepted September 6, 2000
Decision Editor: John E. Morley, MB, BCh