Glucose Targets Using Continuous Glucose Monitoring Metrics in Older Adults With Diabetes: Are We There Yet?

Abstract

The older population is increasing worldwide and up to 30% of older adults have diabetes. Older adults with diabetes are at risk of glucose-related acute and chronic complications. Recently, mostly in type 1 diabetes (T1D), continuous glucose monitoring (CGM) devices have proven beneficial in improving time in range (TIR glucose, 70-180 mg/dL or glucose 3.9-10 mmol/L), glycated hemoglobin (HbA1c), and in lowering hypoglycemia (time below range [TBR] glucose <70 mg/dL or glucose <3.9 mmol/L). The international consensus group formulated CGM glycemic targets relating to older adults with diabetes based on very limited data. Their recommendations, based on expert opinion, were aimed at mitigating hypoglycemia in all older adults. However, older adults with diabetes are a heterogeneous group, ranging from healthy to very complex frail individuals based on chronological, biological, and functional aging. Recent clinical trial and real-world data, mostly from healthy older adults with T1D, demonstrated that older adults often achieve CGM targets, including TIR recommended for non-vulnerable groups, but less often meet the recommended TBR <1%. Existing data also support that hypoglycemia avoidance may be more strongly related to minimization of glucose variability (coefficient of variation [CV]) rather than lower TIR. Very limited data are available for glucose goals in older adults adjusted for the complexity of their health status. Herein, we review the bidirectional associations between glucose and health status in older adults with diabetes; use of diabetes technologies, and their impact on glucose control; discuss current guidelines; and propose a new set of CGM targets for older adults with insulin-treated diabetes that are individualized for health and living status.

Introduction

The older adult population is increasing worldwide due to a longer life expectancy and advancement in medical therapies. ¹ Up to 30% of older adults have diabetes.^1,2

Older adults with type 1 diabetes (T1D) and many with type 2 diabetes (T2D) are treated with insulin or insulin secretagogues. These medications are associated with risk of hypoglycemia. Older adults have a greater risk of impaired awareness of hypoglycemia (IAH) ³ and report hypoglycemic symptoms less frequently. ⁴ Episodes of hypoglycemia are associated with high burden of diabetes distress both for those living with diabetes and their caregivers, ⁵ a high risk of emergency room visits and hospitalization,^6,7 and high healthcare costs. ⁸

Older adults with diabetes represent a heterogeneous population with a wide range in their chronologic, biological, functional, and psychosocial statuses, all of which may impact diabetes self-care and hypoglycemia risk. In acknowledgment of this heterogeneity, the American Diabetes Association (ADA) recommendations reflect that a “one-size-fits-all” approach for glucose targets in older adults based on chronological age may be inappropriate and that these targets should reflect the patient’s health status. ⁹

Use of continuous glucose monitoring (CGM) has been shown to improve glycemic control and reduce the risk of hypoglycemia.^10,11 Evidence suggests that this benefit extends to older adults.^{12 -14} As with glycated hemoglobin (HbA1c) levels, it became apparent that there was a need to establish a set of glucose targets pertinent to this new technology to guide clinicians and researchers. In 2019, an international consensus panel published a set of standardized CGM targets. ¹⁵ At the time the consensus guidelines were formulated, the data on CGM relating to older adults with diabetes were very limited and the recommendations, based on expert opinion, rightly focused on mitigation of hypoglycemia for all older adults. However, these guidelines did not address the inherent heterogeneity of the older population living with diabetes.

Since the development of such guidelines, more data have become available on the use of CGM in older adults with diabetes on insulin, which suggest that an individualized approach for CGM metrics in older adults based on health status may be more appropriate. In this article, we review the current CGM consensus guidelines and the current evidence on CGM and CGM-related technologies in the older population with diabetes. Finally, we propose a new set of CGM targets for older adults with insulin-treated diabetes that are individualized for health and living status.

Current Consensus Guidelines on CGM Metrics in Older Adults

The 2019 international consensus panel of diabetes experts, including individuals with diabetes, clinicians, and researchers, developed standardized targets for research and clinical practice. ¹⁵ The objective of the consensus was to define CGM glucose ranges for hypoglycemia (time below range [TBR]), time in range [TIR]) and hyperglycemia (time above range [TAR]), and the amount of time to spend in each of these defined ranges. ¹⁵

At that time, available data on CGM metrics in older adults were very limited. In comparison with the general diabetes population, the recommendations for older adults appropriately have much tighter goals for TBR, with the goal of avoiding sensor glucose <54 mg/dL (<3 mmol/L) and aiming for a sensor glucose <70 mg/dL (<3.9 mmol/L) only <1% compared with 4% in the adult healthy population with diabetes. Older adults with diabetes have an increased rate of IAH ³ and the gap between glycemic thresholds at which adrenergic and neuroglycopenic symptoms occur is narrowed significantly even in the non-frail older adult. ¹⁶ Thus, TBR (<70 mg/dL or <3.9 mmol/L), was modified by the consensus group to provide warning time to older adults to address impending hypoglycemia.

In addition, the consensus group also recommended a reduction in glycemic variability (coefficient of variation [CV]) to <33%, which was more stringent than the target for the mainstream of 36%. ¹⁵ ,^{17 -19} The purpose of the reduction in CV was to mitigate the associated increased risk of hypoglycemia with increasing glycemic variability. This risk was demonstrated in a large cohort of older adults with T1D where CV, rather than HbA1c, correlates with the time spent in hypoglycemia ²⁰ (Figure 1, panel A).

Figure 1.

Examples of discrepancy among glycemic metrics as time in range (TIR), time below range (TBR), and time above range (TAR) in panel A: Aggregated data of 130 older adults with T1D (modified from Toschi et al ²⁰ ) stratified by glycemic variability (CV% ≤36% and CV >36%). The numbers in bars are percentages of the daily time in respective ranges. Older adults with CV ≤36% have less %TBR and greater %TIR compared with older adults with greater glycemic excursions (CV >36) with higher %TBR and %TAR, despite similar HbA1c. Panels B and C: show ambulatory glucose profile (AGP) of two illustrative cases of two older adults with similar %TIR, although with different %TBR, %TAR, and CV.

Abbreviations: CGM, continuous glucose monitoring; CV, coefficient of variation; GMI, glucose management indicator; HbA1c, glycated hemoglobin.

Conversely, the consensus group made the TIR goal for glucose level between 70 and 180 mg/dL (3.9-10 mmol/L) less stringent at >50% compared with >70% for the general population. The proposed relaxation in goal for TIR was likely to reflect the current ADA guidelines in older adults based on their health status, whereby a higher HbA1c and fasting and post-meal glucose level is recommended as a way to avoid hypoglycemia. ⁹

The goal for time spent in hyperglycemia, reflected by TAR was also increased to <50% time >180 mg/dL (>10 mmol/L) compared with <25% in the general population, and time spent >250 mg/dL (>13.9 mmol/L) was increased to <10% compared with <5% in the general population. However, in the older population, an increase in TAR can increase the risk of dehydration, hospital admission, and increase in mortality^21,22 (Table 1). In addition, there is evidence that liberalization of HbA1c may not protect against the risk of hypoglycemia in the older population,^5,23 while increasing time spent in hyperglycemia ⁶ (Figure 1, panels B and C).

Table 1.

Risk Factors for Hypoglycemia and Hyperglycemia and Acute and Chronic Complication in Older Adults With Diabetes.

	Risk factors	Acute complications	Chronic complications
Hypoglycemia	• Duration of diabetes • Living alone • No or low residual C-peptide level • Impaired awareness of hypoglycemia • Diabetes complications and comorbidities • (eg, CKD, poor vision, and neuropathy) • Cognitive dysfunction • Frailty/reduced mobility • Recent hospitalization	• Impaired cognition • Imbalance, falls, and injuries • Post-hypoglycemia, hyperglycemia, for example, due to overtreatment of hypoglycemia • Nausea or vomiting from glucagon • Phlebitis or thrombosis from IV glucose • Worse mental well-being, for example, fear of hypoglycemia • Sleep disturbance • Epileptic seizures • Coma • Death	• Falls, accidents, and related injuries (eg, fractures) • Myocardial ischemia • Cardiac QT prolongation and arrhythmias • Stroke • Impaired awareness of hypoglycemia
Hyperglycemia	• Duration of diabetes • Living alone • No or low residual C-peptide level • Impaired awareness of hypoglycemia • Diabetes complications and comorbidities • (eg, CKD, poor vision, neuropathy) • Cognitive dysfunction • Frailty/reduced mobility • Recent hospitalization	• Dehydration • Hypotension • Polyuria/urinary incontinence • Impaired cognition • Increased risk of infection and slower recovery • Impaired wound healing • Imbalance, falls, and injuries • Weight loss • Sarcopenia/frailty • Increased risk of thrombosis • Electrolyte imbalance, for example, low K, low Mg • DKA and/or HHS • Coma • Death	• Macrovascular complications: (CVD, cerebrovascular disease, and PVD) • Microvascular complications: (retinopathy, CKD, and peripheral + autonomic neuropathy) • Cataracts • Dementia • Metabolic dysfunction–associated • Steatotic liver disease • Periodontal disease

Abbreviations: CKD, chronic kidney disease; CVD, cardiovascular disease; DKA, diabetic ketoacidosis, K, potassium; IV, intravenous; HHS, hyperosmolar hyperglycemia state; Mg, magnesium; PVD, peripheral vascular disease.

In addition, the advent of CGM and automated insulin delivery (AID) systems has resulted in a new risk-benefit paradigm. These technologies enable improvements in TIR (and HbA1c) while mitigating hypoglycemia and hyperglycemia risk.^{12 -14},^{24 -27}

The current consensus recommendations do not reflect the high clinical, functional, and cognitive heterogeneity observed in the older population. In addition to age, clinical, biological and functional status will impact a person’s life expectancy and their ability to care for their diabetes. The ADA has developed a goal framework for HbA1c and fasting, and preprandial glucose level based on health status in older adults to reflect such heterogeneity. ⁹ In this article, we propose a similar approach for CGM metrics and suggest that there is a need to update consensus CGM targets for older adults to better align with current data and to account for health status in addition to age alone.

Heterogeneity of Older Population: Chronological, Biological, Functional, and Cognitive Status

Commonly, the definition of “old” is based on chronological age; however, at each chronological age, people may be at very different biological ages. ²⁸ In fact, aging is a heterogeneous and multifactorial process that includes biological, functional, clinical, and socio-psychosocial changes that occur differently for each person. Older adults with diabetes may have an even greater degree of heterogeneity as the condition, with its varying age of onset, glucose control, and genetic predisposition, may impact biological aging differently (Figure 2).

Figure 2.

Periodic assessment of biological, functional, and clinical function in older adults to assess health status and consider changes in CGM glucose target.

Abbreviation: CGM, continuous glucose monitoring.

The number of older adults living with diabetes has increased due to a longer overall lifespan and improvements in the management of diabetes and diabetes-related complications.^2,29 In the United States, the chronological definition of “old” is an age of 65 years or greater. This cutoff is used as the eligibility criteria to apply for federal health insurance, Medicare. ³⁰ In 2021, the global prevalence of older adults with T2D ≥ 65 was >15% worldwide. ² In the United States, >37 million persons have diabetes, which represents ~11% of the US population. ³¹ However, older adults with diabetes represent ~29% of the overall US population with diabetes. ¹ In the general population, the prevalence of diabetes type, based on self-reported data in older adults is roughly 0.55% for T1D and 8.6% for T2D.^1,32

Older adults represent a unique cohort of individuals. Many, especially those with T1D who have lived with this complex condition for several decades, may have developed chronic diabetes-related complications including IAH. These chronic complications may be superimposed upon changes in socioeconomic status, living status, and accelerated dependence upon others in activities of daily living. All these potential changes, along with variable grade of complications, may adversely impact the ability of older adults to attending to diabetes self-care, and lead to an increased risk for severe hypoglycemia (SH) ³³ and its poor consequences.^34,35 (Figure 2). Altogether, chronological, biological, and psychosocial changes impact each person’s health status differently, making the older population with diabetes a very heterogeneous group who require individualized goals and approaches for their diabetes management.

Biological aging is related to cellular senescence, which is modulated by genetic and epigenetic factors. ³⁶ Biologic aging is highly variable among individuals and, in people with diabetes, this process is accelerated. Specifically, hyperglycemia accelerates the aging process, due to increased oxidative stress, Advanced Glycation End Product (AGE) formation and inflammation, ³⁷ including contributing to dementia, peripheral and autonomic neuropathy, and IAH. ³⁸

The longer we live, the greater our life expectancy is, a form of survivor bias. In fact, data suggest that a 65-year-old person with diabetes and an HbA1c of 8.0% (64 mmol/mol) may have a greater total lifespan than a 50-year-old person with the same HbA1c. ³⁹ Glucose control is impacted by aging and is important at all ages for its effects on both acute and chronic health outcomes, which are summarized in Table 1.

Due to the dynamic processes of aging, physical and cognitive functions may decline independently of one another and are influenced by a background of comorbidities, including diabetes-related complications, which may vary in their type and severity (Figure 2). Older people with diabetes may have considerable functional impairment and impaired health compared with age-matched individuals without diabetes.^35,40

Moreover, frailty, a geriatric syndrome characterized by a decline in physical reserves resulting in high vulnerability to minor stress and reduced ability to maintain physiological homeostasis, occurs earlier and is more prevalent in people with diabetes. ⁴⁰ An estimated 25% of older adults with diabetes are frail. ⁴⁰ Frailty in diabetes is associated with an increased risk of complications, hospitalization, and functional decline and mortality. ⁴¹ Conversely, observational studies in older adults with diabetes and frailty suggest that the degree of glycemia has little to no effect on functional status in the short-term, as long as there is no prolonged severe hyperglycemia. ⁴² Hence, avoidance of both marked and prolonged hyperglycemia and hypoglycemia should be a priority.

Cognitive dysfunction is more frequent in older adults with diabetes. ³⁴ Both elevated HbA1c levels and SH are associated with a higher risk of dementia, which in turn will negatively impact the older adult’s ability to manage their diabetes. ⁴³ The presence of cognitive dysfunction either independently or in the presence of physical impairment (ie, frailty, vision or hearing loss, impaired balance, and reduced dexterity) ⁴⁴ may influence an individual’s ability and the time needed to perform diabetes-related self-care tasks, in particular timely prevention and/or treatment of hypoglycemia.

Therefore, clinicians should periodically evaluate an older adult’s cognitive and functional status along with any deterioration in glycemic control, including hypoglycemia risk, and reassess their therapeutic management and glycemic goals.

Use of CGM and Outcome Data in Older Adults

Information on CGM use by older adults is still relatively limited. The early clinical trials of diabetes-related technologies enrolled relatively few older adults, limiting the available information on the benefits and challenges of such devices in this population.^{45 -48} More recent studies have prioritized enrolling older adults (defined as those aged ≥60 years ¹³ ) but have included few adults aged ≥70 years. Only one study has characterized their health status in detail. ⁴⁹ In those studies, where the relevant documentation is available, those recruited were cognitively intact and non-frail. Nevertheless, glucose outcomes following the use of CGM and AID systems by healthy older participants were at least equal to those obtained in younger cohorts.^26,27

The first study assessing the benefit of CGM use in an older population was a post hoc analysis in older adults (defined as aged ≥60 years; mean age 67 ± 5 years) on multiple daily (insulin) injections (MDI). ¹² Older participants with T1D and T2D on MDI using adjunctive CGM therapy versus self-monitoring of blood glucose (SMBG) improved their HbA1c levels by 0.4%, with a corresponding improvement in TIR; however, TBR was low at baseline and did not significantly decrease. More recently, in the WISDM trial, older adults (defined as aged ≥60 years; mean age 68 years, in the interquartile range [IQR] of 65-71 years) with T1D randomized to using CGM versus SMBG had a significant improvement in their TIR and reduction in hypoglycemia. ¹³ Limited data on their health status were presented, with more than 80% with intact cognitive status and no data on functional status.

Two small studies by McAuley et al ²⁶ and Broughton et al ²⁷ enrolled, respectively, 30 (defined as aged ≥60 years; mean age 67 ± 5 years) and 37 (≥60 years; median [IQR] age 68 [63-70] years) high-functioning older adults with T1D to compare the use of automated insulin delivery (AID) systems with sensor-augmented insulin pumps. These trials showed improvements in TIR, whereas TBR was low at baseline and did not change or only minimally changed.

Real-world data from older adults using CGM ⁵⁰ (longitudinal cohort; mean age 43.3 ± 16.6 years) and AID systems (defined as age ≥65 years; mean age 70 ± 4 years) ²⁴ have generally reflected clinical trial data and indicate that older adults with T1D enrolled in randomized controlled trials do at least as well, if not better than the general T1D population, with technology suggesting that chronological age alone should not preclude the use of advanced diabetes technologies.

Two main CGM outcome metric clusters have been reported in the general T1D population, with TAR, mean glucose, and TIR forming one cluster and with glucose CV and TBR making up the second cluster. ⁵¹ Evidence suggests that these relationships are preserved in older adults. For example, in a large cohort of 165 older adults with T1D (mean age 70 years) TBR was 3.3%. When older adults were stratified by CV (cutoff of 36%), older adults with CV ≤36% spent significantly less TBR <70 mg/dL (<3.9 mmol/L) and TBR <54 mg/dL (<3.0 mmol/L) although they had similar mean HbA1c levels (7.3% or 56 mmol/mol) ²⁰ (Figure 1, panel A). Moreover, a longitudinal analysis following an AID intervention in a cohort with T1D, which included an older subgroup (defined as age ≥60 years), revealed that post-intervention changes in CV were strongly correlated with changes in TBR and that changes in TAR strongly correlated inversely with changes in TIR. Conversely, changes in TIR were only very weakly related to changes in TBR and CV. ⁵²

However, in 2022, the T1D Registry data from the United States ⁵³ showed lower CGM use after the age of 60 years. Factors responsible for this decline were not available; however, one can hypothesize that these factors may have included diminished capacity to use these devices, financial and insurance limitations, and prejudice on the part of prescribers. Insights may be gained from a real-world study of initiation of AID in older adults where physical and cognitive impairment were reported among barriers to initiate or use advanced diabetes-related technologies. ²⁴ Therefore, periodic assessment of functional and cognitive status, their impact on ability to use diabetes-related devices, and the need for educational support and/or caregiver involvement is needed.

Overall, these findings suggest that CGM and AID systems improve TIR while reducing TBR, along with reductions in glycemic excursions. Moreover, TIR and TBR correlate weakly. Therefore, the consensus recommendation of lower TIR to achieve less hypoglycemia may not be justified in those individuals using CGM or AID systems (Figure 1).

A Critical Review of Current Consensus CGM Targets in Older Adults

In the pre-CGM/AID era, a progressive reduction in hyperglycemia exposure, as reflected by HbA1c, was associated with an increasing risk of SH. ⁵⁴ The current consensus CGM guideline for older adults reflects this approach. ¹⁵ In light of the poor health consequences of SH, which can be catastrophic and life-threatening, the authors of the consensus have prioritized hypoglycemia avoidance. To achieve this aim, they propose reductions in TIR targets as a compromise to facilitate attaining stricter hypoglycemia targets. ¹⁵ However, the ability of many older adults to address an impending hypoglycemic episode may be significantly slower than the general population and therefore a hypoglycemia buffer zone prior to the TBR cutoff at 70 mg/dL may be useful (Figure 3).

Figure 3.

Current and proposed CGM-based glycemic goals in older adults with diabetes, based on health status.

Abbreviations: CGM, continuous glucose monitoring; TAR, time above range; TBR, time below range; TIR, time in range.

We therefore suggest a revision of the consensus CGM targets for older adults to better align with current available data. Specifically, we suggest that the definition of TBR for older adults be divided into three categories based on the health status: healthy, intermediate, and poor health (Table 2) in keeping with the ADA approach. ⁹ We have modified the definitions for TBR, TIR, and TAR ranges and the percent time in each of these ranges that one should aim for (Table 2, Figure 3). Specifically, given the very weak relationship between TIR and TBR, we suggest that, for those using CGM or AID systems, minimization of hypoglycemia should not be linked with sacrifices in TIR as the main outcome of such a strategy will be increased hyperglycemia and likely higher glucose variability, which will have its own adverse impact, with little benefit on hypoglycemia risk. Rather, a slight relaxation of TIR targets is better linked with reduced burden on the person with diabetes and their family in achieving these defined goals of care (Figure 3).

Table 2.

Suggested Recommendation Based on Health Status for Glycemic Goals, Rationale, and Strategies to Achieve Goals.

Health status	Proposed glycemic goals	Rationale/considerations	Strategies to achieve glycemic control
Healthy Comorbidities do not interfere with self-care Intact cognition No caregiver need	TBR <70 mg/dL 0% Hypoglycemia buffer zone 70-90 mg/dL <4% TIR 90-180 mg/dL >70% TAR 180-250 <25% TAR>250 <10% CV <33%	Individuals can generally perform complex tasks to maintain good glycemia and use current diabetes-related technologies management when health is stable. During acute illness, individuals may be more at risk for administration or dosing errors that can cause, for example, hypoglycemia, falls, and fractures. Consider to use temporary target for skilled nursing facility	Alert for Low increase to 80 mg/dL to provide time to treat for impending hypoglycemia High alert turn off to reduce anxiety (or increase to >200 mg/dL) to avoid extra-correction and/or stacking insulin, potentially resulting in hypoglycemia and increased glycemic variability
Intermediate >5 comorbidities Mild to moderate cognitive impairment Two or more instrumental ADL impairments	TBR <70 mg/dL 0% Hypoglycemia Buffer Zone 70-100 mg/dL <4% TIR 100-200 mg/dL >70% TAR >200 mg/dL <25% TAR >200 mg/dL <10%	Comorbidities may affect self-management and capacity to avoid hypoglycemia Individuals may be more at risk for dosing errors that can result in hypoglycemia, falls, or fractures. Hypoglycemia and severe hypoglycemia may result in poor outcomes. Mild hyperglycemia can be tolerated	Consider caregiver support Simplify insulin regimen with fixed doses and fixed corrections to avoid reactive treatment Relax glycemic goal Relax Alert and Alarm Discuss change in glycemic goals to mitigate hypoglycemia and hypoglycemia–related goal Alert for Low increase to 90 mg/dL to provide time to treat for impeding hypoglycemia High alert turn off to reduce anxiety (or increase to >250 mg/dL) to avoid extra-correction and/or stacking insulin, potentially resulting in hypoglycemia and increase in glycemic variability Consider to have care giver attend education visit to learn to manage diabetes
Poor health End-stage chronic disease Moderate-to-severe cognitive dysfunction 2+ ADL dependency	TBR <70 mg/dL 0% Hypoglycemia buffer zone 70-100 mg/dL <4% TIR 100-250 mg/dL >70% TAR >250 mg/dL <25%	No hypoglycemia (TBR <70 0%) TIR goal 100-250 CV< avoid wide fluctuation high follows low and vice versa	Need care giver support Alert for Low on 100 mg/dL High alert turn off to reduce anxiety

Abbreviations: ADL, activities of daily living; CV, coefficient of variation; TAR, time above range; TBR, time below range; TIR, time in range.

In Table 2, the definitions for health status are summarized along with the proposed new glycemic goals, the rationale and considerations for such suggestions, and potential strategies to achieve glycemic control.

For all categories of health, we propose that the older adult avoids any CGM reading of <70 mg/dL (<3.9 mmol/L) and to add a hypoglycemia buffer zone between TIR and TBR that can be used by older adults to swiftly and mindfully treat impending hypoglycemia while avoiding both hypoglycemia and/or rebound hyperglycemia. This adjustment will help ensure that TIR is optimized while minimizing glycemic variability as measured by CV, which will result in avoidance of extremes in both hypoglycemia and hyperglycemia events. In addition, it is recommended that clinicians assess and discuss strategies for the treatment of and prevention of hypoglycemia in the older patient at each clinical visit even if their CGM tracing does not reveal any hypoglycemia (Table 2). The goal in this age group is not only avoidance of CGM-detected hypoglycemia but also the need to prevent hypoglycemia.

Therefore, we suggest a change in the definition of the targeted glucose range for the older adult. We advocate for complete avoidance of any CGM readings <70 mg/dL (<3.9 mmol/L) and we propose a hypoglycemia buffer zone for the healthy older adult, ranging between 70 and 90 mg/dL (3.9-5 mmol/L) and, for the older adult with intermediate or poor health status, a hypoglycemia buffer zone ranging between 70 and 100 mg/dL (3.9-5.6 mmol/L). We propose the goal of time spent in this hypoglycemia buffer zone to be <4%. These modifications will help to avoid clinically significant hypoglycemia in those older adults who are most vulnerable and will allow—using the hypoglycemia buffer zone—sufficient time for the older adult and/or their caregiver to address impending hypoglycemia and reduce the risk of SH and/or rebound hyperglycemia due to overtreatment in the presence of symptoms.

In older adults with intermediate and poor health, we suggest an increase in the glucose value for the upper limit for TIR from 180 mg/dL (10 mmol/L) to 200 mg/dL (11.1 mmol/L) and 250 mg/dL (13.9 mmol/L), respectively. Relaxing the upper limit of the CGM TIR along with de-intensification and/or simplification of diabetes-management may reduce the burden of diabetes treatment placed upon the patient and/or their caregiver (Figure 3).

In addition, given the adverse impact of the extreme high-glucose levels, we propose a change in the target duration of the time spent in the aforementioned new upper limits. For healthy older adults, we propose changing the goal for the time spent above 180 mg/dL (10 mmol/L) to <25% and for the time spent above 250 mg/dL (13.9 mmol/L) to <10%, while changing the goal for those with intermediate health to <25% of time above 200 mg/dL (11.1 mmol/L) and retaining a target of <10% above 250 mg/dL (13.9 mmol/L). Those individuals with poor health need to have a goal of <25% of time above 250 mg/dL (13.9 mmol/L). In the near future, with further improvement of AID, it is likely that the time spent in hyperglycemia can be further reduced without increasing risk of hypoglycemia.

Finally, given that the extremes of glycemia are related to the greatest adverse effects, in older adults, consideration should be given to incorporating a composite metric that weights these extremes. The Glycemic Risk Index (GRI) would be an appropriate candidate. ⁵⁵ The GRI is a novel composite metric assessing overall glycemic risk, accounting for both hypoglycemia and hyperglycemia, and is weighted toward extremes. In a recent study, GRI strongly correlated with TIR (r = −0.974), CV, r = 0.683, and time spent in hypoglycemia. ⁵⁶ Therefore, the use of GRI may better reflect the changes in TBR and TAB compared with TIR alone that is important to describe CGM metrics and the risk for hypoglycemia and hyperglycemia. This may be particularly relevant in vulnerable subgroups, such as the older population. ⁵⁷

We await clinical outcome data pertaining to this novel CGM metric in older adults.

Conclusions and Future Directions

There has been major progress in the development and clinical use of diabetes technology, such as CGM and AID systems, for people living with diabetes. Some studies and clinical guidelines specifically address the care of older adults with diabetes, and this body of research will be increasingly relevant as the number and proportion of middle-aged and older people with diabetes increases. We expect that, as CGM and AID technologies evolve, these devices will be of growing importance as therapeutic options for older adults with diabetes. The need for therapeutic targets reflecting patient-centered care is essential in implementing these life-changing technologies and our proposed CGM targets reflect this approach.