Assessment of Glycemic Control Using Continuous Glucose Monitoring During Hospitalization and After Discharge for Older Adults

The annual incidence of inpatient diabetes has doubled over the past 2 decades, resulting in 7.86 million discharges and 43.1 hospital days among US adults in 2020.1 The prevalence of diabetes increases with age, with national estimates indicating that over 20% of individuals between 65 and 75 years old and more than 40% of those over 80 years are affected.2 Improving glycemic control in older adults has reduced both short- and long-term complications and mortality.3 Reducing hypoglycemia is crucial in older adults, as low blood glucose can lead to injuries, cognitive impairment, and cardiac events.4 Clinical guidelines recommend individualized glycemic management regimens for older adults.

Bedside capillary point-of-care (POC) glucose monitoring remains the standard method for assessing glycemic control in hospitals, but continuous glucose monitoring (CGM) offers a more comprehensive 24-hour glycemic profile.2 Studies conducted in hospitals with insulin-treated patients who have type 2 diabetes (T2D) indicate that CGM is accurate and increases the detection of both hypoglycemia and hyperglycemic events compared with POC testing.5 However, there has been limited research on the use of CGM in older adults during their hospitalization and after discharge.

We conducted a pooled analysis of 2 randomized controlled trials using CGM in insulin-treated patients with T2D admitted to general medicine and surgery wards.6 We compared glycemic control between individuals ≥65 and <65 years during hospitalization and 10 days after hospital discharge. All patients wore blinded Dexcom G6 CGM devices and were treated according to an insulin treatment protocol. The primary aim was to determine the difference in the percentage of time in range (TIR 70-180 mg/dL). Secondary outcomes included differences in hyperglycemia, hypoglycemia events, and glycemic variability (GV).

A total of 141 insulin-treated patients with T2D were analyzed, including 33 individuals ≥65 years (mean age 70 ± 4 years) and 108 individuals <65 years (mean age 52 ± 9 years) (Table 1). Older adults with T2D had lower admission HbA1c and mean daily glucose during hospitalization (P = .007) and after discharge (P = .016) than younger adults. They spent a higher percentage of time in range (TIR 70-180 mg/dL) during hospitalization (P = .009) and postdischarge (P = .02), with no significant differences in time below range (TBR <70 mg/dL) compared with individuals <65 years. In addition, CGM demonstrated a more remarkable ability to detect hypoglycemia <70 and <54 mg/dL than capillary POC glucose testing (P < .01), both during hospitalization and after discharge. Older adults exhibited lower GV during hospitalization, although no significant difference in GV was observed postdischarge.

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Table 1.

Glycemic Control by CGM.

Variable	< 65 years (N = 108)	> 65 years (N = 33)	P-value
HbA1c	9.57 ± 2.49	8.14 ± 1.52	.003
Admission glucose, mg/dL	220.35 ± 124.43	162.52 ± 67.89	.003
BMI, kg/m2	33.71 ± 9.33	37.63 ± 11.73	.14
Duration of DM, years	13.03 ± 9.20	17.43 ± 12.90	.11
During hospitalization
Total insulin (units/kg/day)	0.40 ± 0.25	0.37 ± 0.32	.19
Mean daily sensor glucose, mg/dL	186.57 ± 42.44	162.31 ± 35.92	.007
TIR 70-180 mg/dL, (%)	53.04 ± 26.29	69.05 ± 24.89	.009
TAR >180 mg/dL, (%)	46.03 ± 26.54	29.08 ± 25.37	.005
TAR >250 mg/dL, (%)	17.02 ± 21.48	7.65 ± 11.68	.008
TBR <70mg/dL, (%)	0.94 ± 2.05	1.88 ± 3.14	.37
TBR <54 mg/dL, (%)	0.36 ± 1.10	0.96 ± 1.98	.40
GV by MAGE	65.39 ± 32.04	51.06 ± 26.54	.034
GV by SD	49.14 ± 16.68	42.22 ± 17.09	.05
Post discharge period
Mean daily glucose, mg/dL	196.94 ± 50.99	173.43 ± 31.82	.016
TIR 70-180 mg/dL, (%)	43.62 ± 30.38	57.29 ± 24.33	.020
TAR >180 mg/dL, (%)	52.86 ± 30.66	41.24 ± 24.57	.05
TAR >250 mg/dL, (%)	23.07 ± 25.76	10.46 ± 12.96	.040
TBR <70mg/dL, (%)	3.52 ± 10.22	1.47 ± 2.02	.33
TBR <54 mg/dL, (%)	2.86 ± 10.11	0.64 ± 0.98	.10
GV by MAGE	62.07 ± 35.73	59.10 ± 26.32	.96
GV by SD	50.65 ± 18.36	46.91 ± 17.87	.24

BG, blood glucose; DM, diabetes mellitus; BMI, body mass index; TIR, time in range; TAR, Time above range; TBR, time below range; GV, glycemic variability; MAGE, mean amplitude of glycemic excursion, SD, standard deviation.

In summary, older adults with T2D, compared with younger adults with T2D, have better glycemic control on admission, during hospitalization, and after hospital discharge. Continuous glucose monitoring is superior to POC glucose testing in assessing glycemic control in older adults, with higher detection of hypoglycemic events both during hospitalization and after discharge. Our study adds to the growing body of evidence supporting the superiority of CGM over POC glucose testing in evaluating glycemic control in older adults. Effectively integrating CGM could improve inpatient glycemic control, lower hypoglycemia rates, enhance clinical outcomes, and fill the gaps in the older adult population.