Fasting glucose level is associated with nocturnal hypoglycemia in elderly male patients with type 2 diabetes

Figures & data

Table 1. Clinical characteristics and therapeutic strategy of study subjects (mean±SD).

Variables	With nocturnal hypoglycemia (n = 124)	Without nocturnal hypoglycemia (n = 167)	p
Age (year)	75.7 ± 9.1	76.7 ± 9.1	0.365
BMI (kg/m^2)	25.2 ± 2.6	25.1 ± 2.7	0.843
WC (cm)	95.9 ± 8.6	94.4 ± 9.0	0.178
Diabetes duration (year)	16.7 ± 9.6	16.2 ± 9.7	0.629
SBP (mmHg)	128.4 ± 12.3	127.6 ± 11.6	0.598
DBP (mmHg)	72.1 ± 8.7	71.9 ± 8.0	0.860
HbA1c (%)	7.02 ± 1.09	7.21 ± 1.31	0.206
FPG (mmol/L)	5.88 ± 1.92	6.30 ± 1.59	0.046
2h-PPG (mmol/L)	9.32 ± 2.83	9.45 ± 2.81	0.702
TC (mmol/L)	4.11 ± 0.86	4.20 ± 0.81	0.380
TG (mmol/L)	1.38 ± 0.70	1.46 ± 0.97	0.426
LDL-c (mmol/L)	2.38 ± 0.72	2.40 ± 0.66	0.739
HDL-c (mmol/L)	1.13 ± 0.27	1.14 ± 0.36	0.787

BMI, body mass index; WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, glycated hemoglobin; FPG, fasting plasma glucose; 2h-PPG, 2h plasma glucose; TC, total cholesterol; TG, triglyceride; LDL-c, LDL cholesterol; HDL-c, HDL cholesterol.

Data are the means ± SD.

Table 2. CGM variables of study subjects (mean ± SD).

Variables	With nocturnal hypoglycemia (n = 124)	Without nocturnal hypoglycemia (n = 167)	p
MBG (mmol/L)	7.11 ± 1.07	7.88 ± 1.45	<0.001
Daytime MBG (mmol/L)	7.79 ± 1.35	8.27 ± 1.62	0.007
Nighttime MBG (mmol/L)	5.94 ± 1.12	7.21 ± 1.42	<0.001
SDBG (mmol/L)	1.90 ± 0.77	1.43 ± 0.66	<0.001
Daytime SDBG (mmol/L)	1.68 ± 0.71	1.36 ± 0.65	<0.001
Nighttime SDBG (mmol/L)	0.92 ± 0.51	0.76 ± 0.48	0.006
Fasting glucose (mmol/L)	5.88 ± 1.29	6.92 ± 1.32	<0.001
Bedtime glucose (mmol/L)	7.33 ± 1.70	8.01 ± 1.95	0.002

MBG, mean blood glucose; SDBG, standard deviation of blood glucose.

Figure 1. Prevalence of nocturnal hypoglycemia categorized by quartiles of fasting glucose (A) or bedtime glucose (B).

Table 3. Association between fasting glucose or bedtime glucose and nocturnal hypoglycemia.

	Unadjusted	Model 1	Model 2	Model 3
Fasting glucose
Quartile 1 (<5.6 mmol/L)	6.55 (3.18–13.5)	6.11 (2.71–13.8)	6.40 (2.73–15.0)	6.41 (2.57–16.0)
Quartile 2 (5.6–6.3 mmol/L)	2.34 (1.12–4.64)	1.65 (0.77–3.57)	1.78 (0.80–3.93)	1.72 (0.72–4.08)
Quartile 3 (6.3–7.3 mmol/L)	1.08 (0.52–2.23)	0.99 (0.45–2.18)	1.11 (0.50–2.50)	1.06 (0.46–2.46)
Quartile 4 (≥7.3 mIU/L)	1.00	1.00	1.00	1.00
p	<0.001	<0.001	<0.001	<0.001
Bedtime glucose
Quartile 1 (<6.4 mmol/L)	2.94 (1.48–5.85)	2.34 (1.05–5.20)	2.93 (1.23–6.94)	2.86 (1.18–6.95)
Quartile 2 (6.4–7.4 mmol/L)	1.37 (0.70–2.71)	1.23 (0.56–2.66)	1.53 (0.67–3.49)	1.61 (0.69–3.74)
Quartile 3 (7.4–8.6 mmol/L)	1.57 (0.80–3.10)	1.43 (0.68–3.02)	1.65 (0.76–3.57)	1.60 (0.72–3.56)
Quartile 4 (≥8.6 mmol/L)	1.00	1.00	1.00	1.00
p	0.018	0.176	0.099	0.138

Data are OR (95%CI). Participants with nocturnal hypoglycemia was defined as 1 and without as 0.

Model 1: Adjusted for age, BMI, waist circumference, and diabetic duration.

Model 2: Further adjusted for insulin, sulfonylureas or glinides therapy based on model 1.

Model 3: Further adjusted for HbA1c, fasting plasma glucose and postprandial plasma glucose based on model 2.

Figure 2. Area under the ROC curve for fasting glucose or bedtime glucose predicting nocturnal hypoglycemia. Using the area under receiver operating characteristic (ROC) curve, fasting glucose but not bedtime glucose, was a predictor of nocturnal hypoglycemia, with an area under the ROC curve (AUC) of 0.714 (95%CI: 0.653 ∼ 0.774, p < 0.001) and 0.604 (95%CI: 0.538∼0.670, p = 0.002).

Table 4. Optimal cutpoint of fasting glucose or bedtime glucose predicting nocturnal hypoglycemia.

	Fasting glucose			Bedtime glucose
Blood glucose (mmol/L)	Sensitivity	Specificity	Youden index	Sensitivity	Specificity	Youden index
5.7	42.7 (53)	83.8 (140)	0.265	15.3 (19)	91.6 (153)	0.069
5.9	52.4 (65)	76.0 (127)	0.284	20.2 (25)	88.6 (148)	0.088
6.1	61.3 (76)	70.7 (118)	0.320	22.6 (28)	86.2 (144)	0.088
6.3	67.7 (84)	63.5 (106)	0.312	30.6 (38)	83.2 (139)	0.138
6.5	72.6 (90)	58.7 (98)	0.313	35.5 (44)	77.2 (129)	0.127
6.7	76.6 (95)	52.1 (87)	0.287	37.9 (47)	72.5 (121)	0.104
6.9	79.0 (98)	47.9 (80)	0.269	46.8 (58)	68.9 (115)	0.157
7.1	83.9 (104)	38.9 (65)	0.228	50.0 (62)	62.3 (104)	0.123
7.3	84.7 (105)	31.1 (52)	0.158	53.2 (66)	56.3 (94)	0.095
7.5	87.1 (108)	25.7 (43)	0.128	57.3 (71)	52.1 (87)	0.094

Data are % (n).