Table 2.
Comparison of the demographic and clinical characteristics and the clinical impacts of diabetic peripheral neuropathy on pain, sleep, and quality of life in three clustered groups in already diagnosed patients (n = 1073).
| Variable | Cluster 1 (n = 542) |
Cluster 2 (n = 407) |
Cluster 3 (n = 124) |
P value |
|---|---|---|---|---|
| Age, years | 61.2 ± 10.7 | 62.7 ± 10.9 | 60.3 ± 11.2 | 0.030 |
| Female, n (%) | 267 (49.3) | 245 (60.2) | 79 (63.7) | <0.001 |
| Diabetes treatment, n (%) | <0.001 | |||
| Diet and exercise | 12 (2.2) | 4 (1.0) | 0 (0.0) | |
| OHA | 347 (64.0) | 203 (49.9) | 49 (39.5) | |
| Insulin | 54 (10.0) | 67 (16.5) | 26 (21.0) | |
| Insulin and OHA | 129 (23.8) | 133 (32.7) | 49 (39.5) | |
| BMI, kg/m2 | 24.8 ± 3.4 | 25.0 ± 3.7 | 25.5 ± 3.8 | 0.165 |
| FPG, mg/dL | 141.6 ± 49.8 | 141.7 ± 52.0 | 164.2 ± 89.6 | 0.001 |
| HbA1c, % | 7.6 ± 1.5 | 7.7 ± 1.5 | 8.3 ± 2.1 | <0.001 |
| HbA1c, mmol/mol | 60.0 ± 16.6 | 60.5 ± 16.4 | 67.0 ± 22.5 | <0.001 |
| Hypertension | 339 (62.6) | 277 (68.1) | 87 (70.2) | 0.107 |
| Dyslipidemia | 294 (54.2) | 217 (53.3) | 61 (49.2) | 0.596 |
| Obesity | 42 (7.8) | 19 (4.7) | 12 (9.7) | 0.070 |
| Diabetic retinopathy, n (%) | 162 (29.9) | 155 (38.1) | 55 (44.4) | 0.002 |
| Diabetic nephropathy | 109 (20.1) | 112 (27.5) | 33 (26.6) | 0.021 |
| MNSI score | 1.8 ± 1.6 | 3.6 ± 1.9 | 5.8 ± 2.4 | <0.001 |
| Pain severity items | ||||
| Worst | 0.6 ± 1.4 | 4.9 ± 2.8 | 7.8 ± 1.9 | <0.001 |
| Weakest | 0.1 ± 0.3 | 1.2 ± 1.6 | 2.8 ± 2.1 | <0.001 |
| Average | 0.3 ± 0.7 | 2.8 ± 1.9 | 5.4 ± 1.8 | <0.001 |
| Pain interference items∗ | ||||
| General activity | 0.2 ± 0.7 | 2.2 ± 2.8 | 6.2 ± 2.8 | <0.001 |
| Mood | 0.3 ± 1.1 | 3.0 ± 3.0 | 7.0 ± 2.2 | <0.001 |
| Walking | 0.1 ± 0.7 | 2.1 ± 2.9 | 5.7 ± 3.1 | <0.001 |
| Normal work | 0.1 ± 0.7 | 2.0 ± 2.8 | 6.0 ± 3.0 | <0.001 |
| Relationship | 0.1 ± 0.5 | 1.0 ± 2.1 | 4.2 ± 3.4 | <0.001 |
| Sleep | 0.2 ± 0.9 | 2.2 ± 3.0 | 5.9 ± 3.3 | <0.001 |
| Enjoyment of life | 0.1 ± 0.6 | 1.7 ± 2.6 | 5.4 ± 3.3 | <0.001 |
| Pain interference index | 0.9 ± 2.3 | 10.4 ± 6.5 | 20.4 ± 6.2 | <0.001 |
| MOS-SS† | ||||
| Sleep quantity | 4.8 ± 1.5 | 3.7 ± 1.8 | 2.5 ± 1.5 | <0.001 |
| Respiratory problem during sleep | 5.9 ± 0.4 | 5.7 ± 0.8 | 5.0 ± 1.5 | <0.001 |
| Sleep initiation problem | 5.2 ± 1.4 | 4.1 ± 1.9 | 3.1 ± 1.8 | <0.001 |
| Sleep maintenance problem | 5.1 ± 1.4 | 4.1 ± 1.8 | 3.3 ± 1.8 | <0.001 |
| Somnolence | 5.7 ± 0.8 | 5.1 ± 1.3 | 4.5 ± 1.5 | <0.001 |
| Sleep adequacy | 5.0 ± 1.4 | 4.0 ± 1.8 | 3.0 ± 1.8 | <0.001 |
| Sleep problem index | 31.7 ± 4.6 | 26.6 ± 6.2 | 21.4 ± 6.2 | <0.001 |
| EQ-5D§ | ||||
| Mobility | 1.1 ± 0.3 | 1.4 ± 0.5 | 1.9 ± 0.5 | <0.001 |
| Self-care | 1.0 ± 0.1 | 1.1 ± 0.4 | 1.4 ± 0.5 | <0.001 |
| Usual activity | 1.0 ± 0.2 | 1.3 ± 0.5 | 2.0 ± 0.5 | <0.001 |
| Pain discomfort | 1.1 ± 0.3 | 1.7 ± 0.5 | 2.4 ± 0.5 | <0.001 |
| Anxiety/depression | 1.2 ± 0.4 | 1.4 ± 0.6 | 2.1 ± 0.7 | <0.001 |
| EQ-5D index§ | 5.4 ± 0.8 | 7.0 ± 1.5 | 9.7 ± 1.5 | <0.001 |
| EQ-5D VAS‡ | 77.9 ± 12.8 | 64.0 ± 16.1 | 44.2 ± 19.0 | <0.001 |
| Medications for DPN | ||||
| None | 142 (26.2) | 79 (19.4) | 21 (16.9) | 0.013 |
| Antidepressants | 50 (9.2) | 60 (14.7) | 17 (13.7) | 0.027 |
| Anticonvulsants | 67 (12.4) | 99 (24.3) | 31 (25.0) | <0.001 |
| α-Lipoic acid | 148 (27.3) | 91 (22.4) | 27 (21.8) | 0.154 |
| γ-Linoleic acid | 47 (8.7) | 29 (7.1) | 14 (11.3) | 0.323 |
| Others | 113 (20.9) | 80 (19.7) | 26 (21.0) | 0.891 |
Data are expressed as means ± SD for continuous variables and frequency (%) for categorical variables. ∗Items were derived from the BPI-SF. A 0–10 numeric rating scale was anchored at 0 for “no pain” and 10 for “pain as bad as you can imagine.” †Item response on a 6-point scale ranging from 1 for “all of the time” to 6 for “none of the time;” dimensions of sleep quantity, “get the amount of sleep you needed;” and sleep adequacy, “get enough sleep to feel rested upon waking in the morning” were calculated backwards. §Items were from three levels indicating “no problem” (or 1), “some problems” (or 2), and “severe problems” (or 3), and EQ-5D index was the sum of scores of 5 dimensions. ‡Values from 0 to 100, where 0 represents the worst imaginable health state and 100 represents the best imaginable health state. OHA: oral hypoglycemic agent(s); BMI: body mass index; FPG: fasting plasma glucose; MNSI: Michigan Neuropathy Screening Instrument questionnaire; MOS-SS: medical outcomes study sleep scale; EQ-5D: EuroQol, 5-dimensions; VAS: visual analog scale.