Out of 424 total sample, 25 (5.9%) subjects with incomplete records (unknown date of DM and CVD diagnosis and diagnosed CVD before the diabetes) were excluded making 94.1% of response rate. Then 399 type 1 and type 2 diabetic patients were retrospectively followed from September 5, 2012, to February 25. 2020.
Socio-demographic and clinical characteristics
The mean age at baseline was 43.93+/-15.87 years, with minimum and maximum ages of 15 and 90 years, respectively. Male patients accounted for 61.4% and urban residents reported in 59.15% of study participants and high proportion of CVD were from urban (65.6%). Majority (70.4%) of subjects had T2DM and SBP >/=140 constituted 36.8% of study participants. High percentage of CVDs were happened in T2DM (82.0%) and SBP >/=140 (77.1%). Further details on the socio-demographic and baseline clinical characteristics of the study sample are shown in Table 1.
Table 1: Socio-demographic and clinical characteristics of study participants, 2020.
Variables
|
Status of Cardiovascular disease
|
Total (n=399)
|
CVD (n=61)
|
No CVD (n=338)
|
Age (mean +/- SD)
|
50.19 +/- 14.59
|
42.79 +/-15.78
|
43.93+/-15.87
|
Sex
|
Male
|
38 (62.3)
|
207 (61.2)
|
245 (61.4)
|
Female
|
23 (37.7)
|
131 (38.8)
|
154 (38.6)
|
Residence
|
Urban
|
40 (65.6)
|
196 (58.0)
|
236 (59.2)
|
Rural
|
21 (34.4)
|
142 (42.0)
|
163 (40.8)
|
Family history of DM
|
No
|
50 (82.0)
|
238 (70.4)
|
288 (72.2)
|
Yes
|
11 (18.0)
|
100 (29.6)
|
111 (27.8)
|
Type of DM
|
T1DM
|
11 (18.0)
|
107 (31.7)
|
118 (29.6)
|
T2DM
|
50 (82.0)
|
231 (68.3)
|
281 (70.4)
|
Type of treatment
|
OHA
|
37 (60.6)
|
176 (52.1)
|
213 (53.4)
|
Insulin
|
12 (19.7)
|
108 (31.9)
|
120 (30.1)
|
Both
|
12 (19.7)
|
54 (16.0)
|
66 (16.5)
|
Acute Complication
|
No
|
31 (50.8)
|
198 (58.6)
|
229 (57.5)
|
Yes
|
30 (49.2)
|
139 (41.1)
|
169 (42.5)
|
BMI (kg/m2)
|
<18.5
|
2 (3.3)
|
24 (7.1)
|
26 (6.5)
|
18.5-24.9
|
12 (19.7)
|
238 (70.4)
|
250 (62.7)
|
>=25
|
47 (77.0)
|
76 (22.5)
|
123 (30.8)
|
DBP
|
<90
|
31 (50.8)
|
240 (71.0)
|
271 (67.9)
|
>/=90
|
30 (49.2)
|
98 (29.0)
|
128 (32.1)
|
SBP
|
<140
|
14 (22.9)
|
238 (70.4)
|
252 (63.2)
|
>/=140
|
47 (77.1)
|
100 (29.6)
|
147 (36.8)
|
*CVD cardiovascular disease, SD standard deviation, DM diabetes mellitus, T1DM type one diabetes, T2DM type two diabetes, OHA oral hypoglycemic agent, BMI body mass index, DBP diastolic blood pressure, SBP systolic blood pressure, Kg/m2 kilogram per meter square.
Comorbidities and laboratory characteristics
Table 2 shows the study baseline laboratory and comorbidities characteristics of study participants. The median (IQR) of baseline FBS and creatinine was 186(99) and 0.86 (0 .52), respectively. Regarding the lipid profile of the study participants: 30.8%, 38.8% and 23.6% of patients had triglyceride >/= 200md/dl, LDL-C >/= 100 md/dl and HDL-C <40 md/dl, respectively. Nearly one fifth (20.3%) and 15.8% of patients had diabetic retinopathy and chronic kidney disease comorbid, respectively.
Table 2: Laboratory and comorbidities characteristics of study participants, 2020.
Variables
|
Status of Cardiovascular disease
|
Total (n=399)
|
CVD (n=61)
|
No CVD (n=338)
|
Baseline FBS, Median (IQR)
|
|
178 (92)
|
242 (115)
|
186 (99)
|
Creatinine, Median (IQR)
|
|
1.1 (1.55)
|
0.81 (0 .39)
|
0.86 (0 .52)
|
Total cholesterol(mg/dL)
|
<200
|
30 (49.2)
|
224 (66.3)
|
254 (64.3)
|
200-239
|
9 (14.7)
|
65 (19.2)
|
74 (18.7)
|
>/=240
|
22 (30.1)
|
45 (13.3)
|
67 (17.0)
|
Triglyceride(md/dL)
|
<150
|
9 (14.8)
|
183 (54.1)
|
192 (48.1)
|
150-199
|
11 (18.0)
|
73 (21.6)
|
84 (21.1)
|
>/=200
|
41 (67.2)
|
82 (24.3)
|
123 (30.8)
|
LDL-C(md/dL)
|
<100
|
24 (39.3)
|
217 (64.2)
|
241 (61.2)
|
>=100
|
37 (60.7)
|
116 (34.3)
|
153 (38.8)
|
HDL-C(md/dL)
|
>/=40
|
33 (54.1)
|
268 (79.3)
|
301 (76.4)
|
<40
|
28 (45.9)
|
65 (19.2)
|
93 (23.6)
|
Chronic kidney disease
|
No
|
27 (44.3)
|
309 (91.4)
|
336 (84.2)
|
Yes
|
34 (55.7)
|
29 (8.6)
|
63 (15.8)
|
Diabetic retinopathy
|
No
|
39(63.9)
|
279(82.5)
|
318 (79.7)
|
Yes
|
22(36.1)
|
59(17.5)
|
81 (20.3)
|
*FBS fasting blood sugar, IQR interquartile range, mg/dL milligram per Deciliter, HDL-C high density lipoprotein cholesterol, LDL-C low density lipoprotein cholesterol
Incidence of cardiovascular disease among diabetic patients
We followed study subjects for a median follow up period of 5.89 years (minimum of .66 and maximum of 7.50 years) after initiation of treatment for a total of 2250.4 PY. The entire cumulative incidence of CVD in this study was 15.29 % (61/399; 95% CI: [12.07, 19.18]). The total incidence density was 2.71; 95%CI: [2.11, 3.48] with 2.82; 95%CI: [2.05, 3.87] and 2.55; 95%CI: [1.69, 3.83] per 100 PY among males and females, respectively (no significant difference, p = 0.876). Among diabetic patients who were free from any type of CVD at the start of study, the cumulative proportion of developing CVD was 0.0452, 0.0862, 0.1394 and 0.2511 at year 2, 4, 6 and at the end of the study, respectively (Fig. 1).
Predictors of CVD among diabetic patients
To evaluate the effect of the number of factors on the risk of patients to develop new-onset CVD we fitted Weibull regression which has the lowest AIC compared to all other model. The tolerance of factors ranged from 0.48 to 0.89 and variance inflation ranged from 1.12 to 2.10, indicating an absence of multicollinearity. Schoenfeld residual to test the proportional hazards assumption was not significant (P-value for each variable ranged from 0.111 to 0.777 with global P-value of 0.535) indicates that PHA was satisfied. As well, the Cox Snell residual plot showed the goodness of fitness of the model was satisfied because the cumulative hazard plot follows 45 degree or a straight line through the origin with slope one (Fig. 2). As shown in Table 3: bivariate Weibull regression (95% CI of CHR) shows significant association of age, type of DM, CKD, DR, DBP, SBP, BMI, HDL, LDL, total cholesterol and triglyceride with risk of CVD. But after adjusting for other variable in multivariable Weibull regression, there are three independent variables (CKD, systolic HTN and triglyceride) that significantly determine the risk of CVD in diabetic patients. The risk of CVD was 2.53 times higher among diabetic patients with CKD as compared to those who has no CKD. The hazard of CVD among DM was 4.30 times higher for patients with systolic HTN as compared to their counter parts. Compared to patients with TG <150 mg/dl, diabetic patients with TG >/200 mg/dl had a 5.10-fold higher risk for the incident CVD.
Table 3: Multivariable Weibull regression for predictors of incident CVD among diabetes mellitus patients, 2020.
Variables
|
Categories
|
CHR [95% CI]
|
AHR [95% CI]
|
P-value
|
Age
|
<45
|
1
|
1
|
|
>/=45
|
2.21[1.27, 3.82]
|
1.30[0.62, 2.74]
|
0.483
|
Type of DM
|
TIDM
|
1
|
1
|
|
TIIDM
|
2.07[1.08, 3.97]
|
0.43[0.17, 1.08]
|
0.072
|
CKD
|
No
|
1
|
1
|
|
Yes
|
8.15[4.91, 13.51]
|
2.53[1.36, 4.72]
|
0.003**
|
DR
|
No
|
1
|
1
|
|
Yes
|
2.19[1.30, 3.69]
|
1.07[0.59, 1.95]
|
0.815
|
DBP
|
<90
|
1
|
1
|
|
>/=90
|
2.31[1.40, 3.82]
|
0.82[0.46, 1.44]
|
0.485
|
SBP
|
<140
|
1
|
1
|
|
>/=140
|
6.77[3.73, 12.30]
|
4.30[2.12, 8.73]
|
<0.001***
|
BMI
|
<18.5
|
1
|
1
|
|
18.5-24.9
|
1.36[0.18, 10.43]
|
1.09[0.14, 8.39]
|
0.937
|
>=25
|
11.27[1.55, 16.6]
|
3.39[0.44, 5.86]
|
0.239
|
HDL
|
>=40
|
1
|
1
|
|
<40
|
2.82[1.71, 4.67]
|
0.69[0.37, 1.27]
|
0.234
|
LDL
|
<100
|
1
|
1
|
|
>=100
|
2.46[1.47, 4.12]
|
0.95[0.53, 1.72]
|
0.869
|
Total cholesterol
|
<200
|
1
|
1
|
|
200-239
|
0.95[0.45, 2.01]
|
1.43[0.19, 1.97]
|
0.063
|
>/=240
|
3.02[1.74, 5.24]
|
1.82[0.44, 1.54]
|
0.539
|
Triglyceride
|
<150
|
1
|
1
|
|
150-199
|
2.83[1.17, 6.83]
|
2.50[0.91, 6.88]
|
0.075
|
>/=200
|
7.96[3.87, 16.38]
|
5.10[2.02, 12.89]
|
0.001***
|