Does Diabetes Double the Risk of Depression?

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Figure 1.
Predicted likelihood of a new depression diagnosis among diabetic patients and nondiabetic patients matched for age and sex (N = 28,288).
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Figure 2.
Predicted likelihood of a new depression diagnosis among diabetic patients and nondiabetic control patients matched for age, sex, and number of primary care visits (N = 27,924).

Table 1.

Characteristics of Patients With Prevalent Diabetes and Matched Nondiabetic Patients

		Nondiabetic Patients Matched for:
Characteristic	Diabetic Patients (n=14,144)	Age and Sex (n=14,144)	Age, Sex, and Visits (n=13,962)
SE=standard error.
^a P <.001 relative to the diabetic patients.
Age, mean (SE), years	61.0 (0.12)	61.0 (0.12)	60.9 (0.12)
Male, %	51.9	51.9	51.7
Number of primary care visits, mean (SE)	6.7 (0.04)	4.5 (0.04)^a	6.4 (0.05)^a
Comorbidity score ≥1, %	15.4	9.9^a	11.6^a
Enrollment ≤19 months, %	24.2	19.5^a	16.6^a
New depression diagnosis, %	7.9	5.5	8.6

Table 2.

Characteristics of Patients With Incident Diabetes and Matched Nondiabetic Patients

		Nondiabetic Patients Matched for:
Characteristic	Diabetic Patients (n=2,932)	Age and Sex (n=2,932)	Age, Sex, and Visits (n=2,921)
SE=standard error.
^a P <.001 relative to the diabetic patients.
Age, mean (SE), years	56.6 (0.28)	56.6 (0.28)	56.6 (0.28)
Male, %	52.7	52.7	52.6
Number of primary care visits, mean (SE)	6.8 (0.11)	3.8 (0.08)^a	6.3 (0.10)^a
Comorbidity score ≥1, %	12.4	7.0^a	8.2^a
Enrollment ≤19 months, %	17.8	23.7^a	17.2
New depression diagnosis, %	9.4	5.7	8.6

Table 3.

Predictors of a New Depression Diagnosis Among Patients With Prevalent Diabetes Relative to Matched Nondiabetic Patients

Parameter	Age-Sex Coefficient^a	PValue	Age-Sex-Visit Coefficient^a	PValue
PC=primary care.
^a A positive coefficient indicates an increased likelihood of a depression diagnosis after the index date; a negative coefficient indicates a decreased likelihood.
^b Age was centered around the mean of 61 years.
^c Number of primary care visits was centered around the median of 6.
Diabetes
Incident	0.577	<.001	0.002	.98
Prevalent	0.543	<.001	−0.083	.08
Age
Linear^b	0.011	<.001	0.004	.01
Quadratic	0.0002	.002	0.0002	.009
Sex (male)	−0.421	<.001	−0.474	<.001
Number of PC visits
Linear^c	−0.087	<.001	−0.088	<.001
Quadratic	0.008	<.001	0.006	<.001
Comorbidity score ≥1	0.522	<.001	0.544	<.001
Enrollment ≤19 months	0.012	.91	−0.365	<.001
Interactions
Incident diabetes * number of PC visits	−0.041	.04	−0.034	.09
Prevalent diabetes * number of PC visits	−0.056	<.001	−0.040	<.001
Incident diabetes * enrollment ≤19 months	−0.054	.80	–	–
Prevalent diabetes * enrollment ≤19 months	−0.372	.004	–	–
Number of PC visits * comorbidity score ≥1	−0.056	<.001	−0.066	<.001
Number of PC visits * enrollment ≤19 months	0.110	<.001	0.105	<.001
Statistics
Intercept	−3.056	–	−2.315	–
Likelihood ratio χ²	673.19	<.001	657.94	<.001
C statistic	0.655	.25	0.645	.18
Hosmer-Lemeshow χ²	10.20	–	11.39	–

Table 4.

Predictors of a New Depression Diagnosis Among Patients With Incident Diabetes and Matched Nondiabetic Patients

Parameter	Age-Sex Coefficient^a	PValue	Age-Sex-Visits Coefficient^a	PValue
PC=primary care.
^a A positive coefficient indicates an increased likelihood of a depression diagnosis after the index date; a negative coefficient indicates a decreased likelihood.
^b Age was centered around the mean of 57 years.
^c Number of primary care visits was centered around the median of 6.
Incident diabetes	0.724	<.001	0.113	.23
Age
Linear^b	0.007	.04	0.002	.59
Quadratic	0.0004	.04	0.00008	.64
Sex (male)	−0.488	<.001	−0.570	<.001
Number of PC visits
Linear^c	−0.119	<.001	−0.119	<.001
Quadratic	0.008	<.001	0.006	<.001
Comorbidity score ≥1	1.061	<.001	0.496	<.001
Enrollment ≤19 months	−0.701	.01	−0.222	.14
Interactions
Incident diabetes * comorbidity score ≥1	−0.723	.01	–	–
Incident diabetes * enrollment ≤19 months	0.628	.03	–	–
Number of PC visits * enrollment ≤19 months	0.094	.004	0.106	<.001
Intercept	−3.032	–	−2.269	–