Table 1.
Characteristics and results of the 13 studies included in the meta-analysis
| Study | Design | Number of participants | Age (years) |
n Male (%) |
Criteria for depression |
Assessment of DM2/IGM | Fasting plasma glucose (mmol/L) (SD) | Cases of depression | Methodological issues | |
|---|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) | Range | |||||||||
| US: Palinkas et al., 1991 (29) | Population-based study | NGM: 1,284 (81%) | NGM: 69 (10) | ≥50 | NGM: 584 (46%) | Beck Depression Inventory ≥13 | WHO 1985 (OGTT, FPG) | NGM: 4.8 (0.5) UDD: 5.9 (1.5)PDD: 7.1 (2.6) | NGM: 58 (5%) | Excluded participants: -IGT and no personal diabetes history or current use of diabetes medication (n = 559) -Using insulin (n = 6) - Failed to fast for 12 h or missing glucose results (n = 106) |
| UDD: 209 (13%)PDD: 93 (6%) | UDD: 74 (8)PDD: 72 (9) | UDD: 101 (48%)PDD: 56 (60%) | Self-reported diabetes diagnosis by physician | UDD: 8 (4%)PDD: 10 (11%) | ||||||
| Current use of diabetes medication | ||||||||||
| Finland: Hiltunen et al., 1996 (19) | Population-based study | NGT: 149 (40%) | NGT: M 74; W 75 | 70–92 | NGT: 63 (42%) | Short Zung SDS score ≥28 | WHO 1985 (OGTT) | NA | NGT: 26 (17%) | Small sample |
| IGT: 122 (33%)UDD: 33 (9%)PDD: 65 (18%) | IGT: M 76; W 76UDD: M 74; W 78PDD: M 73; W 79(Median) | IGT: 43 (35%)UDD: 12 (36%)PDD: 19 (29%) | Previous diabetes diagnosisReceiving oral drug, insulin, or diet treatment | IGT: 19 (15%)UDD: 6 (18%)PDD: 9 (14%)a | ||||||
| Finland: Rajala et al., 1997 (18) | Population-based study | NGM: 480 (65%)IGT: 192 (26%)UDD: 26 (4%)PDD: 36 (5%) | NGM: 55IGT: 55UDD: 55PDD: 55 | 55 | NGM: 199 (41%)IGT: 85 (44%)UDD: 13 (50%)PDD: 24 (67%) | Zung SDS score ≥45 | WHO 1985 (OGTT)Self-reported diabetes diagnosis by physicianIn patients with random blood glucose value ≥8 2× FG or two FG values ≥6.7 mmol/L | NA | NGM: 56 (12%)IGT: 24 (13%)UDD: 3 (12%)PDD: 9 (25%) | Small samplePDD treatment: diet only, 22 (54%); oral agents, 11 (27%); oral agents and insulin, three (7%); insulin, five (12%)Median diabetes duration 5 years (range 1–40) |
| U.S.: Yaffe et al., 2004 (20) | Intervention multisite (n = 180) multicountry (n = 25) study | NGM: 6,463 (92%)IFG: 297 (4%)PDD: 267 (4%) | NGM: 66 (7)IFG: 68 (7)PDD: 68 (6) | NA | 0 (0%) | 15-item Geriatric Depression Scale ≥6 | FG Self-reported preexisting diabetesCurrently using hypoglycemic medication | NGM: 5.0 (0.4)IFG: 6.4 (0.2)PDD: 8.5 (2.7) | NGM: 142 (2%)IFG: 10 (3%)PDD: 11 (4%)b | Postmenopausal women only Of 267 women with diabetes, 184 (69%) reported having diabetes by history, 198 (74%) had FG level ≥7 mmol/L, and 111 (42%) reported using hypoglycemic medication |
| The Netherlands: Knol et al., 2007 (21) | Population-based study | NFG: 3,499 (81%)IFG: 671 (16%)UDD: 55 (1%)PDD: 102 (2%)c | NGM: 38 (11)IFG: 47 (14)UDD: 57 (13)PDD: 56 (14)c | ≥18 | NGG: 1,414 (40%)IFG: 427 (64%)UDD: 24 (44%)PDD: 54 (53%)c | Symptom Checklist-90depression subscale ≥25 and/or self-reported antidepressant use CES-D ≥16 and/or self-reported use of antidepressant medication | ADA 2005 (FPG)Self-reported diabetes diagnosis by physician | NFG: 4.9 (0.4)IFG: 5.9 (0.3)UDD: 8.3 (2.1)PDD: 8.3 (3.3)c | NFG: 667 (19%)IFG: 115 (18%)UDD: 11 (20%)PDD: 30 (30%)c | Patients with diagnosed diabetes who used insulin and no oral hypoglycemic agents were defined as having type 1 diabetes and were excluded (n = 14) |
| U.S.: Golden et al., 2007 (22) | Population-based study | NGM: 3,911 (58%)IFG: 1,879 (28%)UDD: 292 (4%)PDD: 672 (10%) | Depressed: 61 (10)Nondepressed: 62 (10) | 45–84 | 3,186 (47%) | CES-D ≥16 and/or self-reported use of antidepressant medication | ADA 2003 (FG)Use of hypoglycemic medication (oral agents and/or insulin) | NGM: 5.0 (0.3)IFG: 5.9 (0.3)UDD: 9.0 (3.0)PDD: 8.5 (3.1)d,e | NGM: 721 (18%)IFG: 304 (16%)UDD: 46 (16%)PDD: 153 (23%) | UDD defined as “untreated diabetes”PDD defined as “treated diabetes”Among 292 individuals with untreated diabetes, 50 (17%) were aware of diagnosis. CES-D scores of two groups were not significantly different (P = 0.28) |
| Germany: Icks et al., 2008 (30) | Population-based study | NGM: 3,995 (87%)UDD: 248 (5%)PDD: 352 (8%) | NGM: M: 59 (8) W: 59 (8)UDD: M: 60 (7) W: 62 (8)PDD: M: 63 (7) W: 64 (7) | 45–75 | NGM: 1,905 (48%)UDD: 175 (71%)PDD: 214 (61%) | CES-D short form ≥15 | FG, random blood glucoseSelf-reported diabetes diagnosis by physicianTaking glucose-lowering medication | NGM: 5.8 (0.5)UDD: 8.0 (1.9)PDD: 8.8 (2.5)e | NGM: 557 (14%)UDD: 15 (6%)PDD: 47 (13%) | |
| U.S.: Rhee et al., 2008 (24) | Adult volunteer subjects who were not known to have diabetes | NGT: 642 (61%)Pre-PDD: 352 (34%)UDD: 53 (5%) | NGT: 46 (12)Pre-PDD: 52 (10)UDD: 55 (10) | NA | NGT: 186 (29%)Pre-PDD: 180 (51%)UDD: 24 (45%) | Patient Health Questionnaire-9 ≥10 | ADA 2007 (OGTT, FPG) | NGT: 4.9 (0.4)Pre-PDD: 5.7 (0.1)UDD: 6.9 (0.9)d,e | NGT: 45 (7%)Pre-PDD: 25 (7%)UDD: 6 (11%) | Pre-PDD: IFG and/or IGTEthnicity (% black): NGT 55%; pre-PDD 51%; UDD 62%Past/current depression treatment: NGT: 11/10% Pre-PDD: 11/10% UDD: 4/13% |
| The Netherlands: Adriaanse et al., 2008 (23) | Population-based study | NGM: 260 (47%)IGM: 164 (30%)PDD: 126 (23%) | NGM: 69 (6)IGM: 70 (6)PDD: 71 (7) | 60–87 | NGM: 130 (50%)IGM: 86 (52%)PDD: 60 (48%) | CES-D ≥16 | WHO 1999 (OGTT, FPG) | NGM: 5.4 (0.4)IGM: 6.1 (0.5)PDD: 7.9 (2.1)e | NGM: 20 (8%)IGM: 24 (15%)PDD: 22 (17%) | IGM: IGT or IFG |
| U.K.: Holt et al., 2009 (25) | Population-based study | NGM: 1,568 (52%)IFG: 298 (10%)IGT: 698 (23%)UDD: 249 (8%)PDD: 182 (6%) | Total: 66 M: 66 (3)W: 67 (3) | 59–73 | NGM: 830 (53%)IFG: 207 (69%)IGT: 309 (44%)UDD: 124 (50%)PDD: 108 (59%) | Hospital Anxiety and Depression Scale depression subscale ≥11: probable depression | WHO (year not specified) (OGTT, FPG)Self-reported previous diabetes diagnosis | NGM: NAIGT: 5.9 (1.1)UDD: 7.2 (1.2)ePDD: NA | NGM: 19 (1%)IGT/IGF: 8 (1%)UDD: 6 (2%)PDD: 4 (2%) | Exact number of participants with NGM is unknown |
| U.K.: Aujla et al., 2009 (26) | Population-based study | NGT: 4,956 (82%)IGR: 855 (14%)UDD: 198 (3%) | 58 (10) | 40–75 | 2,849 (47%) | WHO-5 ≤13 | WHO 2006 (OGTT, FG) | NGT: 5.0 (0.4)IGR: 5.7 (0.7)UDD: 8.1 (3.0)e | NGT: 1,035 (25%)IGR: 167 (26%)UDD: 29 (21%) | IGR: IFG and/or IGTWHO-5 is not a measure of depression2% of participants had preexisting history of depressionOverall sample: 4,682 (78%) white European; 1,327 (22%) South Asian |
| U.S.: Gale et al., 2010 (27) | Ex-military personnel randomly drawn from records of U.S. veterans | NFG: 3,573 (83%)IFG: 492 (11%)UDD: 182 (4%)PDD: 46 (1%) | NFG: 38 (3)IFG: 39 (2)UDD: 39 (2)PDD: 40 (2) | 4,293 (100%) | Diagnostic Interview Schedule major depression | Fasting serum glucoseSelf-reported diabetes diagnosis by physicianUse of diabetes medication | NFG: 5.0 (0.3)IFG: 5.8 (0.1)UDD: 7.0 (2.2)PDD: 9.4 (4.3)e,f | NFG: 227 (6%)IFG: 25 (5%)UDD: 16 (9%)PDD: 8 (17%) | Random sample of 15,288 veterans of telephone surveyDiagnosis of depressionRelatively young sampleUDD | |
| The Netherlands: Bouwman et al., 2010 (28) | Population-based study | NGM: 2,061 (77%)IGM: 425 (16%)PDD: 181 (7%) | NGM: 53 (7)IGM: 55 (6)PDD: 56 (6) | 40–65 | NGM: 923 (45%)IGM: 241 (57%)PDD: 97 (54%) | CES-D ≥16 | WHO 2006 (OGTT, FPG) | NGM: 5.3 (0.4)IGM: 6.0 (0.5)PDD: 7.8 (2.2) | NGM: 258 (13%)IGM: 52 (12%)PDD: 38 (21%) | |
All values are rounded to the nearest integer. ADA, American Diabetes Association; CES-D, Center for Epidemiologic Studies Depression Scale; FG, fasting glucose; FPG, fasting plasma glucose; IFG, impaired fasting glucose; IGR, impaired glucose regulation; IGT, impaired glucose tolerance; M, men; NFG, normal fasting glucose; NGT, normal glucose tolerance; OGTT, oral glucose tolerance test; W, women; WHO, World Health Organization; WHO-5, World Health Organization-5 Wellbeing Index; Zung SDS, Zung Self-Rating Depression Scale.
a% unadjusted for age and sex.
b% differ from reported % in article; presence of missing values or calculation errors unclear.
cValues reported before multiple imputation.
dConverted from mg/dL to mmol/L.
eData obtained through correspondence with the authors.
fThe FG differed significantly between the UDD and PDD groups (P < 0.001).