Table 2

Criteria for predicting type 1 diabetes—single criteria

Cut-offAuthor (year)NPer cent
C-pep neg
Sens (%)Spec (%)Mean sens and specPer cent correctPPVNPV
(i) Age at diagnosis (a/d)
<20Boyle (1999)36137209759923694
≤30Prior (1991)57561848283838877
<30Nielsen (1986)21569648876729253
<30Ekpebegh (2013)7149577265656763
<39Shields (2010)7256689783819670
≤40Prior (1991)57561975978827992
≤40Welborn (1983)12121848585856095
≤40Welborn (1981)20124768179795592
≤40Laakso* (1987)17167617970678544
<45Boyle (1999)36137655761571096
(ii) Insulin treatment/time to insulin (tti) (a=all treatments, i=insulin-treated only)
on insulin (a)Prior (1991)57561992562706897
on insulin (a)Welborn (1981)2012410070857749100
on insulin (a)Boyle (1999)36137916176631599
tti≤1.5 m (i)Shields (2010)7256805668697069
tti<1y (a)Prior (1991)57561927584858585
tti<2y (a)Welborn (1983)1212110082918660100
tti≤2y (i)Laakso* (1987)9067708678759158
(iii) BMI
<20Boyle (1999)36137109854923394
<25†Prior (1991)57561349263578747
<25Boyle (1999)36137418664831895
<27Prior (1991)57561876375787976
≤27Welborn (1983)12121806774693893
≤27Laakso* (1987)9067766671738257
<28Balasumbryaman (2006)29460678677787977
<29Boyle (1999)36137715764581196
<29Shields (2010)7256785667686967
<30Ekpebegh (2013)7149774762625968
  • Sensitivity (sens), specificity (spec), proportion correctly classified (%correct), mean of sensitivity and specificity (mean sens and spec), positive predictive value (PPV), and negative predictive value (NPV) for (i) age at diagnosis, (ii) body mass index (BMI) and (iii) insulin treatment and/or time to insulin. Proportion of C-peptide negative patients (% C-pep neg) shown to aid interpretation of % correct, PPV and NPV. Criteria with a mean sensitivity and specificity >70% are highlighted in bold.

  • *Male and female values combined, using postglucagon-stimulated results.

  • †Converted from percentage desirable weight.