Clinical risk factors, DNA variants, and the development of type 2 diabetes.
BACKGROUND
Type 2 diabetes mellitus is thought to develop from an interaction between environmental and genetic factors. We examined whether clinical or genetic factors or both could predict progression to diabetes in two prospective cohorts.


METHODS
We genotyped 16 single-nucleotide polymorphisms (SNPs) and examined clinical factors in 16,061 Swedish and 2770 Finnish subjects. Type 2 diabetes developed in 2201 (11.7%) of these subjects during a median follow-up period of 23.5 years. We also studied the effect of genetic variants on changes in insulin secretion and action over time.


RESULTS
Strong predictors of diabetes were a family history of the disease, an increased body-mass index, elevated liver-enzyme levels, current smoking status, and reduced measures of insulin secretion and action. Variants in 11 genes (TCF7L2, PPARG, FTO, KCNJ11, NOTCH2, WFS1, CDKAL1, IGF2BP2, SLC30A8, JAZF1, and HHEX) were significantly associated with the risk of type 2 diabetes independently of clinical risk factors; variants in 8 of these genes were associated with impaired beta-cell function. The addition of specific genetic information to clinical factors slightly improved the prediction of future diabetes, with a slight increase in the area under the receiver-operating-characteristic curve from 0.74 to 0.75; however, the magnitude of the increase was significant (P=1.0x10(-4)). The discriminative power of genetic risk factors improved with an increasing duration of follow-up, whereas that of clinical risk factors decreased.


CONCLUSIONS
As compared with clinical risk factors alone, common genetic variants associated with the risk of diabetes had a small effect on the ability to predict the future development of type 2 diabetes. The value of genetic factors increased with an increasing duration of follow-up.
Lyssenko
Valeriya
V
Department of Clinical Sciences, Lund University, Malmö, Sweden. valeri.lyssenko@med.lu.se
Jonsson
Anna
A
Almgren
Peter
P
Pulizzi
Nicoló
N
Isomaa
Bo
B
Tuomi
Tiinamaija
T
Berglund
Göran
G
Altshuler
David
D
Nilsson
Peter
P
Groop
Leif
L
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D011506:Proteins / Q000235:genetics*; D012372:ROC Curve; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013548:Sweden; D000637:Transaminases / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D011506:Proteins; D000637:Transaminases