Type 1 diabetes in the offspring does not increase the risk of parental type 2 diabetes in South Indians.
OBJECTIVE
(a) To study whether there was an increased prevalence of glucose intolerance in the parents of probands with Type 1 diabetes and (b) to look for any possible link between the glucose intolerance in the parents with HLA-DQB1 alleles transmitted in excess to the Type 1 diabetes offspring. Study Design and Methods From 215 families of South Indian Type 1 diabetes probands, 336 parents (170 fathers, age 30-70 years; 166 mothers, age 23-72 years) were studied by oral glucose tolerance test (GTT). Glucose intolerance in the parents was compared with the population data available. HLA-DQB1 alleles in 170 of the families were studied by the Olerup method (based on sequence specific primers) and the transmission disequilibrium test (TDT) was used to determine the Type 1 diabetes-associated DQB1 alleles.


RESULTS
Among the parents 11.2% had Type 2 diabetes which was similar to the population data of 11.6%. However there was a male predominence among the diabetic parents (chi(2)=7.0, p=0.008), while in the population there was a female predominence. Prevalence of IGT was significantly more among the parents (13.6%) compared with the population data (9.1%) (chi(2)=6.43, p=0.011). Both HLA-DQB1*0201 (p<0.0001) and DQB1*0302 (p=0.0001) were positively associated with Type 1 diabetes in the probands although 21% of the probands possessed neither DQB1*0201 or DQB1*0302. The distribution of glucose tolerance categories in the parents of the probands differed according to the presence of DQB1*0302 (p= 0.035) whilst no such differences existed for DQB1*0201.


CONCLUSIONS
In summary, the presence of Type 1 diabetes in the South Indian offspring does not predict a higher occurrence of Type 2 diabetes in the parents. However, there is an increased occurrence of impaired glucose tolerance (IGT) among the parents. Family based studies demonstrate increased transmission of HLA-DQB1*0201 and HLA-DQB1*0302 with Type 1 diabetes similar to North American and European Caucasian subjects. Furthermore, HLA-DQB1*0302 may be a minor determinant of glucose tolerance in parents of offspring with Type 1 diabetes.
Ramachandran
A
A
Diabetes Research Centre, Madras, India. ramachandran@vsnl.com
Snehalatha
C
C
Tuomilehto-Wolf
E
E
Vidgren
G
G
Ogunkolade
B W
BW
Vijay
V
V
Hitman
G A
GA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000235:genetics* / Q000276:immunology; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000235:genetics* / Q000276:immunology; D005260:Female; D018149:Glucose Intolerance / Q000235:genetics; D005951:Glucose Tolerance Test; D006683:HLA-DQ Antigens / Q000235:genetics; D059866:HLA-DQ beta-Chains; D006801:Humans; D007196:Indiana / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009679:Nuclear Family; D010290:Parents; D015995:Prevalence; D012307:Risk Factors
D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen