RESEARCH DESIGN AND METHODS -The frequencies of diabetes by the 3 sets of criteria were compared in 5,023 adult Pima Indians not taking hypoglycemic drugs. Among nondiabetic subjects, fasting plasma glucose (FPG) and 2-h postload plasma glucose (2-h PG) concentrations and categories of impaired glucose regulation or diabetes were evaluated as predictors of diabetes defined by 1999 WHO criteria.RESULTS -The frequency of diabetes was 12.5% by 1997 ADA criteria, 14.6% by 1985 WHO criteria, and 15.3% by 1999 WHO criteria. The incidence of diabetes was strongly related to higher FPG and 2-h PG, each of which had very similar predictive powers. Impaired glucose tolerance (IGT) was more common than impaired fasting glucose (IFG) (15 vs. 5%), but the 5-year incidence of diabetes was higher in IFG than IGT (37 vs. 24%).CONCLUSIONS -The prevalence and incidence of diabetes are somewhat lower with the ADA criteria than with the 1985 or 1999 WHO criteria. The intermediate categories of glycemia differ substantially. IFG defines a smaller number of people who are at higher risk of developing diabetes than those with IGT. More people at high risk of diabetes could be identified by using either IFG or IGT, as recommended by the 1999 WHO criteria, or by using the FPG concentration alone, but with a lower cutoff value.

The aim of this study was to identify loci influencing susceptibility to microvascular complications (nephropathy and retinopathy) in Pima Indians with type 2 diabetes. Affected sib-pair linkage analyses were performed on 98 diabetic sibling pairs with nephropathy in both members and on 103 sibling pairs with retinopathy in both members. Four chromosomal regions with some evidence of linkage (P < 0.01; logarithm of odds [LOD] >1.18) with nephropathy were identified. The strongest evidence for linkage with nephropathy was on chromosome 7, where two adjacent markers, D7S500 and D7S1804, were linked both by two-point analysis (LOD = 2.73 and LOD = 2.28; respectively) and by multipoint analysis (LOD = 2.04). Additional loci potentially linked to nephropathy were found on chromosome 3, near D3S3053 (multipoint LOD = 1.48); on chromosome 9, near D9S910 (multipoint LOD = 1.12) and D9S302 (two-point LOD = 1.28); and on chromosome 20, near D20S115 (multipoint LOD = 1.83) and GATA65E01 (two-point LOD = 1.89). Multipoint analyses showed two regions with some evidence for linkage to retinopathy: chromosome 3 between D3S3053 and D3S2427 (LOD = 1.36), and chromosome 9 between D9S1120 and D9S910 (LOD = 1.46). These linkage analyses suggest that a genetic element on chromosome 7 and possibly one on chromosome 20 influence susceptibility to diabetic nephropathy but not retinopathy. Genetic elements on chromosome 3 and 9 may determine susceptibility to both these complications. These loci could presumably influence susceptibility to the complications by influencing the microvasculature directly, by influencing the severity of hyperglycemia, or by other unknown mechanisms.

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