The Cambridge Risk Score (CRS) was developed to screen for type 2 diabetes mellitus risk. We assessed the ability of the CRS to predict glycosylated hemoglobin (HbA1c) levels and determined whether the CRS was better than body mass index (BMI) at predicting HbA1c levels in midlife.
We included 7452 participants without known diabetes in a biomedical survey of the 1958 British Birth Cohort at 45 years of age. Receiver operator characteristic curves were used to compare the ability of the CRS and BMI to identify individuals with elevated HbA1c levels using thresholds of 7.0% or more, 6.0% or more, and 5.5% or more.
Of the total sample, 0.9% (95% confidence interval [CI], 0.7%-1.1%) had HbA1c levels of 7.0% or more; 3.8% (95% CI, 3.2%-4.5%), 6.0% or more; and 24.4% (95% CI, 23.1%-25.9%), 5.5% or more. The CRS detected individuals with elevated HbA1c levels with reasonable accuracy (area under the curve, 0.84 for HbA1c level ≥7.0%; 0.76 for HbA1c level ≥6.0%). Similar area under the curve values were obtained using BMI alone (0.84 for HbA1c level ≥7.0%; 0.79 for HbA1c level ≥6.0%). When tested using the lower HbA1c threshold of 5.5% or more, the CRS and BMI did not perform well (areas under the curve, 0.65 and 0.63 for CRS and BMI, respectively). Both measures indicated that approximately 20% of the cohort were at increased risk of diabetes. Owing to the low prevalence of diabetes at 45 years of age, only 2% to 3% of those considered at risk had elevated HbA1c levels.
For a population in mid-adult life, the CRS identified individuals with elevated HbA1c levels reasonably well. However, the CRS had no advantage compared with BMI alone in identifying diabetes risk.