Background: We studied cognitive performance in prediabetes (PD) and diabetes mellitus (DM) in males and females.

Methods: A population of 1,895 males and 2,249 non-pregnant females aged 20-59 with data on the Symbol Digit Substitution Test (SDST) and DM status and no history of stroke, depression, or recreational drug use were included in this secondary analysis of NHANES III (1988-1994). Diabetic status, as determined by FPG, in mg/dl, was categorized into Normal (70-99), PD (100-125), and DM (≥126 or HbA1c > 6.5% or medication use). Cognitive performance was measured using a computer-based SDST, commonly used to assess frontal lobe-related functions. Multivariate linear regression models were run using an inverse transformed SDST score (digits/90 sec) and adjusted for confounders and study design in 3 additive models listed in Table 1.

Results: The mean (SE) SDST score (in digits/90 sec) was 36.9 (0.3) for females and 35.2 (0.3) for males. DM males matched, on average, 4.02 fewer digits than normals. This association did not hold after adjustment in Model 2 and 3. PD males, however, significantly matched 1.16 fewer digits than normals even after adjustment. Although PD and DM females also had lower SDST scores compared to normals, the difference lost significance after adjustment.

Conclusion: PD and DM did poorer on SDST than normals. Males seem to be more affected cognitively by impaired glucose tolerance than females.


A. Visaria: None. L.F. Amorosa: None.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at