Does undiagnosed diabetes mitigate the association between diabetes and cognitive impairment? Findings from the <scp>ELSI‐Brazil</scp> study

Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment. However, most of the evidence has been based on self-reported T2DM, and undiagnosed diabetes has not been considered as a separate category. We aimed to examine the extent to which undiagnosed diabetes modifies the association between diabetes and cognitive impairment in a representative sample of Brazilian adults aged 50 years and older.We analyzed baseline data from 1944 participants of the Brazilian Longitudinal Study of Aging (ELSI-Brazil) conducted from 2015 to 2016. Diabetes was evaluated based on self-reported doctor diagnosis and glycosylated hemoglobin levels. Participants were classified as diabetics (D), undiagnosed diabetics (UDD), or nondiabetics (ND). Cognitive function was assessed by word list learning and verbal fluency tests. Three multiple logistic regression models were used to evaluate the changes in the strength of the associations.Participants with diabetes had 49% greater odds of exhibiting impaired memory than nondiabetics (odds ratio [OR] = 1.49; 95% CI: 1.01-2.20). By combining UDD and ND, the association between diabetes and impaired memory was attenuated by 2.0%, losing its statistical significance (OR = 1.46; 95% CI: 0.98-2.17). By combining UDD and D, the association was attenuated by 7.4% (OR = 1.38; 95% CI: 1.01-1.90). No significant association was found between T2DM and impaired verbal fluency.This study found an association between T2DM and impaired memory but not with impaired verbal fluency. When UDD individuals are considered diabetics, this association is attenuated; when UDD individuals are considered as ND, this association is attenuated to the extent that it loses its statistical significance, affecting thus the clinical interpretation.背景: 2型糖尿病(Type 2 diabetes mellitus,T2DM)与认知功能障碍有关。然而, 大多数证据都是基于自我报告的T2DM, 而未诊断的糖尿病并未被认为是一个单独的类别。我们的目的是在50岁及以上巴西成年人的代表性样本中,研究未诊断的糖尿病在多大程度上改变了糖尿病和认知障碍之间的关联。 方法: 我们分析了从2015年到2016年巴西老龄化纵向研究 (Longitudinal Study of Aging, ELSI)中1 944名参与者的基线数据。根据自我报告的医生诊断和糖化血红蛋白水平, 对糖尿病进行评估。参与者被分为糖尿病患者(D)、未确诊糖尿病的患者(UDD)或非糖尿病患者(ND)。认知功能评估采用词汇表学习和语言流利性测试。三个多元logistic回归模型被用来评估关联强度的变化。 结果: 糖尿病患者比非糖尿病患者记忆受损的几率高49%( OR=1.49; 95% CI1.01~2.20)。联合考虑UDD和ND后, 糖尿病与记忆损害的关联性降低2.0%, 失去统计学意义(OR=1.46; 95% CI 0.98~2.17)。联合考虑UDD和D, 这种关联减弱了7.4%(OR=1.38; 95% CI 1.01~1.90)。未发现T2DM与语言流畅性受损之间存在显著关联。 结论: 本研究发现T2DM与记忆受损有关, 但与语言流畅性受损无关。当UDD个体被认为是糖尿病患者时, 这种关联被减弱; 当UDD个体被认为是ND时, 这种关联被减弱到失去其统计学意义的程度, 从而影响临床解释。.