Background: The prognostic importance of carotid atherosclerosis in individuals with diabetes is unsettled. We aimed to evaluate the relationships between parameters of carotid atherosclerosis and the future occurrence of micro- and cardiovascular complications in individuals with type 2 diabetes.
Methods: Ultrasonographic parameters of carotid atherosclerosis, intima-media thickness (CIMT) and plaques, were measured at baseline in 478 participants who were followed-up for a median of 10.8 years. Multivariate Cox analysis was used to examine the associations between carotid parameters and the occurrence of microvascular (retinopathy, renal, and peripheral neuropathy) and cardiovascular complications (total cardiovascular events [CVEs] and cardiovascular mortality), and all-cause mortality. The improvement in risk stratification was assessed by using the C-statistic and the integrated discrimination improvement (IDI) index.
Results: During follow-up, 116 individuals had a CVE and 115 individuals died (56 from cardiovascular diseases); 131 newly-developed or worsened diabetic retinopathy, 156 achieved the renal composite outcome (94 newly developed microalbuminuria and 78 deteriorated renal function), and 83 newly-developed or worsened peripheral neuropathy. CIMT, either analysed as a continuous or as a categorical variable, and presence of plaques predicted CVEs occurrence and renal outcomes, but not mortality or other microvascular complications. Individuals with an increased CIMT and plaques had a 1.5- to 1.8-fold increased risk of CVEs and a 1.6-fold higher risk of renal outcome. CIMT and plaques modestly improved cardiovascular risk discrimination over classic risk factors, with IDIs ranging from 7.8 to 8.4%; but more markedly improved renal risk discrimination, with IDIs from 14.8 to 18.5%.
Conclusions: Carotid atherosclerosis parameters predicted cardiovascular and renal outcomes, and improved renal risk stratification. Ultrasonographic carotid imaging may be useful in type 2 diabetes management.
Keywords: Cardiovascular outcomes; Carotid intima-media thickness; Carotid plaques; Microvascular complications; Mortality; Renal outcomes; Type 2 diabetes.