Association of frailty index with congestive heart failure, all-cause and cardiovascular mortality among individuals with type 2 diabetes: a study from National Health and Nutrition Examination Surveys (NHANES), 1999–2018

BACKGROUND: Both type 2 diabetes mellitus (T2DM) and frailty are strongly associated with congestive heart failure (CHF). Individuals with T2DM and CHF have a high frailty burden. The association of frailty with HF, all-cause, and cardiovascular mortality in patients with T2DM has not been thoroughly explored. METHODS: This study included 2894 adults with T2DM from the National Health and Nutrition Examination Survey (NHANES) database over ten cycles (1999–2018) and followed up for all-cause and cardiovascular mortality through 31 December 2019. The frailty index (FI) was calculated using a 46-item deficit model to assess frailty status. Weighted multivariable logistic regression was performed to explore the relationship between frailty and CHF in patients with T2DM. Weighted restricted cubic splines were used to evaluate the non-linear relationship between FI and outcome. All-cause mortality and cardiovascular mortality association with FI was assessed using the Kaplan–Meier curve and COX proportional hazards regression accounting for sampling weights. Subgroup and sensitivity analyses were performed to evaluate the robustness of the results. RESULTS: After the adjustment of essential confounders, a higher frailty index in T2DM was associated with increased odds of CHF (odds ratio [OR] for per 1-SD increase, 2.02, 95% confidence interval [CI] 1.67–2.45; P < 0.0001). The presence of frailty T2DM (OR, 3.60; 95% CI 2.34–5.54; P < 0.0001) was associated with a significant increase in the prevalence of CHF compared to non-frailty T2DM in a fully adjusted model. During the median follow-up of 6.75 years, per 1-SD increase in FI was associated with a 41% higher risk of all-cause mortality and a 30% higher risk of cardiovascular mortality after being adjusted for all confounders. Similar results were observed when sensitivity analyses were performed. There was also a non-linear relationship between FI and all-cause mortality. In a weighted multivariate COX proportional model adjusted for full confounders, frailty T2DM increased all-cause (HR, 1.86; 95% CI 1.55–2.24; P < 0.0001) and cardiovascular (HR 1.66; 95% CI 1.18–2.33; P = 0.003) mortality and compared to non-frailty T2DM. The positive association of frailty index and all-cause mortality was only in participants without CHF. The positive association of frailty index and cardiovascular mortality was only in non-anti-diabetic drug users. CONCLUSIONS: Frailty index in T2DM was positively associated with CHF in linear fashions. The Frailty index was positively correlated with all-cause and cardiovascular death in patients with T2DM. Frailty T2DM was positively associated with CHF, all-cause mortality, and cardiovascular mortality compared to non-frailty T2DM. Promoting frailty measurement and management in T2DM may be beneficial to reduce the burden of CHF and mortality. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13098-023-01165-z.