Risk of Progression to Diabetes Among Older Adults With Prediabetes

Abstract

Importance: The term prediabetes is used to identify individuals at increased risk for diabetes. However, the natural history of prediabetes in older age is not well characterized.

Objectives: To compare different prediabetes definitions and characterize the risks of prediabetes and diabetes among older adults in a community-based setting.

Design, setting, and participants: In this prospective cohort analysis of 3412 older adults without diabetes from the Atherosclerosis Risk in Communities Study (baseline, 2011-2013), participants were contacted semiannually through December 31, 2017, and attended a follow-up visit between January 1, 2016, and December 31, 2017 (median [range] follow-up, 5.0 [0.1-6.5] years).

Exposures: Prediabetes defined by a glycated hemoglobin (HbA1c) level of 5.7% to 6.4%, impaired fasting glucose (IFG) level (FG level of 100-125 mg/dL), either, or both.

Main outcomes and measures: Incident total diabetes (physician diagnosis, glucose-lowering medication use, HbA1c level ≥6.5%, or FG level ≥126 mg/dL).

Results: A total of 3412 participants without diabetes (mean [SD] age, 75.6 [5.2] years; 2040 [60%] female; and 572 [17%] Black) attended visit 5 (2011-2013, baseline). Of the 3412 participants at baseline, a total of 2497 participants attended the follow-up visit or died. During the 6.5-year follow-up period, there were 156 incident total diabetes cases (118 diagnosed) and 434 deaths. A total of 1490 participants (44%) had HbA1c levels of 5.7% to 6.4%, 1996 (59%) had IFG, 2482 (73%) met the HbA1c or IFG criteria, and 1004 (29%) met both the HbA1c and IFG criteria. Among participants with HbA1c levels of 5.7% to 6.4% at baseline, 97 (9%) progressed to diabetes, 148 (13%) regressed to normoglycemia (HbA1c, <5.7%), and 207 (19%) died. Of those with IFG at baseline, 112 (8%) progressed to diabetes, 647 (44%) regressed to normoglycemia (FG, <100 mg/dL), and 236 (16%) died. Of those with baseline HbA1c levels less than 5.7%, 239 (17%) progressed to HbA1c levels of 5.7% to 6.4% and 41 (3%) developed diabetes. Of those with baseline FG levels less than 100 mg/dL, 80 (8%) progressed to IFG (FG, 100-125 mg/dL) and 26 (3%) developed diabetes.

Conclusions and relevance: In this community-based cohort study of older adults, the prevalence of prediabetes was high; however, during the study period, regression to normoglycemia or death was more frequent than progression to diabetes. These findings suggest that prediabetes may not be a robust diagnostic entity in older age.

Figure 1.. Prevalence of Prediabetes in Older Adults in the Atherosclerosis Risk in Communities Study According to Glycated Hemoglobin (HbA_1c) and Impaired Fasting Glucose (FG) Definitions

Figure 2.. Flowchart (Sankey Plot) Depicting Glycemia Progression, Regression, and Mortality in Older Adults According to Prediabetes Definitions at Baseline

A, Of the participants with glycated hemoglobin (HbA_1c) levels of 5.7% to 6.4% at visit 5, 645 (59%) had HbA_1c-defined prediabetes at visit 6, 97 (9%) progressed to diabetes, 148 (13%) regressed to normoglycemia (HbA_1c, <5.7%), and 207 (19%) died. Of the participants with HbA_1c levels less than 5.7% at visit 5, 239 (17%) progressed to HbA_1c-defined prediabetes at visit 6, 41 (3%) progressed to diabetes, 893 (64%) had normoglycemia at visit 6, and 227 (16%) died. B, Of the participants with impaired fasting glucose (FG levels of 100-125 mg/dL) at visit 5, 467 (32%) had impaired FG at visit 6, 112 (8%) progressed to diabetes, 647 (44%) regressed to normoglycemia (FG, <100 mg/dL), and 236 (16%) died. Of the participants with normoglycemia (FG, <100 mg/dL) at visit 5, 80 (8%) progressed to impaired FG (FG, 100-125 mg/dL) at visit 6, 26 (3%) progressed to diabetes, 731 (71%) had normoglycemia at visit 6, and 198 (19%) died.