November 29, 2016
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Prediabetes increases CVD, all-cause mortality risk

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The risk for cardiovascular disease and all-cause mortality is increased among people with a fasting glucose concentration of at least 5.6 mmol/L or an HbA1c of at least 39 mmol/mol, study data show.

Yunzhao Hu, MD, PhD, professor in the department of cardiology at First People’s Hospital of Shunde in Foshan, China, and colleagues evaluated 53 prospective cohort studies to determine the associations between different definitions of prediabetes and the risks for CVD and all-cause mortality.

Prediabetes was variously defined as fasting glucose of 5.6 mmol/L to 6.9 mmol/L (American Diabetes Association definition for impaired fasting glucose), fasting glucose of 6.1 mmol/L to 6.9 mmol/L (WHO definition for IFG), 2-hour plasma glucose concentration of 7.8 mmol/L to 11 mmol/L during an oral glucose tolerance test (impaired glucose tolerance), HbA1c of 5.7% to 6.4% (ADA criteria) and HbA1c 6% to 6.4% (National Institute for Health and Care Excellence [NICE] guideline). Follow-up for the studies was a median 9.5 years.

Overall, data from 25 studies were used in determining the relationship between prediabetes and risk for all-cause mortality. The risk for all-cause mortality was increased when prediabetes was based on the ADA definition for IFG (RR = 1.13; 95% CI, 1.05-1.25), the WHO definition for IFG (RR = 1.13; 95% CI, 1.05-1.21) or IGT (RR = 1.32; 95% CI, 1.23-1.4). Participants with IGT had a higher risk for all-cause mortality compared with participants in groups according to other definitions of prediabetes (P < .001).

The association between the risk for composite CVD and prediabetes was based on data from 35 studies. The risk for increased composite CV events was increased when prediabetes was defined as the ADA definition for IFG (RR = 1.13; 95% CI, 1.05-1.21), the WHO definition for IFG (RR = 1.26; 95% CI, 1.12-1.41), IGT (RR = 1.3; 95% CI, 1.19-1.42), HbA1c 38.8 mmol/mol to 46.4 mmol/mol (RR = 1.21; 95% CI, 1.01-1.44) or HbA1c 42.11 mmol/mol to 46.4 mmol/mol (RR = 1.25; 95% CI, 1.01-1.55).

The relationship between prediabetes and the risk for coronary heart disease was based on data from 24 studies. CHD risk was increased when prediabetes was defined using the ADA criteria for IFG (RR = 1.1; 95% CI, 1.04-1.16), WHO criteria for IFG (RR = 1.18; 95% CI, 1.08-1.28), IGT (RR = 1.2; 95% CI, 1-1.44), HbA1c 39 mmol/mol to 47 mmol/mol (RR = 1.15; 95% CI, 1.01-1.33) or HbA1c 42 mmol/mol to 47 mmol/mol (RR = 1.28; 95% CI, 1.03-1.59).

The risk for stroke was increased when prediabetes was defined by ADA criteria for IFG (RR = 1.06; 95% CI, 1.01-1.11), WHO criteria for IFG (RR = 1.17; 95% CI, 1.09-1.25) and IGT (RR = 1.2; 95% CI, 1-1.45) after multivariate adjustment.

“The risk increased in people with fasting glucose levels as low as 100 mg/dL and with HbA1c of 5.7%,” Hu told Endocrine Today. “So we believe people with prediabetes should [be followed up clinically] and keep a healthy lifestyle. We need to develop models for risk stratification in people with prediabetes, and we will select higher-risk people with prediabetes to evaluate whether drug treatment can prevent CVDs in them.” – by Amber Cox

For more information:

Yunzhao Hu, MD, PhD, can be reached at huyunzhao4406@163.com.

Disclosure: The researchers report no relevant financial disclosures.