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Incidence of type 2 diabetes in pre-diabetic Japanese individuals categorized by HbA1c levels: a historical cohort study.

Kawahara T, Imawatari R, Kawahara C, Inazu T, Suzuki G - PLoS ONE (2015)

Bottom Line: Reported incidence of type 2 diabetes estimated at the pre-diabetic stage differs widely (2.3-18.1% per year).A historical cohort study using electronic medical record data obtained between January 2008 and December 2013.During the follow-up period (mean 3.7 years), 4,369 participants developed diabetes.

View Article: PubMed Central - PubMed

Affiliation: Kokura Medical Association Health Testing Center, Kitakyushu, Fukuoka, Japan.

ABSTRACT

Objective: Reported incidence of type 2 diabetes estimated at the pre-diabetic stage differs widely (2.3-18.1% per year). Because clinicians need to know the risk of incident diabetes after a diagnosis of pre-diabetes, our objective was to estimate precise incidence of diabetes using baseline HbA1c levels.

Methods: A historical cohort study using electronic medical record data obtained between January 2008 and December 2013. A total of 52,781 individuals with HbA1c < 6.5% were assigned to one of six groups categorized by baseline HbA1c level: ≤ 5.5% (n=34,616), 5.6-5.7% (n=9,388), 5.8-5.9% (n=4,664), 6.0-6.1% (n= 2,338), 6.2-6.3% (n=1,257), and 6.4% (n=518). Participants were tracked until a subsequent diagnosis of diabetes or end of follow-up during a period of 5 years.

Results: During the follow-up period (mean 3.7 years), 4,369 participants developed diabetes. The incidence of diabetes in the first year was 0.7, 1.5, 2.9, 9.2, 30.4, and 44.0% in the six HbA1c groups, respectively. At five years the incidence was 3.6, 8.9, 13.8, 27.5, 51.6, and 67.8%, respectively (p < 0.0001 comparing the HbA1c ≤5.5% group to the other groups). After adjustment for confounding factors, the hazard ratios compared with the HbA1c ≤5.5% group were significantly elevated: 2.3 (95%CI 2.0-2.5), 3.4 (95%CI 2.9-3.7), 8.8 (95%CI 8.0-10.1), 26.3 (95%CI 23.3-30.1), and 48.7 (95%CI 40.8-58.1) in the five HbA1c groups (p < 0.0001).

Conclusion: By fractionating baseline HbA1c levels into narrower HbA1c range groups, accuracy of estimating the incidence of type 2 diabetes in subsequent years was increased. The risk of developing diabetes increased with increasing HbA1c levels, especially with the HbA1c level ≥ 6.2% in the first follow-up year.

No MeSH data available.


Related in: MedlinePlus

Kaplan—Meier survival curves for incident diabetes during the 5-year study period, differentiated by baseline HbA1c levels.Each curve had a significantly higher risk compared with the reference group, the curve for HbA1c ≤ 5.5% (log-rank P value <0.0001).
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pone.0122698.g001: Kaplan—Meier survival curves for incident diabetes during the 5-year study period, differentiated by baseline HbA1c levels.Each curve had a significantly higher risk compared with the reference group, the curve for HbA1c ≤ 5.5% (log-rank P value <0.0001).

Mentions: Fig 1 presents Kaplan—Meier curves of diabetes-free probability based on the baseline HbA1c categories. Compared with the reference group (HbA1c ≤ 5.5%), the other groups had significantly lower diabetes-free probability (log-rank P values < 0.0001). Each group was also significantly different from the other groups (log-rank P values < 0.0001). Diabetes incidence during the first follow-up year was 0.7, 1.5, 2.9, 9.2, 30.4, and 44.0% for the baseline HbA1c ≤ 5.5, 5.6–5.7, 5.8–5.9, 6.0–6.1, 6.2–6.3, and 6.4% groups, respectively. Incidence over the entire follow-up period was 3.6, 8.9, 13.8, 27.5, 51.6, and 67.8% for the same groups. The increment of incidence was steeper in the two groups with HbA1c ≥ 6.2% (6.2–6.3 and 6.4% groups), especially in the first follow-up year (p ≤ 0.0093, S1 Text). Since the rate of revisit in each subsequent year was greater than 99% in every HbA1c group (data not shown), and because rate of loss to follow-up over 5 years did not differ significantly among HbA1c groups (S2 Table), incidence rates would not be biased by participation rate.


Incidence of type 2 diabetes in pre-diabetic Japanese individuals categorized by HbA1c levels: a historical cohort study.

Kawahara T, Imawatari R, Kawahara C, Inazu T, Suzuki G - PLoS ONE (2015)

Kaplan—Meier survival curves for incident diabetes during the 5-year study period, differentiated by baseline HbA1c levels.Each curve had a significantly higher risk compared with the reference group, the curve for HbA1c ≤ 5.5% (log-rank P value <0.0001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390315&req=5

pone.0122698.g001: Kaplan—Meier survival curves for incident diabetes during the 5-year study period, differentiated by baseline HbA1c levels.Each curve had a significantly higher risk compared with the reference group, the curve for HbA1c ≤ 5.5% (log-rank P value <0.0001).
Mentions: Fig 1 presents Kaplan—Meier curves of diabetes-free probability based on the baseline HbA1c categories. Compared with the reference group (HbA1c ≤ 5.5%), the other groups had significantly lower diabetes-free probability (log-rank P values < 0.0001). Each group was also significantly different from the other groups (log-rank P values < 0.0001). Diabetes incidence during the first follow-up year was 0.7, 1.5, 2.9, 9.2, 30.4, and 44.0% for the baseline HbA1c ≤ 5.5, 5.6–5.7, 5.8–5.9, 6.0–6.1, 6.2–6.3, and 6.4% groups, respectively. Incidence over the entire follow-up period was 3.6, 8.9, 13.8, 27.5, 51.6, and 67.8% for the same groups. The increment of incidence was steeper in the two groups with HbA1c ≥ 6.2% (6.2–6.3 and 6.4% groups), especially in the first follow-up year (p ≤ 0.0093, S1 Text). Since the rate of revisit in each subsequent year was greater than 99% in every HbA1c group (data not shown), and because rate of loss to follow-up over 5 years did not differ significantly among HbA1c groups (S2 Table), incidence rates would not be biased by participation rate.

Bottom Line: Reported incidence of type 2 diabetes estimated at the pre-diabetic stage differs widely (2.3-18.1% per year).A historical cohort study using electronic medical record data obtained between January 2008 and December 2013.During the follow-up period (mean 3.7 years), 4,369 participants developed diabetes.

View Article: PubMed Central - PubMed

Affiliation: Kokura Medical Association Health Testing Center, Kitakyushu, Fukuoka, Japan.

ABSTRACT

Objective: Reported incidence of type 2 diabetes estimated at the pre-diabetic stage differs widely (2.3-18.1% per year). Because clinicians need to know the risk of incident diabetes after a diagnosis of pre-diabetes, our objective was to estimate precise incidence of diabetes using baseline HbA1c levels.

Methods: A historical cohort study using electronic medical record data obtained between January 2008 and December 2013. A total of 52,781 individuals with HbA1c < 6.5% were assigned to one of six groups categorized by baseline HbA1c level: ≤ 5.5% (n=34,616), 5.6-5.7% (n=9,388), 5.8-5.9% (n=4,664), 6.0-6.1% (n= 2,338), 6.2-6.3% (n=1,257), and 6.4% (n=518). Participants were tracked until a subsequent diagnosis of diabetes or end of follow-up during a period of 5 years.

Results: During the follow-up period (mean 3.7 years), 4,369 participants developed diabetes. The incidence of diabetes in the first year was 0.7, 1.5, 2.9, 9.2, 30.4, and 44.0% in the six HbA1c groups, respectively. At five years the incidence was 3.6, 8.9, 13.8, 27.5, 51.6, and 67.8%, respectively (p < 0.0001 comparing the HbA1c ≤5.5% group to the other groups). After adjustment for confounding factors, the hazard ratios compared with the HbA1c ≤5.5% group were significantly elevated: 2.3 (95%CI 2.0-2.5), 3.4 (95%CI 2.9-3.7), 8.8 (95%CI 8.0-10.1), 26.3 (95%CI 23.3-30.1), and 48.7 (95%CI 40.8-58.1) in the five HbA1c groups (p < 0.0001).

Conclusion: By fractionating baseline HbA1c levels into narrower HbA1c range groups, accuracy of estimating the incidence of type 2 diabetes in subsequent years was increased. The risk of developing diabetes increased with increasing HbA1c levels, especially with the HbA1c level ≥ 6.2% in the first follow-up year.

No MeSH data available.


Related in: MedlinePlus