IFG development in Japanese different to other ethnicities
MedWire News: Reduced insulin secretion plays a greater role in the development of impaired fasting glucose (IFG) in Japanese individuals than increased insulin resistance, study findings demonstrate.
Previous studies have shown insulin resistance to be the "more important factor in Caucasians, Mexican Americans, and Pima Indians," write Mitsuo Fukushima (Kyoto University, Japan) and team.
This, they say, suggests that ethnicity-specific differences in the mechanisms of diabetes mellitus development exist.
In the study, 1383 Japanese individuals with a mean age of 51 years underwent oral glucose tolerance testing.
All were assessed for insulin secretory capacity, defined by insulinogenic index, and insulin sensitivity, defined as insulin sensitivity index composite of IFG/normal glucose tolerance (NGT).
Participants were divided into two groups: those with normal postchallenge glucose (NGT <140 mg/dL; n=1123) and those with elevated postchallenge glucose (≥140 mg/dL; n=260).
Those in the former group were further classified according to fasting plasma glucose: normal fasting glucose (n=594), IFG of 100-109 mg/dL (n=369), and IFG of 110-125 mg/dL (n=160).
Participants with elevated postchallenge glucose were further classified as having glucose levels reflecting impaired fasting glucose (140-200 mg/dL; n=225) or diabetes mellitus (>200 mg/dL; n=35).
The findings, published in the Journal of Diabetes Investigation, show that among IFG participants, insulin secretion rates were positively associated with postchallenge plasma glucose. Specifically, individuals with diabetes had the lowest insulin secretion rate of all participants with IFG.
Insulin sensitivity, reflecting insulin resistance, showed a similar positive association with postchallenge plasma glucose. However, this association was weaker than that seen between insulin secretion and postchallenge glucose.
Given that some individuals with normal postchallenge glucose levels had evidence of IFG, the authors advise that Japanese individuals with IFG levels that fall within NGT parameters, may benefit from additional glucose testing.
This, conclude Fukushima et al, will ensure the accurate identification of glucose tolerance impairment in these individuals.
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By Lauretta Ihonor