Diabetes Care, Vol 19, Issue 1 67-69, Copyright © 1996 by American Diabetes Association
Nondiabetic Mexican-Americans do not have reduced insulin responses relative to nondiabetic non-Hispanic whites
SM Haffner, H Miettinen and MP Stern
Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78284-7873, USA.
OBJECTIVE: To study why Mexican-Americans have a threefold increase in
NIDDM relative to non-Hispanic whites. The etiology of NIDDM is still
controversial, with both insulin resistance and decreased insulin secretion
proposed as precursors of NIDDM. RESEARCH DESIGN AND METHODS: We examined
possible ethnic differences in fasting insulin (as a marker of insulin
resistance) and change in insulin-to-change in glucose ratio (delta
I30:delta G30) during the first 30 min after oral glucose ingestion (as a
marker of abnormal whites from the San Antonio Heart Study, a
population-based study of diabetes and cardiovascular disease. Fasting
insulin and delta I30:delta G30 were evaluated as continuous variables.
RESULTS: Mexican-Americans had increased insulin concentrations at fasting
and 30, 60, and 120 min after an oral glucose load as well as an increased
0- to 30-min increment in insulin and delta I30:delta G30 relative to
non-Hispanic whites. These results remained unchanged after adjustment for
age, sex, obesity, body fat distribution, and glucose tolerance.
CONCLUSIONS: These results suggest that increased insulin resistance rather
than decreased insulin secretion is characteristic of nondiabetic
Mexican-Americans, a high-risk population for NIDDM.