DIFFERENCES IN PLASMA-INSULIN RESPONSES IN URBAN AND RURAL INDIANS - A STUDY IN SOUTHERN INDIANS

Fasting and 2 h post glucose plasma immunoreactive insulin (fasting IR I and 2 h IRI) responses were measured in urban (n = 149) and rural (n = 40) individuals with normal glucose tolerance during an epidemiolog ical survey. In this survey, 900 urban and 1038 rural subjects were sc reened for glucose intolerance by capillary blood sampling. The respec tive response rates were 91 % and 88 %. We had planned to collect veno us blood for IRI estimation, i.e. from 180 urban and 200 rural subject s. The compliance for the same was poor from the rural subjects and th erefore the number available for IRI estimation was small. The mean +/ - SD ages of the urban and rural groups were similar (35.3 +/- 9.9 and 38.6 +/- 13.1 years, respectively). The rural population had lower bo dy mass index (BMI) and subscapular:triceps ratio compared to the urba n group (p < 0.001). The total calorie consumption was lower and physi cal activity was higher in rural population. Fasting and 2 h insulin v alues in urban population were 16.6 +/- 9.4 mU l-1 and 60.6 +/- 42.5 m U l-1 and in rural 6.7 +/- 5.1 mU l-1 and 32.4 +/- 27.8 mU l-1, respec tively; the values being significantly lower in the rural population ( p < 0.001). Multiple regression analysis showed that in urban populati on the fasting insulin was correlated to the BMI and the 2h IRI to 2 h glucose, BMI and the subscapular:triceps ratio. In the rural populati on, similar results were obtained, except in that the 2 h IRI was infl uenced by the gender also. This study showed that the fasting IRI and 2 h IRI responses in normoglycaemic urban and rural populations differ ed widely, probably related to the differences in body mass and adipos ity distribution. The higher IRI concentrations in normoglycaemic urba n subjects suggest a relative insulin resistance and this may be a con tributory factor for the higher prevalence of diabetes in urban Indian s.