Frequency of diabetes in family members of probands with non‐insulin‐dependent diabetes mellitus

Abstract. Objectives. To describe the prevalence of known diabetes in a multi‐ethnic community in South Auckland, New Zealand, in relation to family history of diabetes and past history of diabetes in pregnancy. Design. A cross‐sectional, household survey comparing ascertainment with local general practice diabetes registers where they existed. Setting. An inner‐city community with a high proportion of Maori, Pacific Islands people and Europeans. Subjects. A total of 55518 residents (91% response). Comparison with diabetes registers showed 91% ascertainment of known diabetic residents. More detailed interviews with 176/214 (82%) Europeans, 286/336 (85%) Maori and 495/585 (85%) Pacific Islands people with known diabetes. Fifty subjects had insulin‐dependent diabetes mellitus on clinical criteria and were excluded from analyses. Main outcome measures. Prevalence of diabetes. Results. Those with non‐insulin‐dependent diabetes mellitus were more likely to have a diabetic mother than father (Europeans, 21.7% vs. 9.9%; Maori, 17.6 vs. 11.4%; Pacific Islands, 15.7 vs. 5.3%). Diabetic women had a similar likelihood of having a diabetic father as diabetic men but were 1.84 times as likely to have a diabetic mother (95% CI, 1.27–2.69). Diabetic women with past diabetes in pregnancy had 2.05 (95% CI, 1.01–4.15) times the chance of a diabetic offspring as women who had not had past diabetes in pregnancy, who in turn had 2.69 (95% CI, 1.17–6.18) times the likelihood of having a diabetic offspring as diabetic men. Conclusions. The mother is a more important conduit for inheritance of diabetes than the father in these three ethnic groups. A history of diabetes in pregnancy confers an extra risk to the offspring above this usual maternal excess. 1995 Blackwell Publishing Ltd