The role of BMI across the life course in the relationship between age at menarche and diabetes, in a British Birth Cohort.

AIMS: Previous research showing an inverse association between age of menarche and adult diabetes relied on recalled age at menarche and did not adjust for BMI across the life course. We investigated the relationship between age at menarche and diabetes, and whether childhood, adolescent or adult BMI attenuates this relationship. METHODS: We used data from the Medical Research Council National Survey of Health and Development, a British birth cohort study of men and women born in 1946, with contemporaneous recording of the age of menarche, BMI at 2, 7, 15 and 20-53 years and diabetes status to 53 years. RESULTS: A significant inverse relationship between age at menarche and diabetes [hazard ratio = 0.73 per year older age at menarche (95% CI 0.56-0.96), P = 0.02] was attenuated by adjustment for adult BMI [hazard ratio 0.85 (95% CI 0.65-1.10), P = 0.2]. The effect of age at menarche on Type 2 diabetes was very similar to that for all types of diabetes. Attenuation of the association between age at menarche and diabetes was also observed with BMI at 15 years, but less so with BMI measured earlier in childhood. CONCLUSIONS: Earlier age at menarche is associated with a higher risk of diabetes, and specifically Type 2 diabetes, in later life, which is most strongly attenuated by adolescent and adult adiposity. Early menarche may be clinically useful in identifying women who are at risk of later adiposity and so of developing Type 2 diabetes.

Undiagnosed diabetes-data from the English longitudinal study of ageing.

AIMS: Diabetes UK estimates a quarter of UK cases of diabetes are undiagnosed; 750,000 people have undiagnosed diabetes in addition to 2.25 million with known diabetes, but research studies examining this are contradictory. The aim was to determine the prevalence of, and risk factors for, undiagnosed diabetes in the population of England aged > 50 years and to calculate the percentage of cases of undiagnosed diabetes. METHODS: This was a cross-sectional study in a nationally representative sample of 6739 people aged 52-79 years from the English Longitudinal Study of Ageing (ELSA) 2004/2005. Diabetes cases were ascertained by self-reported doctor diagnosis of diabetes. A fasting plasma glucose measurement after a minimum of 8-h fast was available for 2387 (38% of the participants without diabetes). Undiagnosed diabetes cases were based on a fasting plasma glucose >or= 7.0 mmol/l. RESULTS: The overall weighted prevalence of diabetes was 9.1%; 502 people (7.5%) had self-reported diabetes (9.0% of men and 6.0% of women); 36 (1.7%) had undiagnosed diabetes (2.6% of men and 0.8% of women). Of cases of diabetes, 18.5% were undiagnosed (22% in men, 12% in women). Significant risk factors for undiagnosed diabetes were male sex, higher body mass index, waist circumference, systolic blood pressure and triglycerides. CONCLUSIONS: In 2004 the prevalence of undiagnosed diabetes, and the proportion of cases of diabetes that were undiagnosed, appear smaller than in previous studies. This is likely to be due to increased awareness of diabetes and improved clinical care resulting in many of those with previously undetected disease having been diagnosed.