The changes that occur in glucose metabolism before the diagnosis of type 2 diabetes are not known. Data from a prospective cohort study (Whitehall II study) in London, England, have been presented.
The study began in 1985–1988 and included 10,308 people aged 35–55. Oral glucose tolerance tests were performed in 1991–1994, 1997–1999 and 2002–2004. Data were analysed from 6,538 subjects without diabetes at baseline. Diabetes was diagnosed in 505 individuals over an average follow-up of 9.7 years. Among people who developed type 2 diabetes, there was a rapid increase (from 5.79 to 7.4 mmol/L) in fasting blood glucose beginning 3 years before the diagnosis. There was a similar increase (from 7.6 to 11.9 mmol/L) in 2-hour post-load glucose levels at the same time. Homeostasis model assessment (HOMA) insulin sensitivity fell steeply to 86.7% during the 5 years before diagnosis of diabetes. HOMA beta-cell function increased 3 or 4 years before diagnosis and then decreased until diagnosis.
Knowledge of the changes could aid the assessment of diabetes risk.
Tabák AG, et al. Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes: an analysis from the Whitehall II study. Lancet 2009;373:2215–2221: Matthews DR, Levy JC. Impending type 2 diabetes.