Background: In a study of 531 participants with type 2 diabetes (mean age 62.4 years, 54% males, median diabetes duration 3.0 years) in Phase 1 of the community-based Fremantle Diabetes Study (FDS1) conducted between 1993 and 2001 and representing 2,893 patient-years of follow-up [1], the median HbA1c triggering progression from diet to oral hypoglycaemic agents (OHAs) was 7.7% (63 mmol/mol; n=97) and from diet/OHA to insulin was 9.4% (79 mmol/mol; n=45), with reductions to 7.4% (57 mmol/mol) and 7.9% (63 mmol/mol), respectively (P≤0.001) and no increase in hypoglycaemia during up to one year of follow-up. The aim of the present study was to repeat the analysis in 930 Phase 2 (FDS2) participants (mean age 65.7 years, 52% males, median duration 9.0 years) with valid data from baseline and two biennial reviews between 2008 and 2015.
Results: During 3,922 patient-years, 84 FDS2 participants progressed from diet to OHAs and 85 from diet/OHAs to insulin. Median HbA1c levels before OHAs or insulin were started were 6.9% (52 mmol/mol) and 7.8% (62 mmol/mol), respectively. At next biennial review, HbA1c levels were 6.8% (51 mmol/mol) and 7.6% (60 mmol/mol), respectively (P=0.83 and P=0.34 vs baseline). Insulin initiation was associated with an increase in minor but not major hypoglycaemia in the previous year.
Conclusions: Reflecting factors such as the greater range of OHAs and more reliably absorbed basal insulins, as well as care plans, there has been a reduction in the glycaemic thresholds triggering treatment intensification between FDS Phases. However, the glycaemic effect of treatment intensification in FDS2 was much less than in FDS1 and, in the case of insulin, there was an increase in non-severe hypoglycaemia. Notwithstanding individualisation of glycaemic targets, more Australians with type 2 diabetes have been achieving optimal control (HbA1c ≤7.0% or 53 mmol/mol) over the 15 years between FDS Phases.