Twice- rather than once-daily basal insulin is associated with better glycaemic control in Type 1 diabetes mellitus 12 months after skills-based structured education in insulin self-management

Abstract

Aim: This study investigates the relationship between basal insulin regimen and glycaemic outcomes 12 months after skills-based structured education in the UK Dose Adjustment for Normal Eating (DAFNE) programme for Type 1 diabetes mellitus. Method: Retrospective analysis of data from 892 DAFNE participants from 11 UK centres. Results: Mean HbA1c 12 months after DAFNE was lower in those using twice- rather than once-daily basal insulin after correcting for differences in baseline HbA1c, age and duration of diabetes; difference -2 (95% CI -3 to -1) mmol/mol [-0.2 (-0.3 to -0.1)%], P = 0.009. The greatest fall in HbA1c of -5 (-7 to -3) mmol/mol [-0.4 (-0.6 to -0.3)%], P < 0.001 occurred in those with less good baseline control, HbA1c ≥ 58 mmol/mol, who switched from once- to twice-daily basal insulin. There was no difference in the 12-month HbA1c between users of glargine, detemir and NPH insulin after correcting for other variables. Relative risk of severe hypoglycaemia fell by 76% and ketoacidosis by 63% 12 months after DAFNE. The rate of severe hypoglycaemia fell from 0.82 to 0.23 events/patient year in twice-daily basal insulin users. In the group with greatest fall in HbA1c, the estimated relative risk for severe hypoglycaemia in twice-daily basal insulin users versus once daily at 12 months was 1.72 (0.88-3.36, P = 0.110). Conclusion: After structured education in adults with Type 1 diabetes mellitus, use of basal insulin twice rather than once daily was associated with lower HbA1c, independent of insulin type, with significant reductions in severe hypoglycaemia and ketoacidosis in all groups. What's new?: In people with Type 1 diabetes mellitus a once-daily basal insulin regimen is sometimes used instead of the evidence-based twice-daily regimen during structured education. This retrospective study demonstrates lower HbA1c in twice-daily basal insulin users after Dose Adjustment for Normal Eating (DAFNE) education. Benefit in reduced severe hypoglycaemia and ketoacidosis is not influenced by basal insulin frequency or type. Consistency of mealtime insulin replacement and basal insulin dose-adjustment training may allow differences to be detected in this study in contrast to recent reports showing no effect of basal insulin frequency on HbA1c.