Role of the liver in the sustained normalisation of A1c over 2 years following short-term insulin therapy in early type 2 diabetes

Aims: When administered in early type 2 diabetes (T2DM), the strategy of 'induction' with short-term intensive insulin therapy (IIT) followed by 'maintenance' with metformin thereafter can yield outstanding glycaemic control, with some patients achieving A1c in the normal range of its assay. We thus sought to identify determinants of sustained normalisation of A1c in response to this treatment strategy.

Materials and methods: In this study, adults with T2DM of mean duration 1.7 ± 1.4 years received induction IIT (glargine, lispro) for 3 weeks, followed by metformin maintenance either with or without periodic 2-week courses of IIT every 3 months for 2 years. Sustained glycaemic normalisation was defined by A1c <6.0% at 2 years.

Results: Of 101 participants, 26 achieved A1c <6.0% at 2 years. At baseline, these individuals had lower A1c and fasting glucose than the other participants, along with better beta-cell function. During maintenance therapy from 3 weeks to 2 years, they had greater reduction of adiposity (body mass index: p = 0.02; waist circumference: p = 0.02), hepatic insulin resistance (HOMA-IR: p = 0.02) and ALT (p = 0.005), coupled with relative stabilisation of beta-cell function and glycaemia. On logistic regression analyses, significant independent predictors of normalisation of A1c at 2 years were baseline A1c (adjusted odds ratio [aOR] = 0.01 [95% CI 0.001-0.16], p = 0.001) and the changes in waist circumference (aOR = 0.77 [0.63-0.94], p = 0.012) and ALT (aOR = 0.90 [0.82-0.98], p = 0.019) during maintenance therapy from 3 weeks to 2 years.

Conclusions: While lower baseline A1c and greater reduction in central adiposity predicted A1c <6.0% at 2 years as anticipated, the emergence of greater reduction in ALT as a concomitant determinant highlights the role of the liver in the achievement of sustained glycaemic normalisation.