Background Formula diets can improve glycemic control or can even induce remission in type 2 diabetes. We hypothesized that especially an individualized intense meal replacement by a low-carbohydrate formula diet with accompanied self-monitoring of blood glucose (SMBG) contributes to long-term improvements in HbA1c, weight, and cardiometabolic risk factors in poorly controlled type 2 diabetes. Methods Type 2 diabetes patients were randomized into either a moderate group (M-group) with two meal replacements/day (n = 160) or a stringent group (S-group) with three meal replacements/day (n = 149) during the first week of intervention (1300⁻1500 kcal/day). Subsequently, both groups reintroduced a low-carbohydrate lunch based on individual adaption due to SMBG in weeks 2⁻4. After week 4, breakfast was reintroduced until week 12. During the follow-up period, all of the participants were asked to continue replacing one meal per day until the 52-weeks follow-up. Additionally, an observational control group (n = 100) remained in routine care. Parameters were compared at baseline, after 12 and 52 weeks within and between all of the groups. Results 321 participants (83%) completed the acute meal replacement phase after 12 weeks and 279 participants (72%) the whole intervention after 52 weeks. Both intervention groups achieved improvements in HbA1c, fasting blood glucose, blood pressure, and weight (all p < 0.001) within 12 weeks. However, these results were not significantly different between both of the intervention groups. The estimated treatment difference in HbA1c reduction was (mean (95% confidence interval [CI]) -0.10% with 95% CI [-0.40; 0.21] also (p > 0.05) (S-group vs. M-group) not statistically different after 12 weeks. However, only the S-group showed a clinically relevant improvement in HbA1c of -0.81% [-1.06; -0.55] (p < 0.001) after 52 weeks of follow-up, whereas HbA1c was not statistically different between the M- and control group. Conclusion Individualized meal replacement with SMBG demonstrated beneficial effects on HbA1c and cardiometabolic parameters in type 2 diabetes. Furthermore, the initiation of a weight loss program with one week of full meal replacement (three meals per day) resulted in a clinically relevant long-term HbA1c reduction, as compared to an observational control group that had standard care.
Keywords: HbA1c; formula diet; low-carbohydrate diet; type 2 diabetes; weight loss.