Daily metformin prevents type 2 diabetes among patients with metabolic syndrome
Key takeaways:
- Cumulative incidence of noncommunicable diseases was lowest among those who received metformin plus the Mediterranean diet.
- Metformin significantly reduced type 2 diabetes in patients with metabolic syndrome.
Participants with metabolic syndrome who received 1,700 mg metformin daily with or without a Mediterranean diet intervention had reduced incidence of diabetes compared with placebo, according to findings published in Diabetes Care.
Metabolic syndrome is a significant risk factor for multiple noncommunicable diseases (NCDs), including type 2 diabetes, cardiovascular diseases and cancer. Previous studies have shown that the Mediterranean diet can lower the prevalence of metabolic syndrome and potentially revert it.
Further, researchers have recently uncovered many additional properties of metformin that may have a potential protective effect on multiple disorders, Patrizia Pasanisi, MD, director of nutritional and metabolomic research at the Fondazione IRCCS Istituto Nazionale dei Tumori in Milan, and colleagues wrote. However, additional research concerning its ability to prevent NCDs is needed.
Researchers conducted the Metformin and Dietary Restriction to Prevent Age-Related Morbid Events in People With Metabolic Syndrome (MeMeMe) trial to investigate how daily metformin with or without Mediterranean diet adherence would impact the cumulative incidence of major NCDs among people with metabolic syndrome.
The randomized controlled study included 1,442 participants (mean age, 62.5 years) who were assigned to one of four treatment arms: 1,700 mg daily oral metformin and Mediterranean diet intervention (n = 358); Mediterranean diet intervention and placebo (n = 368); metformin alone (n = 373); and placebo (n = 343).
Average follow-up was 3 years, with the participants followed for a maximum of 5 years.
The cumulative incidence of NCDs served as the study’s primary outcome; researchers also measured the incidence of type 2 diabetes and the changing prevalence of metabolic syndrome as secondary outcomes.
Additionally, they measured adherence to Mediterranean diet through a 24-hour food frequency diary, which was scored based on compliance with food recommendations, and they collected an annual blood sample to diagnosis diabetes.
Pasanisi and colleagues found that, after 1 year of intervention, the metformin alone and metformin plus Mediterranean diet intervention groups had significantly reduced body weight, BMI and glycemia compared with either placebo group.
The incidence of CVDs and cancer did not differ across the groups, with cancer mortalities only occurring in the groups treated with metformin.
Further, the researchers found that the cumulative incidence of the NCDs studied was significantly lower in the metformin alone (6.9 cases per 100 person-years) and metformin plus Mediterranean diet intervention (6.7 cases per 100 person-years) groups compared with the placebo plus Mediterranean diet (13.3 cases per 100 person-years) and placebo alone (11.3 cases per 100 person-years) groups.
Compared with the placebo-alone group, the adjusted HR for NCDs appeared lowest for the metformin plus Mediterranean diet intervention group (aHR = 0.48; 95% CI, 0.29-0.82) and the metformin alone group (aHR = 0.51; 95% CI, 0.3-0.86), with no significant effect observed in the placebo plus Mediterranean diet intervention group (aHR = 1.09; 95% CI, 0.7-1.7). The researchers noted these results persisted after adjustments for age, baseline BMI and sex.
However, these differences were largely due to the significant reduction of type 2 diabetes in the groups who received metformin, the researchers wrote. They identified 48 cases of type 2 diabetes in the placebo groups vs. seven cases in the metformin groups.
Compared with the placebo group, they found that type 2 diabetes incidence was 80% lower (HR = 0.2; 95% CI, 0.1-0.55) in the metformin group and 92% lower (HR = 0.08; 95% CI, 0.02- 0.35) in the metformin plus Mediterranean diet group. Adjustments for age, baseline BMI and sex did not change these results.
The researchers noted several limitations to the study, including the lack of glucose tolerance testing at baseline and follow-up, and the potential failure to diagnose all diabetes cases.
“[Daily metformin] is effective in the prevention of diabetes, but not other NCDs, in people selected on the basis of metabolic syndrome,” Pasanisi and colleagues wrote.
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