Patients with impaired glucose tolerance show poor response to lifestyle changes

A study of Thai patients with impaired glucose tolerance (IGT) has found only a slight reduction in weight among its participants, highlighting the need for more intensive efforts with structured lifestyle programs to prevent diabetes.

Additionally, the use of metformin should be considered if patients are unable or unwilling to lose weight with lifestyle changes, according to the researchers, led by Waralee Chatchomchuan, who presented the study at the 82nd Scientific Sessions of the American Diabetes Association (ADA 2022).

“Even though lifestyle modifications and pharmacological interventions have been shown to be effective in patients who have IGT, the patients’ responses to lifestyle changes after receiving the diagnosis of IGT in Thai patients are lacking.

Chatchomchuan and colleagues conducted a 5-year retrospective study of newly diagnosed Thai patients with IGT in Theptarin Hospital in Bangkok, Thailand, from 2016 to 2020 to assess the weight changes following diagnosis and explain the patterns of metformin use in this cohort. They also determined the prevalence and characteristics of metformin prescription among participants.

A total of 266 patients with IGT (mean age 51.8 years, 63.9 percent female, mean body weight 69.8 kg, mean body mass index [BMI] 26.5 kg/m²) were included in the analysis. About one in five of these patients use metformin, with a prevalence rate of 21.1 percent. [ADA 2022, abstract 645-P]

The mean weight change was only ‒1.0 kg during follow-up. Patients receiving metformin had a significant weight reduction relative to controls (mean weight change ‒2.2 vs ‒0.7 kg; p=0.006). In addition, nearly one in four patients (26.8 percent) who was prescribed metformin was successful in reducing >5 percent weight.

Metformin use was more likely to be prescribed in patients who were older (age ≥60 years), had BMI ≥35 kg/m², concomitant statin usage, combined impaired fasting glucose and IGT, and A1c ≥6.0 percent.

Insulin sensitivity

A 2001 study showed that use of metformin increased insulin sensitivity in patients with IGT, driven by the reversal of the glucose fatty acid cycle. Metformin treatment led to a 20-percent improvement in insulin-stimulated glucose metabolism relative to placebo (p=0.01). [Diabet Med 2001;18:578-83]

“These changes were associated with a minimal improvement in glucose tolerance, which was maintained after 12 months,” the authors said.

In a more recent study, Ulrike Hostalek and colleagues reported that prediabetic patients could benefit from a combination of lifestyle and pharmacologic interventions to prevent or delay the onset of type 2 diabetes. Their results confirmed the benefits of metformin in diabetes prevention, together with counselling, to achieve a healthier lifestyle. [Drugs 2015;75:1071-1094]

“Metformin enhances the action of insulin in liver and skeletal muscle, and its efficacy for delaying or preventing the onset of diabetes has been proven in large, well-designed, randomized trials, such as the Diabetes Prevention Program and other studies,” the investigators said. “Decades of clinical use have demonstrated that metformin is generally well-tolerated and safe.”