Gestational diabetes mellitus (GDM), a common complication during pregnancy, is defined as diabetes first diagnosed between approximately 24 and 28 weeks of gestation and is caused by hormonal and physiological changes during pregnancy [1,2]. The global prevalence of GDM is estimated at about 14% of pregnant women worldwide [3].

Women with GDM face increased risks to both maternal and fetal health, including a higher likelihood of fetal malformations, premature birth, infections, elevated fetal mortality, and a greater probability of cesarean section [4,5]. Even after delivery, women with GDM are at higher risk of developing type 2 diabetes, cardiovascular disease, and hypertension compared with healthy pregnant women [6,7]. Therefore, proper blood glucose management is essential to protect both maternal and fetal health and to minimize complications [8].

For women with GDM, lifestyle interventions such as blood glucose self-monitoring, dietary management, and exercise represent the first-line treatment [8]. These strategies alone successfully manage 70%–85% of cases [9]. The primary goals of exercise in GDM are to maintain normal blood glucose levels and manage weight, thereby reducing complications [2,8]. Some earlier studies suggested an association between exercise and increased risk of preterm labor, attributed to catecholamine release and reduced placental circulation [10,11]. However, other studies have shown that exercise during pregnancy does not raise the risk of preterm labor or cesarean section. On the contrary, exercise can prevent and control obesity, gestational hypertension, premature birth, and GDM itself [12,13].

Except for obstetric problems, current guidelines recommend that women with GDM perform moderate-intensity aerobic exercise five times per week for 30 minutes per session, totaling 150 minutes weekly. Alternatively, simple activities such as walking for 10–15 minutes after meals are advised [8]. Moderate-intensity resistance exercise for 1 hour, 2–3 times weekly, is also recommended [14]. Despite these guidelines, supporting evidence remains limited. Variability in intervention characteristics and inconsistent findings regarding their effects on glycemic control contribute to this gap [15,16], underscoring the need for additional empirical clarity.

Studies have reported inconsistent outcomes of exercise on glycemic control in GDM [17]. For example, moderate-intensity aerobic exercise showed no significant effect [18], while low-intensity activity [19] and high-intensity interval training were effective in women without complications [20]. Resistance exercise demonstrated greater benefits than aerobic exercise in one study [7], but generalizability remains limited.

Most earlier reviews have concentrated on the prevention of GDM in otherwise healthy pregnant women [21,22]. Only a few have evaluated exercise effects in women already diagnosed with GDM, and their findings have been inconsistent. One meta-analysis reported significant benefits in women with GDM or at high risk [15], whereas another found no significant effects of supervised exercise programs lasting less than 4 weeks [16]. These discrepancies may stem from differences in intervention characteristics (e.g., type, duration, and intensity), participant factors (e.g., age, gestational age), and methodological variations such as glucose measurement approaches (plasma vs. whole blood). Thus, it is essential to clarify the effects of exercise interventions on glycemic control in women with GDM by analyzing outcomes according to intervention characteristics within clearly defined inclusion criteria.

To address this, the present study aimed to synthesize the most up-to-date evidence to identify the independent effects of exercise and determine optimal intervention features. Through a systematic literature review and meta-analysis, we aim to provide integrated insights for developing safe and effective exercise programs for women with GDM.

For the 12 studies included in the meta-analysis (excluding [26,35,38]), 11 [25,27-32,34,36,37,39] provided sufficient data for effect size analysis of FBS, and 10 [25,27-32,34,36,37] for PPG2hr. Additionally, five studies [30-33,39] enabled effect size analysis of HbA1c. When reviewing intervention characteristics, all studies with available data reported exercise intensity as moderate and frequency as more than three times per week. Accordingly, subgroup analyses were performed for exercise duration, session time, and type.

The results of this meta-analysis of 12 studies demonstrated that FBS, PPG2hr, and HbA1c levels were significantly lower in the exercise intervention group compared with the control group (–0.47 mmol/L, –0.62 mmol/L, and –0.39%, respectively). The glucose control targets for GDM are generally 5.3, 7.8, and 6.7 mmol/L for FBS, PPG1hr, and PPG2hr, respectively [47]. Although evidence on the minimum clinically important difference in glycemic control for women with GDM is still limited [48], previous research has indicated that even a 1 mmol/L change in blood glucose can alter the risk of adverse pregnancy outcomes [49] and is associated with differences in the incidence of cardiovascular disease [50]. Thus, the observed significant reductions in both FBS and PPG2hr in this study can be considered clinically meaningful.

In this meta-analysis, HbA1c was also significantly lower in the exercise intervention group compared with the control group (–0.39%), suggesting that exercise contributes to reducing the risk of GDM-related complications. However, in most included studies, HbA1c levels in both groups were already within the recommended GDM target range of 5.5%–6.5% [51]. This likely reflects the effects of routine care—such as dietary counseling and glucose monitoring—commonly provided to women with GDM. Under these circumstances, while the additional effect of exercise is statistically significant, the clinical interpretation of HbA1c reduction alone requires caution. HbA1c may have limited sensitivity as an outcome measure for exercise interventions in GDM [3]. Since HbA1c reflects average blood glucose over the prior 1–2 months, the duration of exercise, timing of measurement, and attainment of individualized glucose goals should all be considered when evaluating intervention effects.

Nevertheless, prior studies indicate that even small increases in HbA1c (5.1%–5.4% or ≥5.5% vs. ≤5.0%) are significantly associated with increased risks of cesarean delivery, gestational hypertension, and macrosomia [52]. This suggests that modest reductions in HbA1c achieved through exercise may hold clinical significance in GDM management. Therefore, although the absolute reductions observed may appear small, exercise-based glycemic control can help prevent adverse maternal and neonatal outcomes such as macrosomia, as well as long-term metabolic complications.

In the subgroup analyses, the effects of exercise duration showed some variability. For FBS, modest but significant reductions were observed with 1–7 weeks of exercise, while the 8–14 weeks group showed larger but statistically nonsignificant reductions. In contrast, PPG2hr declined more consistently with longer exercise durations, and HbA1c showed significant improvement with 8–14 weeks of intervention. Considering that women with GDM are generally advised to exercise after meals [53], it is reasonable that reductions in PPG2hr were greater than in FBS. Despite the limitations of HbA1c as an outcome measure, the observed decreases suggest that exercise lasting more than 8 weeks may yield greater benefits for glycemic control [25]. Still, due to limited data, further rigorously designed trials are needed to substantiate these findings.

Analysis by session length revealed that both FBS and PPG2hr levels were lower when exercise was performed for 15–29 minutes compared with 30–60 minutes. Women in the shorter-duration group generally exercised more frequently, suggesting that higher frequency may compensate for reduced duration, resulting in superior glycemic outcomes. This aligns with evidence from type 2 diabetes research [53], which found that shorter, more frequent exercise sessions were more effective for glucose regulation. A prior review also noted that even low-intensity exercise, if maintained consistently, can improve insulin resistance [54]. These findings provide scientific support for current recommendations [14] encouraging women with GDM to perform short, frequent bouts of postprandial exercise—such as 10–15 minutes after meals—rather than focusing solely on accumulating 150 minutes per week in sessions lasting ≥30 minutes. The present findings therefore support the recommendation that women with GDM engage in approximately 15 minutes of exercise after meals, 7–10 times per week, rather than limiting activity to three or more longer sessions (30 minutes or more) weekly.

Analysis of the exercise intervention data revealed that FBS improved significantly only with aerobic exercise, while PPG2hr improved significantly regardless of exercise type (aerobic or resistance). Aerobic exercise enhances insulin sensitivity to lower blood glucose levels, whereas resistance exercise increases muscle mass, thereby improving impaired glucose tolerance and glycogen storage capacity [55,56]. Engaging both metabolic pathways simultaneously may be physiologically more beneficial than relying on a single type of exercise [14].

Interestingly, the subgroup categorized as “not reported” consistently showed greater reductions in FBS, PPG2hr, and HbA1c across intervention duration, timing, and type. Although the intervention details in these studies were not explicitly reported, most described individualized exercise programs maintained from enrollment until delivery. The extended duration and tailored nature of these interventions may have contributed to the observed effects. However, because specific program details were unclear and potential confounding factors cannot be ruled out, these findings must be interpreted cautiously in clinical settings. Further rigorous randomized controlled trials (RCTs) are needed to determine whether the observed benefits in this subgroup were attributable to exercise duration, intensity, or individualization.

A key strength of this study is the clearly defined population, consisting solely of women diagnosed with GDM, distinct from those merely at high risk. Compared with prior systematic reviews, this study offers more precise insights by conducting subgroup analyses of detailed exercise parameters—such as timing, duration, and type. These analyses refine individualized recommendations for exercise-based glycemic control in GDM, a topic not fully addressed in earlier reviews. This clarity allowed a more precise identification of the magnitude of glycemic control effects. In addition, a sub-analysis was conducted according to the content of the exercise program and its effects, which enabled the proposal of targeted exercise strategies for GDM management. Moreover, analyzing all three blood glucose indicators (FBS, PPG2hr, and HbA1c) in relation to exercise content may help establish more specific goals for future exercise programs.

Although subgroup analyses were conducted by exercise type, duration, and timing, variables such as exercise intensity, frequency, and measurement methods could not be analyzed because of incomplete and inconsistent reporting across studies. Another limitation was that exercise intensity and frequency were reported in only a few studies, and the reporting formats varied considerably, making direct comparisons difficult. With respect to heterogeneity, overall I² was high for FBS (96%) and PPG2hr (92%) and moderate for HbA1c (72%). By duration (<8 weeks, ≥8 weeks, not reported), I² values were 87%, 97%, and 80% for FBS, and 85%, 0%, and 90% for PPG2hr. By exercise time (15–29 minutes, 30–60 minutes, not reported), I² values were 89%, 0%, and 74% for FBS, and 11%, 4%, and 74% for PPG2hr. By exercise type (aerobic, resistance, not reported), I² values were 90%, 41%, and 96% for FBS, and 83%, 0%, and 77% for PPG2hr. Despite subgrouping by these intervention characteristics, substantial heterogeneity persisted in several subgroups. In particular, the aerobic subgroup showed high heterogeneity, likely reflecting the inclusion of varied exercise modes and intensities under the single category of “aerobic,” thereby reducing homogeneity. Likewise, the “not reported” or “other” subgroups could not be clearly classified, limiting analytical precision. These factors may explain the persistence of heterogeneity. Although some reduction in heterogeneity was observed after subgrouping by exercise timing, considerable variability remained overall. This suggests that unmeasured or unreported factors—such as measurement methods, cultural context, or baseline participant characteristics—may have contributed to heterogeneity. Consequently, these findings should be interpreted with caution. While the funnel plot suggested possible heterogeneity, the Egger test indicated that publication bias was not statistically significant (Figure 5). To address these issues, further RCTs with clear reporting of exercise intensity, frequency, and measurement methods are needed to clarify sources of heterogeneity and more accurately evaluate the effects of exercise interventions. In addition, studies conducted across diverse cultural contexts are warranted.

Accordingly, more rigorously designed experimental studies, together with updated systematic reviews and meta-analyses, are required. The present study supports exercise intervention as an effective strategy for glycemic control in women with GDM. In particular, exercising for approximately 15 minutes after meals, 7–10 times per week, may be more beneficial than the general recommendation of at least 30 minutes of exercise three times per week. These results highlight the potential value of individualized, frequent, and low-burden exercise strategies tailored specifically for women with GDM.

In conclusion, this study found exercise intervention to be more effective when the session length was ≤30 minutes and the intervention period exceeded 8 weeks. Moreover, personalized exercise programs tailored to individual needs may yield additional benefits. Overall, the findings strongly suggest that exercise interventions are effective for improving blood glucose control in GDM, particularly when implemented as short, frequent sessions scheduled after meals.