Midlife muscle strength tied to diabetes in Singaporean women

Greater upper and lower body muscle strength appears to be associated with a lower likelihood of diabetes among midlife women in Singapore, as reported in a recent study.

The odds of having diabetes were almost 60-percent higher among women with weak vs normal handgrip strength (≥18 vs <18 kg on a dynamometer; adjusted odds ratio [aOR], 1.59, 95 percent confidence interval [CI], 1.03–2.44), independent of adiposity and muscle mass. [Int J Environ Res Public Health 2022;19:13654]

A similar pattern of association was noted for poor vs good performance on the prolonged 5-repetition chair stand (RCS) test (≥12 vs <12 s; aOR, 1.59, 95 percent CI, 1.09–2.30), although this was attenuated upon further adjustment for adiposity and muscle mass.

When handgrip strength and RCS test performance were combined in a muscle strength index (MSI), poor MSI was more common among women with diabetes, while an intermediate and normal MSI was more common among those without diabetes. The poor MSI category (ie, weak HGS and prolonged RCS) was associated with a more than twofold higher likelihood of diabetes (aOR, 2.37, 95 percent confidence interval [CI], 1.40–4.03). This association persisted even after sequential adjustment for the full set of covariates, including adiposity and muscle mass.

“Our findings [a]re consistent with that of a recent meta-analysis demonstrating a 27-percent reduced risk for diabetes in a comparison of the top vs bottom thirds of handgrip strength levels… Thresholds of normalized grip strength have been proposed as useful screening tools for diabetes risk in otherwise healthy adults,” according to the investigators. [Diabetes Metab Res Rev 2021;37:e3365; Diabetologia 2019;62:1129-1142; Am J Prev Med 2020;58:757-765]

They acknowledged that grip strength “might not be entirely representative of whole-body strength,” given that factors such as obesity could differentially affect the muscle strength in the upper and lower extremities.

With regard to the RCS test, the investigators said that to the extent of their knowledge, the tool has not been reported to be associated with diabetes among healthy individuals. On the other hand, the Timed Up and Go test—a similar test that assesses fall risk and involves rising from a chair, walking for 3 m, walking back to the chair, and sitting back down—has been linked to a higher risk of diabetes in older Chinese women. This association, according to the investigators, may be related to ageing-associated phenotypes such as muscle weakness and cognitive impairment. [PLoS ONE 2014;9:e115883]

“Our findings confirm the results of a recent study in older Chinese subjects, which observed that a composite score incorporating both relative grip strength and the Timed Up and Go test was associated with incident diabetes,” they added. [Aging 2021;13:18376-18391]

The present analysis included 1,170 women (average age 56.3 years, 83.5 percent Chinese, 71.7 percent postmenopausal), among whom 259 (22.1 percent) had weak HGS (<18 kg) while 519 (44.4 percent) performed poorly on the RCS test (≥12 s). MSI was poor (HGS <18 kg and RCS test ≥12 s) in 153 (13.1 percent) women, intermediate MSI (HGS <18 kg only or RCS test ≥12 s only) in 472 (40.3 percent), and normal (HGS ≥18 kg and RCS test <12 s) in 545 (46.6 percent).

More than half (53.7 percent) of the women were overweight or obese, and 12.1 percent had diabetes. Of note, the diabetic group tended to have greater muscle mass than the nondiabetic group (68.8 percent vs 45.5 percent).

“Future studies of muscle strength as a risk factor for diabetes should account for the muscle strength of both the upper and lower body,” according to the investigators, who also called for additional studies to establish the causal relationship and direction between muscle strength and diabetes.