Ethnic Disparities in Glycemic Control Increase in United States

Ethnic disparities in glycemic control increased in adults with diabetes in the United States who received insulin, with Mexican Americans and non-Hispanic Black Americans the most affected, according to a new study published today in JAMA Network Open.

Insulin is used as a last-line therapy for patients with type 2 diabetes but little is known about glycemic control in patients using insulin. This study aimed to examine national trends of glycemic control and severe hyperglycemia in patients with diabetes who use insulin.

The researchers used the National Health and Nutrition Examination Survey (NHANES), specifically the NHANES III conducted from 1988 to 1994 and the continuous NHANES with data from 1999 to 2020, and the study included nonpregnant patients who aged 20 years and older with a diagnosis of diabetes from a doctor or health professional.

Glycated hemoglobin (HbA_1C) level was measured with a high-performance liquid chromatography, with severe hyperglycemia defined as a level of HbA_1C that was greater than 10%. Self-reported age, race and ethnicity, health insurance status, education level, health care utilization, family income, age at diabetes diagnosis, and gender were used for all participants.

There were 2482 participants in this study; their mean (SD) age was 59.8 (0.4) years and 51.3% were male patients. There were 65.2% non-Hispanic White participants, 17.9% non-Hispanic Black participants, and 7.0% Mexican American participants.

There was an increase in the mean duration of diabetes from 1988-1994 to 2013-2020: 12.9 (95% CI, 11.5-14.3) to 17.8 (95% CI, 16.8-18.8) years. Increases were also seen in the proportion of individuals who were Mexican Americans, from 4.2% (95% CI, 3.1%-5.7%) to 9.0% (95% CI, 6.5%-12.3%); the proportion of participants covered by public or other insurance, from 23.8% (95% CI, 17.3%-31.9%) to 42.0% (95% CI, 37.2%-47.1%); and those with a body mass index that was higher than 30, from 38.3% (95% CI, 31.3%-45.8%) to 66.6% (95% CI, 61.1%-71.7%).

The researchers did not find a significant change in adults who achieved glycemic control or who had severe hyperglycemia when they were using insulin. However, race and ethnicity were found to influence glycemic control. Mexican American adults had a significant decrease in glycemic control over time: 25.1% (95% CI, 17.2%-35.1%) in 1988-1994 to 9.9% (95% CI, 5.4%-17.4%) in 2013-2020. Higher levels of glycemic control were found in non-Hispanic White individuals (32.9%; 95% CI, 24.3%-42.8%) and college-educated adults (33.9%; 95% CI, 23.3%-46.5%) compared with their counterparts.

Mexican Americans (23.9%; 95% CI, 13.6%-38.7%) and non-Hispanic Black Americans (22.7%; 95% CI, 17.4%-29.0%) had a higher prevalence of severe hyperglycemia compared with non-Hispanic White participants (9.1%; 95% CI, 6.0%-13.7%).

Mexican American participants were also found to be less likely to achieve glycemic control (odds ratio [OR], 0.45; 95% CI, 0.30-0.68) vs non-Hispanic White participants. Mexican Americans (OR, 2.29; 95% CI, 1.32-3.98) and non-Hispanic Black participants (OR, 2.48; 95% CI, 1.71-3.61) were more likely to have severe hyperglycemia. Participants 65 years and older were more likely to have glycemic control and less likely to have severe hyperglycemia compared with younger groups.

There were some limitations to this study. Causes of these results could not be found due to the cross-sectional nature of the study, and insulin type and use were self-reported and did not include adherence. Also, noninstutionalized adults were the only ones sampled in the NHANES, which could have eliminated a segment of the population with diabetes.

The researchers concluded that “despite advancements in insulin formulations and diabetes management strategies, glycemic control and severe hyperglecemia among adults using insulin did not improve in the general US adult population with diabetes.”

Reference

Venkatraman S, Echouffo-Tcheugui JB, Selvin E, Fang M. Trends and disparities in glycemic control and severe hyperglycemia among US adults with diabetes using insulin, 1988-2020. JAMA Netw Open. 2022;5(12):e2247656. doi:10.1001/jamanetworkopen.2022.47656