Primary care screening for individuals with impaired glucose metabolism with focus on impaired glucose tolerance

Haemoglobin A1c as a screening tool for type 2 diabetes and prediabetes in populations of Swedish and Middle-East ancestry

AIMS

To explore and compare sensitivity and specificity for HbA1c ≥48mmol/mol as a predictor for type 2 diabetes mellitus (T2DM) in two populations with different ethnicity and to examine the predictive value of two levels of HbA1c (≥42mmol/mol, ≥39mmol/mol) for prediabetes in these populations.

METHODS

Four cohorts were examined with an oral glucose tolerance test. (1) The MEDIM Study (n=1991 individuals of Swedish and Iraqi ancestry); (2) The Skaraborg Project (n=1327 individuals of Swedish ancestry); (3) The 4-D study (n=424 individuals of Swedish, Iraqi and Turkish ancestry); (4) The Flemingsberg study (n=212 participants of Turkish ancestry).

RESULTS

HbA1c ≥48mmol/mol had a sensitivity for T2DM of 31% and 25% respectively in individuals of Middle-East and Swedish ancestry. The positive and negative predictive value was high in both populations (70.3, 96.4 and 96.2, 97.6 respectively). Using HbA1c ≥42mmol/mol and ≥39mmol/mol as a predictor for prediabetes gave a sensitivity of 17% and 36% in individuals of Middle-East and 15% and 34% in individuals of Swedish ancestry.

CONCLUSIONS

Even if HbA1c ≥48mmol/mol is a valuable diagnostic tool, it is a blunt and insensitive tool for screening and would exclude most people with T2DM, independent of ancestry and age. HbA1c is an inefficient way to detect individuals with prediabetes.

A lifestyle intervention in primary care prevents deterioration of insulin resistance in patients with impaired glucose tolerance: A randomised controlled trial

Aims: We hypothesised that the expected increase in insulin resistance over three years’ time in individuals with impaired glucose tolerance (IGT) and/or impaired fasting glucose could be attenuated by an intervention with focus on physical activity in ordinary primary care. Methods: We conducted a randomised controlled trial with 96 participants over three years. Examination of the participants included anthropometric measures, blood pressure, body weight and height, blood samples, an oral glucose tolerance test, and questionnaires about diet and lifestyle. The study subjects were randomised to either an intense intervention with information, group sessions, referral to physical activity and a step-counter ( n = 31), a less intense intervention without the group sessions ( n = 35), or care as usual group (CAUG) ( n = 30). Differences between the groups were analysed with general linear models adjusted for age, gender, baseline values and time in the intervention. Results: Individual insulin resistance increased in the CAUG. Due to having a similar effect, we combined the two intervention groups into a combined intervention group (CIG; n = 66) in the analyses. In individuals with IGT, the increase in the homeostatic model assessment-insulin resistance differed significantly between those in the CAUG and the CIG (Δ = 0.8; CI: 0.1–1.6; p = 0.034). Likewise, diastolic blood pressure decreased more in the CIG than in the CAUG (Δ = 5.1; CI: 0.1–10.0; p = 0.047). A total of 17 individuals developed Type 2 diabetes, 23% were in the CIG and 33% in the CAUG; so there was a 32% reduced risk in the intervention group. Conclusions: A lifestyle intervention focused on physical activity is feasible in ordinary primary care and prevents deterioration in insulin sensitivity in individuals with IGT over a three-year period.

IDENTIFYING PROBABLE DIABETES MELLITUS AMONG HISPANICS/LATINOS FROM FOUR U.S. CITIES: FINDINGS FROM THE HISPANIC COMMUNITY HEALTH STUDY/STUDY OF LATINOS

OBJECTIVE

The aim of this study was to compare the ability of American Diabetes Association (ADA) diagnostic criteria to identify U.S. Hispanics/Latinos from diverse heritage groups with probable diabetes mellitus and assess cardiovascular risk factor correlates of those criteria.

METHODS

Cross-sectional analysis of data from 15,507 adults from 6 Hispanic/Latino heritage groups, enrolled in the Hispanic Community Health Study/Study of Latinos. The prevalence of probable diabetes mellitus was estimated using individual or combinations of ADA-defined cut points. The sensitivity and specificity of these criteria at identifying diabetes mellitus from ADA-defined prediabetes and normoglycemia were evaluated. Prevalence ratios of hypertension, abnormal lipids, and elevated urinary albumin-creatinine ratio for unrecognized diabetes mellitus-versus prediabetes and normoglycemia-were calculated.

RESULTS

Among Hispanics/Latinos (mean age, 43 years) with diabetes mellitus, 39.4% met laboratory test criteria for probable diabetes, and the prevalence varied by heritage group. Using the oral glucose tolerance test as the gold standard, the sensitivity of fasting plasma glucose (FPG) and hemoglobin A1c-alone or in combination-was low (18, 23, and 33%, respectively) at identifying probable diabetes mellitus. Individuals who met any criterion for probable diabetes mellitus had significantly higher (P<.05) prevalence of most cardiovascular risk factors than those with normoglycemia or prediabetes, and this association was not modified by Hispanic/Latino heritage group.

CONCLUSION

FPG and hemoglobin A1c are not sensitive (but are highly specific) at detecting probable diabetes mellitus among Hispanics/Latinos, independent of heritage group. Assessing cardiovascular risk factors at diagnosis might prompt multitarget interventions and reduce health complications in this young population.

ABBREVIATIONS

2hPG = 2-hour post-glucose load plasma glucose ADA = American Diabetes Association BMI = body mass index CV = cardiovascular FPG = fasting plasma glucose HbA1c = hemoglobin A1c HCHS/SOL = Hispanic Community Health Study/Study of Latinos HDL-C = high-density-lipoprotein cholesterol NGT = normal glucose tolerance NHANES = National Health and Nutrition Examination Survey OGTT = oral glucose tolerance test TG = triglyceride UACR = urine albumin-creatinine ratio.