Reduction in urinary albumin excretion with a moderate low-carbohydrate diet in patients with type 2 diabetes: a 12-month intervention

Dysregulation of miR-638 in diabetic nephropathy and its role in inflammatory response

BACKGROUND

MicroRNA (miRNA) can be used as a biomarker for the early diagnosis of diabetic nephropathy (DN). The purpose of this study was to evaluate the diagnostic value of miR-638 in DN and to analyse its regulatory effect on inflammation.

METHODS

This retrospective study involved 98 subjects, including non-diabetic healthy controls (n = 30), patients with type 2 diabetes (T2DM, n = 36) without complications and patients with DN (n = 32). After the anthropometric and biochemical evaluation, serum miR-638 levels were assessed by real-time reverse transcription-polymerase chain reaction (qRT-PCR). The levels of inflammatory cytokines (interleukin [IL]-1β, IL-6, and tumor necrosis factor-alpha [TNF-α]) were detected using enzyme-linked immunosorbent assay. The Spearman correlations were used to analyze the correlation between miR-638 and urinary albumin excretion (UAE), estimated glomerular filtration rate (eGFR), and inflammatory factors. Furthermore, the receiver operating characteristic (ROC) curve was used to measure the diagnostic value of miR-638 in DN. Human mesangial cells (HMCs) were treated with normal glucose (NG, 5.5 mM glucose), high glucose (HG, 30 mM glucose), or high osmotic pressure solution (HO, 5.5 mM glucose + 24.5 mM mannitol) in vitro to simulate the hyperglycamic state in vivo. Subsequently, the HMCs were transfected with miR-638 mimics to regulate the level of miR-638 in the cells and detect its regulation on cell inflammation and proliferation.

RESULTS

Compared with healthy controls and patients with T2DM, serum miR-638 in patients with DN was significantly lower. The reduced miR-638 expression has a significant diagnostic value, which can significantly distinguish patients with DN from healthy controls or patients with T2DM. Inflammatory factors were significantly upregulated in patients with DN and negatively correlated with miR-638 levels. In addition, miR-638 was negatively correlated with UAE and positively correlated with eGFR. HG decreased the level of miR-638 and promoted the expression of inflammatory factors and proliferation in HMCs. However, miR-638 mimic significantly decreased the levels of inflammatory factors and inhibited the proliferative ability induced by HG.

CONCLUSIONS

Serum miR-638 expression was low in DN and can be a potentially valuable biomarker for DN. This miRNA seems to influence inflammatory responses and participate in the progression of DN by regulating proliferation.

Dietary intake in type 1 diabetes at different stages of diabetic kidney disease

AIM

Diet plays an important role in the kidney health of individuals with type 1 diabetes. However, not much is known about dietary practices at different stages of diabetic nephropathy. We aimed at investigating food intake, dietary patterns, and nutrient intakes in individuals with type 1 diabetes differing in renal status.

METHODS

Data were available from 1874 individuals with type 1 diabetes (45% men, age 48 ± 13 years). Diet was assessed at the levels of food items and diet patterns (diet questionnaire), and energy and nutrient intakes (food record). Six groups were formed based on the eGFR or dialysis and transplantation status.

RESULTS

Reductions in liquid-milk product and salt consumption, and increase in special diet adherence were observed at the early stages of eGFR decline. Reduced coffee consumption was observed after eGFR was <30 ml/min/1.73 m². With advancing kidney failure, rye bread consumption decreased, but that of wheat bread increased. Compared to those with intact kidney function (the index group), the Fish and vegetable diet pattern scores were higher in individuals with mildly-to-severely decreased eGFR. Instead, the Sweet pattern scores were lower than in the index group in all other groups. Energy intake was lower in all groups compared to those with intact kidney function. Advancing kidney failure was associated with reductions in protein intake per body weight, and in the intakes of sodium, potassium, calcium, and phosphorus.

CONCLUSIONS

Differences in the dietary intake are seen already at the early stages of kidney function decline.

Effect of combined use of a low-carbohydrate, high-protein diet with omega-3 polyunsaturated fatty acid supplementation on glycemic control in newly diagnosed type 2 diabetes: a randomized, double-blind, parallel-controlled trial

Background

The combined effect of a low-carbohydrate, high-protein (LCHP) diet and omega-3 (n-3) polyunsaturated fatty acid (PUFA) supplementation on patients with type 2 diabetes (T2D) is not known.

Objective

The aim of this study was to evaluate the effect of an LCHP diet combined with ω-3 (LCHP+ω-3) on glycemic control in patients with T2D.

Design

In this randomized, double-blind, parallel-controlled trial, 122 newly diagnosed participants with T2D were randomly assigned to receive a high-carbohydrate, low-protein diet with low ω-3 PUFAs [control (CON)], an LCHP, ω-3, or LCHP+ω-3 diet for 12 wk. The ratio of carbohydrate to protein was 42:28 in the LCHP and LCHP+ω-3 diet and 54:17 in the CON and ω-3 diet. The participants were given 6 g fish oil/d (containing 3.65 g docosahexaenoic acid, eicosapentaenoic acid, and docosapentaenoic acid/d) in the ω-3 and LCHP+ω-3 diet groups or 6 g corn oil/d (placebo) in the CON and LCHP diet groups.

Results

Compared with the CON diet group, greater decreases in glycated hemoglobin (HbA1c) and fasting glucose were observed in all of the other 3 diet groups at 12 wk. Of note, HbA1c reduction in the LCHP+ω-3 diet group (-0.51%; 95% CI: -0.64%, -0.37%) was greater than that in the LCHP (P = 0.03) and ω-3 (P = 0.01) diet groups at 12 wk. In terms of fasting glucose, only the LCHP+ω-3 diet group showed a significant decrease at 4 wk (P = 0.03 compared with CON). Moreover, the reduction in fasting glucose in the LCHP+ω-3 diet group (-1.32 mmol/L; 95% CI: -1.72, -0.93 mmol/L) was greater than that in the LCHP (P = 0.04) and ω-3 (P = 0.03) diet groups at 12 wk.

Conclusions

The LCHP+ω-3 diet provided greater effects on HbA1c and fasting glucose and faster effects on fasting glucose than both the LCHP and ω-3 diets, indicating the potential necessity of combining an LCHP diet with ω-3 PUFAs in T2D control. This trial was registered at chictr.org.cn/ as ChiCTR-TRC-14004704.

Association of decrease in carbohydrate intake with reduction in abdominal fat during 3-month moderate low-carbohydrate diet among non-obese Japanese patients with type 2 diabetes

OBJECTIVE

The effectiveness of a moderate low-carbohydrate diet (M-LCD) has been demonstrated in terms of glycemic control, body weight and serum lipid profiles. We investigated the effect of a 3-month M-LCD on visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), and examined an association between decrease in carbohydrate intake and reduction in abdominal fat among patients with Type 2 diabetes mellitus (T2DM).

METHODS

Seventy-six patients (45 men and 31 women; mean age ± SD: 59.5 ± 11.1 years) with T2DM were instructed to follow an M-LCD for 3 months. We assessed abdominal fat distribution using computed tomography and macronutrient intakes from 3-day dietary records at baseline and after 3 months.

RESULTS

The patients complied well with the M-LCD - %carbohydrate: %fat: %protein at baseline and after 3 months were 51:27:15 and 41:33:18 in men and 54:27:16 and 42:37:19 in women, respectively. VAT and SAT significantly decreased during the 3 months (P for time < 0.001 for both). Decrease in carbohydrate intake (g/day) and %carbohydrate were correlated with decrease (%) in VAT. The correlations were significant in men (Spearman correlation coefficient r = 0.469 for carbohydrate intake (g) and r = 0.402 for %carbohydrate) but not in women (r = 0.269 and 0.278, respectively). The correlations in men remained significant in multiple regression analysis adjusted for age and changes in energy intake.

CONCLUSIONS

In men, decrease in carbohydrate intake was significantly correlated with VAT loss during a 3-month M-LCD, independently of reduction in energy intake.

Three-graded stratification of carbohydrate restriction by level of baseline hemoglobin A1c for type 2 diabetes patients with a moderate low-carbohydrate diet

Background

A moderate low-carbohydrate diet has been receiving attention in the dietary management of type 2 diabetes (T2DM). A fundamental issue has still to be addressed; how much carbohydrate delta-reduction (Δcarbohydrate) from baseline would be necessary to achieve a certain decrease in hemoglobin A1c (HbA1c) levels.

Objective

We investigated the effects of three-graded stratification of carbohydrate restriction by patient baseline HbA1c levels on glycemic control and effects of Δcarbohydrate on decreases in HbA1c levels (ΔHbA1c) in each group.

Research design and methods

We treated 122 outpatients with T2DM by three-graded carbohydrate restriction according to baseline HbA1c levels (≤ 7.4% for Group 1, 7.5%-8.9% for Group 2 and ≥ 9.0% for Group 3) and assessed their HbA1c levels, doses of anti-diabetic drugs and macronutrient intakes over 6 months.

Results

At baseline, the mean HbA1c level and carbohydrate intake were 6.9 ± 0.4% and 252 ± 59 g/day for Group 1 (n = 55), 8.1 ± 0.4% and 282 ± 85 g/day for Group 2 (n = 41) and 10.6 ± 1.4% and 309 ± 88 g/day for Group 3 (n = 26). Following three-graded carbohydrate restriction for 6 months significantly decreased mean carbohydrate intake (g/day) and HbA1c levels for all patients, from 274 ± 78 to 168 ± 52 g and from 8.1 ± 1.6 to 7.1 ± 0.9% (n = 122, P < 0.001 for both) and anti-diabetic drugs could be tapered. ΔHbA1c and Δcarbohydrate were -0.4 ± 0.4% and -74 ± 69 g/day for Group 1, -0.6 ± 0.9% and -117 ± 78 g/day for Group 2 and -3.1 ± 1.4% and -156 ± 74 g/day for Group 3. Linear regression analysis showed that the greater the carbohydrate intake, the greater the HbA1c levels at baseline (P = 0.001). Also, the greater the reduction in carbohydrate intake (g/day), the greater the decrease in HbA1c levels (P < 0.001), but ΔHbA1c was not significantly influenced by changes in other macronutrient intakes (g/day).

Conclusions

Three-graded stratification of carbohydrate restriction according to baseline HbA1c levels may provide T2DM patients with optimal objectives for carbohydrate restriction and prevent restriction from being unnecessarily strict.